12 lighting

1200 Lighting

AbstractThis section provides technical and practical guidance for the design and selection of lighting systems. It defines and describes lighting, different types of light sources, factors to consider when selecting lamps and fixtures, and the design, layout, and maintenance of lighting systems. Design considerations including acceptable lighting levels for specific areas, economic factors, safety issues, and different methods for determining the number and layout (location) of fixtures are also discussed.

Contents Page

1210 Introduction 1200-3

1211 Section Guide

1220 Light Sources (Lamps) 1200-3

1221 Incandescent Lamps

1222 Fluorescent Lamps

1223 High Intensity Discharge Lamps

1224 Lamp Designations

1230 Fixture Selection 1200-8

1231 Area Classification

1232 Luminous Efficacy and Lumen Depreciation

1233 Color

1234 Cost

1235 Temperature

1236 Lamp Starting and Restarting

1237 Ballasts

1238 Fixture Materials

1239 Voltage Levels

1240 Lighting System Design 1200-21

Chevron Corporation 1200-1 September 1990

1200 Lighting Electrical Manual

1241 Distribution of Light

1242 Lighting Methods

1243 Illumination Level

1244 Lighting Level Reduction

1245 Emergency Lighting Systems

1246 Company Experience with Lighting Systems

1250 Lighting Calculations and Fixture Layout 1200-25

1251 Area Lighting

1252 Lumen Maintenance Factor (LMF)

1253 Watts-Per-Square Foot Method

1254 Iso-Footcandle Method

1255 Fixture Layout Using Iso-Footcandle Charts

1256 Fixture Layout Using Iso-Footcandle Tables

1260 Maintenance Considerations 1200-44

1270 Glossary of Terms 1200-45

1280 References 1200-46

1281 Model Specifications (MS)

1282 Standard Drawings

1283 Data Sheets (DS), Data Guides (DG), and Engineering Forms (EF)

1284 Other References

September 1990 1200-2 Chevron Corporation

Electrical Manual 1200 Lighting

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1210 IntroductionGood lighting systems provide two primary benefits in a facility: personnel safety and efficiency of operations. All decisions involving lighting system design and selection must take into consideration these two factors. This section contains infor-mation that provides guidance for selecting appropriate lighting systems. It also provides guidance for analyzing the efficiency of existing systems and for analyzing systems maintenance.

1211 Section GuideThe following guide directs the user to the appropriate sections.

If unfamiliar with different types of lamps, Section 1220, “Light Sources (Lampsshould be reviewed. General information is provided about incandescent, fluorecent, and different high intensity discharge (HID) lamps. HID lamp types includemercury vapor, metal halide, and high pressure sodium. This section is not inteto be used for the selection of lighting fixtures.

Section 1230, “Fixture Selection,” should be used as a guide in selecting the tyfixture. Factors discussed that influence fixture selection are: area classificationcolor rendition, luminous efficacy and lumen depreciation, cost, temperature, anlamp starting and restarting time. Three other factors should be considered whespecifying fixtures: ballast, fixture materials, and voltage level.

Section 1240, “Lighting System Design,” reviews the many considerations involin lighting design. These considerations include the type of light distribution, lighting methods, illumination levels, and emergency lighting systems. Many OPCOs have standardized particular fixtures. For these applications, the recommended illumination levels listed in API RP 540, Section 6, “Electrical Installatioin Petroleum Refineries,” and API RP 14F, “Design and Installation of ElectricalSystems for Offshore Production Platforms,” should be used to determine the nsary footcandle levels. Company experience is also outlined for many applicatio

Section 1250, “Lighting Calculations and Fixture Layout,” can be used to deter-mine the number of fixtures and their layout. Topics discussed are: area lightinglumen maintenance factor (LMF), and three computational methods, with two examples using the iso-footcandle method.

Section 1260, “Maintenance Considerations,” discusses relamping, cleaning fixtures, and cleaning lighted surfaces.

1220 Light Sources (Lamps)The primary purpose of an electrical light source is the conversion of electrical energy into visible light. The effectiveness with which a lamp accomplishes thisexpressed in terms of lumens emitted per watt of power consumed, or luminoucacy.



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For an idea of the relative luminous effectiveness of common light sources, consider that a 60-watt incandescent lamp (A-19 medium base soft-white) emits about 900 lumens in comparison to a 60-watt fluorescent lamp (cool white) which emits about 5600 lumens. This is roughly six times the lumens per watt of the incandescent lamp. In addition, the fluorescent lamp has a ten-times longer life than the incandes-cent lamp. To obtain the predicted long life of any lamp, it must be mounted according to the manufacturer’s instructions. Some lamps can only be mountedvertical position; others, only in a horizontal position. Some have a requirementthe base to be up, others for the base to be down. The most common types of lsources and their associated groups are shown below.

1221 Incandescent LampsThe filament lamp produces light by heating a wire filament to incandescence, which generates energy in the form of light and heat. The most common filamematerial is tungsten. All filament lamps emit a large quantity of heat with generaless than 5% light energy emitted. Both the life and light output of an incandesclamp are determined by the filament temperature. The higher the temperature fgiven lamp, the shorter the life. However, the larger the diameter of the filamenwire, the hotter the lamp can operate. This results in more light output, which inmeans higher efficacy. To illustrate this, consider that a 150-watt, 120-volt lampproduces approximately 34% more light than three 50-watt, 120-volt lamps. Incdescent lamps have a rated average life of about 1000 hours and radiate about20 lumens per watt. Vibration and shock should be eliminated as they can greareduce lamp life. Incandescent lamps are available with virtually unbreakable sand filaments where high vibration or rugged duty is required.

As a general rule, incandescent lamps should be operated at rated voltage. Ovvoltage operation produces higher wattage, higher efficacy, and higher light outbut results in a shorter life. Undervoltage, while increasing lamp life, causes a reduction in wattage, efficacy, and light output. A voltage as little as 5% below normal results in a loss of light of more than 16%, with a savings in wattage of 8%. Since the lamp cost is almost always small compared with the cost of the pto operate the lamp, the increased lamp life which accompanies reduced voltagdoes not compensate for the loss in light output. Maintaining the proper voltagean important factor in obtaining good performance from lamps and lighting instations.

Type Group

Incandescent Filament

Fluorescent Fluorescent

Mercury Vapor High Intensity Discharge

Metal Halide High Intensity Discharge

High Pressure Sodium (HPS)

High Intensity Discharge



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1222 Fluorescent LampsThe fluorescent lamp contains mercury vapor at low pressure with a small amount of inert gas for starting. When voltage is applied, an “arc” discharge is producedcurrent flowing through the mercury vapor. The discharge generates ultraviolet ation which excites the fluorescent powders on the inner wall of the lamp, whichturn emit light.

Like most gas discharge lamps, fluorescent lamps must be operated in series wballast. The ballast produces the required voltage to start and operate the lampthe required current to produce the desired light output.

Fluorescent lamps have a rated average life of about 20,000 hours when operafor a minimum of 3 hours per start. The lamps radiate about 74 to 84 lumens pewatt.

The average lamp life for fluorescent lamps is affected by the number of on-off operations. A rule-of-thumb is that each lamp start reduces the average lamp li3 hours. This might imply that fluorescent lamps should be operated continuousduring the day to save lamp life rather than being turned off when not in use to energy. However, the light should be turned off to save energy because approxmately 80% of the life-cycle cost of a fluorescent lamp is for electrical energy. Tlife of F40 and F30 lamps, operating on rapid start ballasts when burned 3 or mhours per start, is not appreciably affected by the number of starts. All burned-olamps should be removed promptly to prevent the auxiliary equipment from oveheating. Depreciation in light output of the fluorescent lamp is due chiefly to a gradual deterioration of the phosphor powders and a blackening of the inside otube. In the last hours of lamp life, a dense deposit develops at the end of the lawhere the electrode is deactivated. This effect is especially marked if the lamp allowed to flash on and off before it is replaced.

Low voltage, as well as high voltage, reduces efficiency and shortens fluorescelamp life. This is in contrast with filament lamps, where low voltage reduces efficiency but prolongs life. Low voltage and low ambient temperatures may also cstarting difficulties with fluorescent luminaires.

A large voltage dip or reduction in line voltage affects the stability of the arc. Threaction to a voltage dip depends on the lamp type and ballast characteristics. 40-watt, T-12 lamps, the line voltage can drop to the values illustrated in the tabbelow before the lamps will extinguish:

Type Percent of Normal Voltage

Preheat 75

Rapid-start series-sequence 80

Instant-start lead-lag 60

Instant-start series-sequence 50



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1223 High Intensity Discharge LampsHigh intensity discharge (HID) lamps that are commonly used include mercury vapor, metal halide, and high pressure sodium. The light producing element of these lamps is a stabilized arc discharge contained within an arc tube. Light is produced by the passage of an electric current through a vapor or gas rather than through a tungsten wire. The applied voltage ionizes the gas and permits current to flow between two electrodes located at opposite ends of the lamp. The electrons which comprise the current stream, or “arc discharge,” are accelerated to tremendousspeeds. When they collide with the atoms of the gas or vapor, they temporarily the atomic structure, and light is produced from the energy generated as the atoreturn to their normal state.

Low pressure sodium lamps are not recommended because of very poor color tion and high operating costs.

Mercury Vapor LampsMost mercury vapor (MV) lamps are constructed with two envelopes, an inner envelope (arc tube) which contains the arc, and an outer envelope which: (a) shthe arc tube from outside drafts and resulting changes in temperature; (b) usuacontains an inert gas which prevents oxidation of internal parts; (c) provides aninner surface for a coating of phosphors; and (d) acts as a filter to remove certawavelengths of arc radiation.

A significant part of the energy radiated by the mercury arc is in the ultraviolet region. Through the use of phosphor coatings on the inside surface of the outerenvelope, some of this ultraviolet energy is converted to visible light by the sammechanism employed in fluorescent lamps.

Mercury lamps used in open-type fixtures can cause serious skin burn and eyeinflammation from shortwave ultraviolet radiation if the outer envelope of the lamis broken or punctured and the arc tube continues to operate. For this reason, nenclosed fixtures should be specified with self-extinguishing lamps that will automatically extinguish if the outer envelope is broken or punctured. Self-extin-guishing lamps cost about twice as much as standard lamps.

Metal Halide LampsMetal halide (MH) lamps are very similar in construction to mercury lamps. Themajor difference is that the metal halide arc tube contains various metal halidesaddition to mercury and argon.

Almost all varieties of available “white-light” metal halide lamps produce color rendering which is equal or superior to the presently available phosphor coatedmercury lamps. Metal halide lamps are also available with phosphors applied toouter envelopes to further modify the color.

Most metal halide lamps require a higher open-circuit voltage to start than corresponding wattage mercury lamps. Therefore, they require specifically designedballasts.



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Metal halide lamps are constructed of a glass envelope with an internal arc tube made of quartz. These arc tubes operate under high pressure (6 to 7 atmospheres) at a very high temperature (up to 900°C). The arc tube may unexpectedly rupture due to internal causes or external factors, but most commonly ruptures when the lamp is operated beyond its rated life. If the arc tube ruptures, the glass envelope surrounding the arc tube can break, allowing particles of extremely hot quartz from the arc tube and glass fragments from the glass envelope to be discharged into the fixture enclosure and surrounding area. This circumstance creates a risk of personal injury or fire. Metal halide lamps should always be used in enclosed fixtures with lens/diffuser material which is able to contain fragments of hot quartz or glass.

To reduce the potential hazard of ruptured arc tubes, use metal halide lamp manu-facturers with proven lamps. Additional precautions to use to reduce the likelihood of arc tube rupture are:

1. Turn continuously operating lamps off once a month for at least 15 minutes. Lights which are close to the end of their design life likely will not restart. This procedure will reduce the chance of arc tube rupture caused by continuously operating lamps burning beyond the end of rated life.

2. Relamp fixtures at or before the end of their rated life. Allowing lamps to operate beyond their design life increases the possibility of arc tube rupture.

Like mercury vapor lamps, metal halide lamps can cause serious skin burn and eye inflammation from shortwave ultraviolet radiation if the outer envelope of the lamp is broken or punctured and the arc tube continues to operate. When using open-type fixtures, self-extinguishing lamps that automatically extinguish when the outer envelope is broken or punctured should be specified.

High Pressure Sodium LampsIn a high pressure sodium (HPS) lamp, light is produced by electric current passing through sodium vapor. The arc tube contains xenon as a starting gas. Special ballasts are required which incorporate starting voltages in the range of 2250 to 4000 volts to strike the arc. These high strike voltages can result in high temperatures which could possibly create problems in classified areas. HPS lamps do not incorporate a starting electrode or heater coil as do mercury vapor and metal halide lamps.

Arc tube rupture is not a problem with high pressure sodium lamps since the arc tube is made of ceramic material. Shortwave radiation is also not a concern with high pressure sodium lamps.

1224 Lamp DesignationsLamp designations follow a system authorized by the American National Standards Institute (ANSI). All designations begin with a letter that identifies the type of HID lamp: “H” for mercury, “M” for metal halide, and “S” for high pressure sodium. This letter designation is followed by an ANSI assigned number which identifieselectrical characteristics of the lamp and, consequently, the ballast. After the number, two arbitrary letters identify the bulb size, shape, and finish, but do not



identify the color. Additional letters are used by individual manufacturers for special designations.

1230 Fixture SelectionA thorough understanding of the purpose for a lighting system must be established before the various selection factors can be evaluated. Figure 1200-1 lists fixture types and typical applications in order of preference for locations that require maximum light output at the lowest possible operating cost. On offshore platforms where power is generated and the physical layout prevents full use of light output, mercury vapor fixtures are often preferred. They give better color rendition and have lower installed costs in situations where some of the light is lost due to shadows. When several possible fixture types have been chosen, a review of the features of each one can be made to complete the selection process.

Fig. 1200-1 Light Fixture Selection (1 of 2)

Light Fixture Type

Application Incandescent Fluorescent MV MH HPS

Outdoor:

Entrance Illumination 4 2 3 1

Wall Illumination 2 1

Ladder Illumination 3 2 1

Emergency Lights 2 4 3 1 (with instant restrike)

Area Floodlighting 3 2 1

Walkways 4 3 2 1

Roadways 1

Corridors 2 4 3 1

Canopy Lighting 1

Heliports 2 1

Indoor:

Small Store Rooms 1 2

Exit Lights 1

Stairways 2 1

Bulkheads 1

Emergency Lights 2 1

Offices 1

Control Rooms 1

Living Areas 2 1



1231 Area ClassificationArea classification must be determined before selecting lighting fixtures. Refer to Section 300 of this manual for guidance in determining area classification and Section 340 for specific lighting fixture considerations. Refer to the area classifica-tion drawing of the facility in which the lighting fixture is to be installed to identify the proper area classification.

The fixture temperature must not exceed the ignition temperature of flammable gases or vapors present. See Figure 1200-2 for temperature identification numbers and T-Ratings for typical fixtures.

1232 Luminous Efficacy and Lumen DepreciationOne of the two primary factors used in fixture selection is the luminous efficacy (lumens per watt) of the light source. The other primary factor is the initial cost of the fixture. For fixtures that have a long life, the luminous efficacy, which relates directly to the operating cost of the lamp, usually will govern the selection process. These factors usually do not govern fixture selection when shadows prevent full use of light output or when power is generated at very low cost (e.g., on offshore plat-forms).

Lumen depreciation is a reduction in normal light output that is unique to each type of lamp. It is an important factor during the design and fixture layout process. For example, the light output of a mercury vapor lamp at the end of rated life will only be about 50% of its original light output. By comparison, the light output of high pressure sodium and fluorescent lamps at the end of rated life will be about 80% of their original light output.

Luminous Efficacy and Lumen Depreciation SummaryFigure 1200-3 and Figure 1200-4 summarize the luminous efficacy and lumen depreciation for different light sources.

Corridors 2 1

Switchgear Buildings 1

High Bay Area Lighting 3 2 1

Warehouses 3 2 1

Notes: 1. Number indicates order of preference, 1 being the most preferred.2. See Section 1230, “Fixture Selection,” for discussion of limited-light applications and low-cost power usage.

Fig. 1200-1 Light Fixture Selection (2 of 2)

Light Fixture Type

Application Incandescent Fluorescent MV MH HPS



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1233 ColorIn some applications, color rendition is the dominant factor in fixture selection. For example, metal halide fixtures are typically used in the canopy area of service stations because of the pleasing visual effect of the light. Metal halide lamps use more energy per lumen output and have a shorter life than high pressure sodium lamps, but the visual attractiveness obtained by using metal halide lamps outweighs their added operating cost.

Mixing high pressure sodium with metal halide or mercury vapor is not recom-mended because of the contrasting colors. Mixing luminaires becomes a problem when color rendition is important—for example, for distinguishing colors, for reading, and when performing precision, task-oriented activities. Mixing luminaalso presents a maintenance problem during relamping, when time is lost locatthe correct lamps.

Incandescent Filament LampsIncandescent light closely resembles natural sunlight, with good color rendition

Fluorescent LampsThe color produced by a fluorescent lamp depends upon the blend of phosphorused to coat the wall of the tube. There are different “white” and color spectrum

Fig. 1200-2 Technical Data: Temperature Identification Numbers of Typical Fixtures (Courtesy of Appleton Electric Company)



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fluorescent lamps available with their own particular coloration. “White” lamps have good color rendering properties.

High Intensity Discharge (HID) LampsA discussion of the color aspects of HID lamps follows.

Mercury Vapor (MV) Lamps. The color spectrum of “clear” mercury lamps is deficient in red and has a preponderance of blue and green. This results in mardistortion of object colors, and makes mercury vapor lamps undesirable when tappearance of colors is important. This deficiency can be overcome by using “deluxe white” (color-corrected) lamps in which fluorescent phosphor coatings aadded to the lamps to improve color rendering. MV lamps have poorer color rention than MH lamps, but better color rendition than HPS lamps. MV lamps are bused for general lighting (street, industrial, and flood-lighting) where color rendering is not extremely important or where the full output of an HPS lamp wnot be utilized because of shadowing.

Metal Halide (MH) Lamps. The color spectrum of “clear” metal halide lamps is equal to or superior to phosphor-coated mercury vapor lamps. Phosphor coatincan be added for better color. MH lamps are best used where color rendering isimportant and in general lighting where only a few fixtures are required.

High Pressure Sodium (HPS). The color spectrum of high pressure sodium lampconsists of white light with a yellow-orange tone. HPS lamps are best used for

Fig. 1200-3 Efficacies for Various Light Sources (from The IESNA Lighting Handbook Reference and Application, Ninth Edition. Courtesy of IESNA)



Fig. 1200-4 Lumen Depreciation Factor (LDF) (from “Philips Lighting Guide to High Intensity Discharge Lamps" Printed 8/91, publication # P-2685, pages 7, 12, and 16. Courtesy of the Philips Lighting Company.)



general lighting of large areas where good color rendition is a secondary consider-ation.

1234 CostHigh pressure sodium lamps are usually the best economic choice for lighting large areas, primarily because of their low operating cost and long life. Such areas include: floodlighting, general area lighting, road way lighting, and warehouse lighting. Metal halide is the second most cost effective choice for outdoor lighting, followed by fluorescent. Mercury vapor fixtures should not be used in new installa-tions due to poor luminous efficacy and high lumen depreciation (which results in high operating costs) except for specific locations as discussed below. In fact, it may be cost effective to retrofit existing mercury vapor installations with high pressure sodium lamps.

At locations where power is purchased or generated at low cost and physical layout prevents full use of light output, metal halide or mercury vapor fixtures may be more cost effective. An economic evaluation should be performed.

Fluorescent lamps are often the preferred choice for enclosed areas, especially for control rooms, office buildings, and laboratories with low ceiling clearance. High pressure sodium lamps are often preferred for warehouses and indoor process areas. Incandescent lamps should be used sparingly, and only for specialty applications (e.g., emergency lighting) or where lighting is used infrequently and the initial fixture cost is low compared to alternative lighting fixtures.

Fluorescent LampsFigure 1200-5 shows a cost analysis for energy-saving versus standard efficiency fluorescent lamps. This analysis indicates that energy-saving lamps should be speci-fied even when the time value of money is as high as 20%. Energy-saving lamps are more cost effective because the average lamp life is long (almost 7 years) and energy represents more than 80% of the life cycle cost (LCC) of operating lamps.

High Intensity Discharge LampsFigure 1200-6 shows a cost analysis to light a 50,000 square foot area to an illumi-nation level of 5 footcandles. The analysis is based on using Class I, Division 2 (UL-844) fixtures, with an energy cost of $0.08/KWH, and 4000 burning hours per year. For different costs of power and labor, ratio actual costs to the costs used in this example (e.g., $0.04/KWH/$0.08/KWH=$4,864.00 annual operating cost). The undiscounted life cycle cost (LCC) of using HPS lamps in this example is approxi-mately $300,000. By comparison, the undiscounted LCC of MV lamps is more than $720,000. This cost does not consider the added cost of source equipment (trans-formers and panelboards) for the MV lamp option (with a connected load of 82 KW versus 30 KW for the HPS option). In addition, more conduit, wire, and lamp stan-chions are required for the MV lamp option. The metal halide option is also a better choice economically than mercury vapor.

Figure 1200-7 illustrates another example in which one HPS, MV, or MH fixture provides a maintained minimum illumination of 5 footcandles. In this example, the



MV option has the lowest initial cost and the lowest LCC even when the time value of money is over 20%.

Figure 1200-8 demonstrates a retrofit example in which MV lamps are presently in use. An initial investment of approximately $96,000 will be required to retrofit to HPS or $104,000 to retrofit to MH. Based on a 10-year LCC, the option to retrofit with HPS yields a savings even when the time value of money is as high as 12%. Retrofitting with MH is not a cost effective option. This also is true when using a 20-year LCC. However, when the cost of energy is below $0.05/KWH, it is not cost effective to change out the MV lights. An economic analysis should be performed for each possible situation.

Fig. 1200-5 Cost Analysis: Comparison of Fluorescent Lamps—Energy Savers vs. Standard Lamps

F40CW Standard F40 Energy Saver

Number of Luminaires Required 1.00 1.00

Initial Lumens Per Lamp 3,150.00 2,775.00

Estimated Lamp Life (Hrs) 20,000 20,000

Average Lamp Replacements/yr 0.15 0.15

Lamp Net Cost After Discount ($/lamp) 1.24 1.72

Lamp Input (watts/lamp) 40.00 34.00

Total Connect Load (W) 40 30

Relamp Labor/lamp @$50/hr 10.00 10.00

Annual Operating Cost ($)

Relamp Cost: Lamps 0.19 0.26

Relamp Cost: Labor 1.50 1.50

Energy Cost 9.60 8.16

Total Annual Operating Cost 11.29 9.92

20 Year Operating Cost ($)

Relamp Cost: Lamps 3.72 5.16

Relamp Cost: Labor 30.00 30.00

Energy Cost 192.00 163.20

Total 20 Year Operating Cost 225.72 198.36

20 Year Life Cycle Cost ($–discounted)

8% Discount Rate 110.81 97.38






Fig. 1200-6 Cost Analysis: High Intensity Discharge Fixtures

High Intensity Discharge Fixtures

Basis:

50,000 Sq Ft Area; Illuminated to 5 fc4,000 Burning Hrs Per Yr; Energy Cost = $0.08/KwhArea Class: Class I, Division 2, Group D

150 W HPS 175 W MV 175 W MH

Number of Luminaires Required 160 357 200

Initial Lumens Per Lamp 16,000 8600 14,000

Lumen Maintenance Factor 0.60 0.50 0.55

Total Lumens 1,536,000 1,535,000 1,540,000

Estimated Lamp Life (hrs) 24,000 24,000 10,000

Avgerage Lamp Replacements/yr 27 60 80

Lamp Net Cost ($) 27 16 29

Luminaire Input (watts/fixture) 190 230 230

Total Connected Load (kw) 30.40 82.11 46.00

Fixture Cost ($) 350 310 300

Installation Labor/Fixture @ $50/hr 150 150 150

Relamp Labor/Lamp @ $50/hr 10 10 10

Initial Installation Cost ($)

Fixture Cost 56,000 110,670 60,000

Labor Cost 24,000 53,550 30,000

Total Initial Cost 80,000 164,220 90,000


Relamp Cost: Lamps 729 952 2,320

Relamp Cost: Labor 270 595 800

Energy Cost 9,728 26,275 14,720

Total Annual Operating Cost 10,729 27,822 17,840


Relamp Cost: Lamps 14,580 19,040 46,400

Relamp Cost: Labor 5,400 11,900 16,000

Energy Cost 194,560 525,504 294,400

Total 20 Year Operating Cost 214,540 556,444 356,800

20 Year Life Cycle Cost ($–undiscounted) 294,540 720,664 446,800


8% Discount Rate 225,615 542,332 332,451

10% Discount Rate 202,896 483,338 294,623

12% Discount Rate 185,198 437,382 265,155

20% Discount Rate 143,525 329,173 195,770



Fig. 1200-7 Cost Analysis: High Intensity Discharge Fixtures

High Intensity Discharge Fixtures

Basis:

Equal Number of Fixtures; Illumination Minimum to 5 fc;4,000 Burning Hrs Per Yr; Energy Cost = $0.08/kwh;Area Class: Class I, Division 2, Group D

70 W HPS 100 W MV 175 W MH

Number of Luminaires Required 1 1 1

Initial Lumens Per Lamp 5800 4200 14,000

Lumen Maintenance Factor 0.60 0.50 0.55

Total Lumens 3,480 2,100 7,760

Estimated Lamp Life (hours) 24,000 24,000 10,000

Avgerage Lamp Replacements/yr 0.17 0.17 0.40

Lamp Net Cost ($) 29 19 29

Luminaire Input (watts/fixture) 102 132 230

Total Connected Load (kw) 0.10 0.13 0.23

Fixture Cost ($) 325 215 300

Installation Labor/Fixture @ $50/hr 150 150 150

Relamp Labor/Lamp @ $50/hr 10 10 10

Initial Installation Cost ($)

Fixture Cost 325 215 300

Labor Cost 150 150 150

Total Initial Cost 475 365 450


Relamp Cost: Lamps 4.80 3.20 11.60

Relamp Cost: Labor 1.70 1.70 4.00

Energy Cost 32.60 42.20 73.60

Total Annual Operating Cost 39.10 47.10 89.20


Relamp Cost: Lamps 97 63 232

Relamp Cost: Labor 33 33 80

Energy Cost 652 844 1,472

Total 20 Year Operating Cost 782 941 1,784

20 Year Life Cycle Cost ($–undiscounted) 1,257 1,306 2,234


8% Discount Rate 1,006 1,004 1,662

10% Discount Rate 923 904 1,473

12% Discount Rate 859 827 1,325

20% Discount Rate 707 644 978



Fig. 1200-8 Fixture Retrofit Cost Analysis

Replace Existing Mercury Vapor (MV) FixturesBasis:

50,000 Sq Ft Area; Illuminated to 5 fc4,000 Burning Hrs Per Yr; Energy Cost = $0.08/kwhArea Class: Class I, Division 2, Group D

150 W HPS 175 W MV 175 W MHNumber of Luminaires Required 160 357 200Initial Lumens Per Lamp 16,000 8,600 14,000Lumen Maintenance Factor 0.60 0.50 0.55Total Lumens 1,536,000 1,535,000 1,540,000Estimated Lamp Life 24,000 24,000 10,000Avgerage Lamp Replacements/yr 27 60 80Lamp Net Cost ($) 27 16 29Luminaire Input (watts/fixture) 190 230 230Total Connected Load (kw) 30.40 82.11 46.00Fixture Cost ($) 350 0 300Installation Labor/Fixture @ $50/hr 150 0 150Relamp Labor/Lamp @ $50/hr 10 10 10Initial Installation Cost ($)Fixture Cost 56,000 0 60,000Engineering 6,000 0 6,000Installation Labor Cost 24,000 0 30,000Remove MV Fixtures ($50/fixture) 9,850 0 7,850Total Initial Cost 95,850 0 103,850Annual Operating Cost ($)Relamp Cost: Lamps 729 952 2,320Relamp Cost: Labor 270 595 800Energy Cost 9,728 26,275 14,720Total Annual Operating Cost 10,727 27,822 17,84010 Year Operating Cost ($)Relamp Cost: Lamps 7,290 9,520 23,200Relamp Cost: Labor 2,700 5,950 8,000Energy Cost 97,280 262,752 147,200Total 10 Year Operating Cost 107,270 278,222 178,40010 Year Life Cycle Cost ($–undiscounted) 203,120 278,222 282,25010 Year Life Cycle Cost ($–discounted)8% Discount Rate 167,746 186,689 223,55710% Discount Rate 161,686 170,955 213,46912% Discount Rate 156,390 157,201 204,64920 Year Life Cycle Cost ($–discounted)8% Discount Rate 201,048 273,162 279,00510% Discount Rate 187,070 236,866 255,73112% Discount Rate 175,882 207,816 237,10414% Discount Rate 166,814 184,270 222,006



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1235 TemperatureTemperature can affect the installation and operation of light sources in many ways. Ambient temperatures can affect the lumen output of some fixtures. Self-generated heat in excess of that which is designed to be dissipated by the fixture can damage the ballast, lamp, base, and fixture. Ballast life is very sensitive to high ambient temperatures. For high ambient temperature areas, it may be more cost effective to use fixtures with remote-mounted ballasts, even though the initial costs for fixtures with integral ballasts may be lower. Fixtures must be mounted according to manu-facturers recommendations to correctly dissipate heat.

Incandescent Filament LampsOperation of lamps under conditions which cause excessive bulb and base tempera-tures may result in softening of the base cement and loosening of the base. In extreme cases, the fixture and adjacent wiring can be damaged. Care should be taken to ensure that the correct wattage lamps are installed in fixtures. Most fixtures are designed to dissipate a specific quantity of heat generated by the lamps. Over-voltage conditions or the use of lamps of higher wattage than the manufacturerrating can cause slight or severe damage. The use of incorrect wattage lamps also affect light distribution by fixtures since the focal point will not be correct foreflectors.

Fluorescent LampsTemperature is an important factor in the performance of fluorescent lamps. Thtemperature of the bulb wall has a substantial effect on the amount of ultraviolelight generated by the arc; therefore, light output is significantly affected by the temperature and movement of the surrounding air. For maximum efficiency, bulwall temperatures should be within a range of 100° to 120°F. Light output decreasesabout 1 percent for each 1-degree drop in bulb temperature below 100°F, and decreases a like amount for each 2-degree rise between 120° to 200°F.

When fluorescent lamps with “P” ballasts are installed, fixtures must be able to dissipate the heat which is generated. Insulation around the fixture, or a fixture installed in a high ambient temperature area, can cause the ballast protection toin and out, turning the lamp off and on unpredictably.

Low temperatures may also cause starting difficulty. This normally is not a probwith indoor applications, but can become a significant problem outdoors.

For outdoor applications, fluorescent lamps designed for outdoor use are recommended because of their high lumen output. In order to maintain high output in climates, the lamps must be enclosed. Enclosing the lamps shifts the peak outpa lower ambient temperature. When using lamps in cold weather without a surrounding enclosure, best results will be obtained from T10J lamps specificaldesigned for use in low air temperatures.

High Intensity Discharge LampsThe lumen output of the enclosed arc-tube type lamp is not significantly affecteambient temperature. However, to insure immediate starting at low temperature



many HID lamps require a ballast which has a higher open-circuit voltage than that of a standard ballast designed for a temperature-controlled environment.

Because HID lamps have a long life, operating temperatures are particularly impor-tant. The effect of heat is partly a function of time, and the longer the life of the lamp, the greater the possibility of damage from high temperature. Excessive bulb and base temperatures may cause the following conditions: lamp failure, unsatisfac-tory performance due to softening of the glass, damage to the arc tube from mois-ture being driven out of the outer envelope, softening of the basing cement or solder, or corrosion of the base, socket, or lead-in wires. The use of any reflecting equip-ment that might concentrate heat and light rays on either the inner arc tube or the outer envelope should be avoided.

1236 Lamp Starting and RestartingLamp starting and restarting can be an important consideration if there is a signifi-cant time delay before light output can be achieved. This factor can be important in remote locations, or in an industrial setting where an unsafe condition may exist after a power dip if light is not restored immediately. Of all luminaires, metal halide lamps take the longest time to restart and reach full power output after a power failure.

Incandescent LampsIncandescent lamps achieve immediate light output upon starting and restarting.

Fluorescent LampsFluorescent lamps should be equipped with rapid-start ballasts which provide imme-diate starting and restarting characteristics.

High Intensity Discharge (HID) LampsAll HID lamps need time to reach full output and stable color. If the arc is extin-guished after this warm-up, the lamp will not relight until it is cooled sufficiently to lower the vapor pressure of the gases to a point where the arc will restrike with the available voltage.

Some ballasts can be equipped with a restart circuit that will provide sufficient starting voltage to overcome the higher vapor pressure of the gases. Ballasts equipped with restart circuits provide full light output immediately upon restoration of power. Battery-powered emergency lighting systems may be required for outages which are longer than momentary outages.

Epoxy encapsulated ballasts should be considered for high humidity areas and corrosive environments. The epoxy protects the ballast from possible contaminants.

Mercury Vapor (MV) LampsThe time from initial starting to full light output at ordinary room temperature varies from 5 to 7 minutes. Restrike time (including cooling time until the lamp will restart) varies between 3 and 6 minutes.



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Mercury vapor lights with an auxiliary quartz lamp are available. The incandescent quartz lamp lights immediately when the circuit is restored. When the MV lamp attains 75% of its rated output, a current sensing relay turns the quartz lamp off. Quartz lamps operate at temperatures which are above those allowed for Class I, Division 1 or 2 areas.

Metal Halide (MH) LampsThe warm-up time for MH lamps is slightly less than that of MV lamps, varying between 2 and 5 minutes. Since MH arc tubes operate at higher temperatures than MV lamps, the time to cool and lower the vapor pressure of the metal halide lamp is longer, varying between 10 and 20 minutes.

High Pressure Sodium (HPS) LampsThe lamp warm-up time for HPS lamps is between 3 and 4 minutes, and full light output is reached in approximately 10 minutes. Because the operating pressure of a high pressure sodium lamp is lower than that of a mercury lamp, the restrike time is shorter, between 0.5 and 1 minute. Ninety percent of full light output is reached in 3 to 4 minutes. HPS lamps can be equipped with a special feature called “InstantRestrike” for convenience (or for use as emergency lighting) when uninterrupteillumination is required. With this feature, some light is available immediately. Light output reaches 30% of full output after 1/2 minute. Full light output is achieved in about 3 minutes.

Lamp Start and Restrike SummaryFigure 1200-9 summarizes the lamp starting and restrike times for the various Hlight sources.

1237 Ballasts

Fluorescent LampsThe components of a typical rapid start ballast consist of a transformer-type corand coil, power capacitor, thermal protective device, and a potting compound (sas asphalt) containing a filler (such as silica). The average ballast life at a 50% cycle and proper operating temperature is about 12 years.

In the United States and Canada, it is mandatory that all fluorescent lamp ballasthermally protected internally. The thermally protected Underwriters’ Laboratoryapproved ballast is marked or labeled as “Class P.” Ballasts should also be liste

Fig. 1200-9 Lamp Start and Restrike Time (in Minutes)

Type of Lamp

MV MH HPS Incandescent Fluorescent

Start Time 5-7 2-5 3-4 immediate immediate

Restrike Time 3-6 10-20 0.5-1(1) immediate immediate

(1) Also available with instant restrike.



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the Certified Ballast Manufacturers Association (CBM). All CBM listed ballasts are also UL listed. CBM publishes sound ratings for ballasts.

High Intensity DischargeThe Constant Wattage Autotransformer “CWA” lead circuit ballast is the preferrechoice for most HID installations. It consists of a high reactance autotransformewith a capacitor in series with the lamp. The capacitor allows the lamp to operawith better wattage stability if branch circuit voltage fluctuates. Other advantagethe CWA ballast are a high power factor, low-line extinguishing voltage, and lowline starting currents. Fixtures with ballasts other than CWA will require approximately 60% more starting current than operating current. The CWA features allmaximum loading on branch circuits and provide more cost-effective HID lightinsystems.

1238 Fixture MaterialsFixture material may be an important consideration in the selection of lighting fixtures, especially in marine environments. Underwriters’ Laboratories StandarUL-595 covers marine-type electric light fixtures. Outdoor fixtures for use on shboard or offshore platforms should be UL-595 listed.

1239 Voltage LevelsThe voltage level of the electrical supply is discussed in Section 100, “System Design.” Incandescent and fluorescent fixtures normally are supplied with 120 volts. HID fixtures can be supplied at 120, 208, 240, 277, or 480 volts. Many lotions have standardized a particular voltage level. This practice should be investigated before selecting fixtures. Many locations prefer 120 volts for all fixtures for safety considerations, easier phase balancing, and reduced inventorfixtures and ballasts.

1240 Lighting System DesignBefore the system design process can begin, the following design parameters mbe determined: area classification, fixture selection, and voltage level. In additiothe following project design tasks must be completed: facility layout, mechanicaequipment plans, structural plans, and emergency escape routes.

The design of any lighting installation involves the consideration of many vari-ables. These variables include: (1) lighting for detailed work, (2) flood lighting, (task-oriented lighting, and (4) emergency lighting. The lighting system should bdesigned to provide slightly more than the initial desired light to allow for lamp deterioration and dirt accumulation on the fixture lens (i.e., maintenance factor luminaire depreciation factor). The lighting system should also be designed to provide the desired quantity of light at the particular location and in the proper visual plane. The amount of glare produced, the ease of installation and maintenance, and environmental suitability (e.g., indoors, outdoors, and hazardous lotions) should all be considered during the design phase.



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1241 Distribution of LightThe distribution of light is divided into five classes: direct, semi-direct, general-diffuse (or direct-indirect), semi-indirect, and indirect.

• Direct lighting provides 90 to 100% of its light downward, and while it often most efficient, it usually results in glare.

• Semi-direct lighting provides 60 to 90% of its light downward, with a generadecrease in glare and increase in seeing comfort.

• General-diffuse (direct-indirect) lighting systems provide approximately equal components of up-light and down-light. This system emits very little brightness in the direct-glare zone. The efficiency of the system depends laon the reflectances of all the room surfaces. This system is widely used in ratories and offices.

• Semi-indirect lighting provides 60 to 90% up-light and depends on light beinreflected from the ceiling and walls. This type of lighting system is used whreflected glare from room surfaces must be minimized.

• Indirect lighting systems provide 90 to 100% up-light and produce the mostcomfortable light. However, they have the lowest utilization of the five classand often are difficult to maintain. Indirect lighting is preferred for control rooms with CRT monitors.

1242 Lighting MethodsTo provide the necessary quantity and quality of light for lighting system applications, three types of lighting are used.

• General lighting should provide overall, uniform lighting with special atten-tion focused on the areas along walls. The lighting level at the wall should bcomparable to that at the center of the room. An example of this is in the buareas of living quarters.

• Localized general lighting is used in areas where higher illumination levels are required. This often can be obtained by increasing the output of the genlighting system in the particular area.

• Supplementary luminaires are used to provide higher levels of illumination ismall or restricted areas.

The illumination of vertical surfaces often requires special considerations to prouniformity and, in those cases where the vertical surface is behind a transparencover, to prevent reflected glare. Where vertical surfaces are adjacent to sourcehigh luminance, acceptable brightness ratios should be maintained to help avoeye-strain caused by a large difference in brightness between the task area andbackground.



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1243 Illumination LevelCompany experience has shown that the lighting levels listed in API RP 540, Section 6, “Electrical Installations in Petroleum Refineries,” and API RP 14F, “Design and Installation of Electrical Systems for Offshore Production Platformsare adequate and are recommended for Company installations.

1244 Lighting Level ReductionIn the interest of energy conservation, lighting levels which exceed the standardrecommendation should be reduced. Levels listed for office areas are based on1974 guidelines of the Federal Energy Administration. Persons with uncorrectavisual difficulties and those performing difficult visual tasks may require supple-mental lighting. When supplemental lighting is provided in the form of desk or fllamps, the lamps should be selected and placed so that minimum glare is intro

Lighting level reductions often are made by removing fluorescent lamps from fixtures. Even if all lamps are removed from a fluorescent fixture, energy is still consumed by the ballasts. Certain considerations and precautions must be mawhen removing fluorescent lamps:

1. With the exception of Slim-Line (Instant-Start) lamps, all lamps connected tgiven ballast should be removed. Removing only a portion of the lamps froballast can cause damage to the ballast from overheating. Most four-lamp fixtures operate from two ballasts, with two lamps on each ballast. Removinonly one or three lamps from this type of fixture is not a safe practice. Eithefour lamps should be removed or two lamps operating from the same ballashould be removed. UL rating and manufacturer’s warranties are normally invalidated if the above steps are not followed. There is one exception to thrule: any number of lamps can be removed from a Slim-Line (Instant-Start)fixture providing the fixture is equipped with circuit-interrupting lampholdersas required by UL. If maintenance personnel are uncertain about the lampholder type, technical assistance should be obtained before lamps areremoved.

2. When lamps are removed from a fixture, a potential voltage remains at thesockets which could be dangerous. A suitable protective cap should be usethe sockets should be taped with high temperature tape. All maintenance personnel who are likely to be working on or cleaning these fixtures shouldmade aware of this potentially dangerous condition.

3. As a general rule, the power factor in a given installation will not drop below90% provided that no more than one-half of the lamps are removed. Disconnecting additional lamps lowers the power factor further, resulting in highercurrents and possible utility charges for excessive use of reactive power.

4. A ballast will continue to draw current after all lamps are removed (except ffixtures with circuit-interrupting lampholders), resulting in wasted energy anpossible overheating of the ballast. For example, measurements taken on alamp, 40 watts-per-lamp, Rapid-Start fixture show that each ballast uses 10



watts of power with all lamps removed. Therefore, if practical, and especially if the reduction in lighting level is to be permanent, the ballast should be discon-nected from the power source.

1245 Emergency Lighting SystemsEmergency lighting is used during power failures and provides illumination by silhouetting objects. It should be provided in control rooms, at critical instrument locations, in large electrical substations, in mechanics shops, and in laboratories. Emergency systems are used to evacuate personnel, to provide light to shut down controls and equipment, and to maintain a level of illumination adequate for safety and security. It may also be required to illuminate equipment for plant startup following a power outage. Local, city, state, and federal codes may require emer-gency lighting for special areas where personnel work. Applicable codes should be reviewed carefully.

The power source for emergency lighting systems should be separate from the normal electrical source. If the same power source is used for both normal and emergency lighting, a power outage would render the emergency lighting useless. Emergency lighting power sources include engine generator sets, UPS, and batteries. If normal power is lost, light should automatically be provided in areas where the loss of light might cause personnel hazard.

1246 Company Experience with Lighting Systems

Industrial LightingHigh pressure sodium lamps are preferred for most outdoor onshore lighting appli-cations because of their lower initial capital investment and operating costs. MV or MH fixtures should be considered for offshore locations where power is locally generated (often at lower cost/KWH) and where obstructions may shadow areas (requiring more fixtures regardless of the individual fixture output). There are some applications where only a few fixtures are required or where color rendering is of primary importance. In these situations, metal halide or color-corrected mercury vapor fixtures may be preferred.

Service Station LightingMetal halide lighting is almost exclusively used for outdoor lighting at Chevron service stations. The better color rendering properties of metal halide help to main-tain the Company image and improve sales. Normally, high pressure lighting is used for tank truck loading racks and warehouse lighting.

Roadway and Parking LotHigh pressure sodium lighting normally is preferred for roadways and parking lots.

Offshore PlatformsMercury vapor and metal halide (and occasionally high pressure sodium) lamps are used for area lighting and lighting the interiors of large buildings. Fluorescent



lighting is used indoors (and at times outdoors) for area lighting, particularly where low profile fixtures are needed because of low ceiling heights.

Control Room LightingControl rooms or other rooms equipped with CRTs should be designed with indirect lighting to reduce glare. Wall-mounted or suspended indirect fluorescent fixtures with adjustable light level controls are preferred. Fluorescent lighting with para-bolic louvers (to reduce glare) can also be used for general lighting. Incandescent spot lighting can be used for task lighting. An effort should be made to prevent light penetration from other work spaces. All surfaces in control rooms should be nonre-flective.

Aviation LightingMetal halide or color-corrected mercury vapor systems are preferred for most heli-port lighting applications on offshore platforms because of their superior quality of light. Fluorescent fixtures may be required for low profile applications. Incandes-cent fixtures equipped with long-life lamps are used for landing lights.

1250 Lighting Calculations and Fixture LayoutThe three most common methods used to determine the number of fixtures required to provide the necessary maintained illumination for an area are: the lumen method, the point-to-point method, and the iso-footcandle method. The watts-per-square foot method is used for estimating purposes very early in a project or during the concep-tual phase of a project.

Generally, the lumen method is used in calculations where fixtures are installed in an enclosed space (like a room). The point-to-point method is commonly used in calculations for outside applications where reflected light is not a factor. However, either method may be used for indoor or outdoor locations. The IES Handbook and the Westinghouse Lighting Handbook contain detailed, step-by-step processes for using these two methods.

Most lighting design done by the Company is for exterior (outdoor) lighting, prima-rily for area lighting and floodlighting. This section explains two lighting-calcula-tion methods: the watts-per-square foot method for conceptual design, and the iso-footcandle method for general outdoor applications.

1251 Area LightingArea lighting for a particular operating company location should be standardized as much as possible. Designs should produce uniform and efficient lighting levels and facilitate cost-effective maintenance.

FloodlightingThe difference between floodlighting and area lighting is the aiming angle. The greater the aiming angle, the greater the area illuminated; however, light output directly beneath the fixture will be lower. Since the objective of floodlighting is to



maintain only 1 to 2 footcandles at grade, the best method is usually to angle fixtures at 60 degrees from horizontal and install them at heights of about 25 feet.

The area illuminated by floodlights can be varied by using different beam widths. This is particularly useful when the light must be directed to a specific area where an individual lighting fixture cannot be installed. Standard floodlight beam widths are specified by NEMA as follows:

Variables in Area LightingBy understanding and properly addressing the variables discussed below, an effec-tive lighting design can be achieved.

1. Fixture Reflector. The purpose for the reflector is to direct light down, as opposed to out. Figures 1200-10 and 1200-11 are iso-footcandle tables for fixtures with and without reflectors. Since the objective of area lighting is to provide light at grade level, reflectors should be used in most applications. Figure 1200-12 provides a conversion table for lamps other than high pressure sodium lamps.

2. Mounting Height. Both Figures 1200-10 and 1200-11 demonstrate that the lower a fixture is mounted, the brighter the area directly below the fixture. However, as the fixture height is lowered, the amount of peripheral light decreases. When selecting mounting height, it should be kept in mind that the objective of area lights is to achieve a fairly high illumination level directly below fixtures, and that relatively low mounting heights facilitate maintenance.

3. Angled Mounting. Angle stanchion mount fixtures are available to direct the light to one side so that fixtures need not be directly above the area to be illumi-nated. It is more efficient to mount a fixture directly above an area, but if this is not possible, angled mounts work well.

4. Angled Reflector. Angled reflectors serve the same purpose as angled mounts. A good application for an angled reflector is for fixtures mounted adjacent to buildings. Since minimal light is needed on the side of the building, as much light as possible should be directed to the area needing illumination.

NEMA TYPE BEAM SPREAD (degrees)

1 10 - 18

2 18 - 29

3 29 - 46

4 46 - 70

5 70 - 100

6 100- 130

7 130 and up


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F candle values to MV or MH) Cour-
ig. 1200-10 Footcandle Table—Typical HPS Fixture, Standard Reflector, No Guard (See Figure 1200-12 to convert HPS foottesy of EGS Electrical Group (formerly Appleton Electric)

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Fig. 1200-11 Footcandle Table—Typical HPS Fixture, No Reflector, No Guard (See Figure 1200-12 to convert HPS footcandle values to MV or MH) Courtesy of
EGS Electrical Group (formerly Appleton Electric)


1252 Lumen Maintenance Factor (LMF)As lamps age, lumen output deteriorates (lumen depreciation). Dirt depreciation is the lamp depreciation associated with dirt on the lamp, lens, and reflector. Together, lamp depreciation and dirt depreciation constitute the lumen maintenance factor (LMF). Figure 1200-13 provides the recommended lumen maintenance factors to apply to various types of fixtures.

Fig. 1200-12 Conversion Table for HPS to MV or MH Courtesy of EGS Electrical Group (formerly Appleton Electric)

Fig. 1200-13 Lumen Maintenance Factors (1 of 2)

Type of Fixture Lumen Maintenance Factor

Incandescent

-Indoor 0.60

-Outdoor 0.70

Fluorescent

-Indoor 0.55

-Outdoor 0.60

Mercury Vapor

-Indoor 0.40

-Outdoor 0.50

High Pressure Sodium

-Indoor 0.55



ot-nd )

For example, a 70-watt HPS fixture with a standard reflector and no guard, mounted 8-feet high, will provide 10 footcandles of initial illumination in a 5-foot radius. By applying the LMF of 0.6 for HPS fixtures, the illumination level design basis is 6 footcandles (10 x 0.6) near the end of rated life. If the minimum recommended illu-mination level is 12 footcandles, two 70-watt HPS fixtures spaced 5-feet apart would provide the required illumination.

1253 Watts-Per-Square Foot MethodThe watts-per-square foot method works well to determine the appropriate number of lighting fixtures required and to estimate the total lighting loads for determining initial calculations during the conceptual phase of a project.

To use this method, a six-step process is outlined below:

Step 1. Determine the illumination level for the area(s) in question.

Step 2. Determine the total square footage of the area to be illuminated from the preliminary plot plan.

Step 3. Determine the type of lighting fixture to use from Figure 1200-1, Light Fixture Selection.

Step 4. Determine the watts per square foot from Figure 1200-14.

Step 5. Obtain the total wattage required by multiplying the watts per square foot (from Step 4) by the area to be illuminated (from Step 2).

Step 6. Determine the total number of fixtures required by dividing the total wattage required (from Step 5) by the wattage of each lamp (from Step 3).

1254 Iso-Footcandle MethodThe iso-footcandle lighting-calculation method works well for outdoor locations, but is not well suited for indoor applications. Figure 1200-15 shows an iso-foot-candle chart for a 70-watt HPS fixture with a standard dome reflector mounted at an elevation of 8 feet. Iso-footcandle charts show lines of equal footcandles that will be produced by a specific fixture at a given height. These curves are created from photometric test data, and are representative of the lamp’s actual output. Iso-focandle charts are useful as they can be superimposed on the design plot plan arelocated until satisfactory light levels are achieved. Iso-footcandle charts (IFCs

-Outdoor 0.60

Metal Halide

-Indoor 0.45

-Outdoor 0.55

Fig. 1200-13 Lumen Maintenance Factors (2 of 2)

Type of Fixture Lumen Maintenance Factor



may be hard to obtain for a specific fixture and often have to be scaled to match the plot plan. An alternative to the iso-footcandle chart is the iso-footcandle table, which is readily available from most fixture manufacturers. Using this data, iso-footcandle levels can be placed on the plot plan.

Sections 1255 and 1256 present two examples that illustrate the layout of lighting fixtures using the iso-footcandle method.

Fig. 1200-14 Chart for Determining Watts per Square Foot



1255 Fixture Layout Using Iso-Footcandle ChartsFigure 1200-16 shows a plot plan of a tank truck loading dock, including area clas-sification. The facility consists of a pump pad, an elevated valve manifold platform, an MCC, walkways, and a parking lot.

The first step for fixture layout is to determine the proper illumination levels for the various areas. The lighting levels listed in Figure 1200-17 were chosen from API RP 540, Section 6.

High pressure sodium fixtures have been selected since they have the highest lumen efficacy and adequate color rendering. The first decision is whether to use flood-lights or area lights. The pump pad and valve platform could be adequately lit with two floodlights. A better choice, however, is to use three or four area lights because a uniform light level over the entire area (including the two stairways) can be achieved. Logical locations for the area lights would be the perimeters of the pump pad and the valve platform. In particular, placing a luminaire on an 8-foot stanchion near each stairway would light both the platform and the stairs. The 8-foot height also provides ease of relamping. Using the lumen method, three 70-watt HPS lamps will provide adequate light for the pump pad and elevated platform. The next step is to use the detailed iso-footcandle method.

An iso-footcandle chart (drawn to plot-plan scale) for a 70-watt HPS fixture mounted 8-feet high is shown in Figure 1200-18. The values are for initial foot-candle levels. A lumen maintenance factor of 0.6 for HPS lamps (from Figure 1200-13) will reduce the radiated light shown on the chart by a factor of 0.6.

Pump Pad and Elevated Valve PlatformThe iso-footcandle chart (drawn to the scale of the plot plan) is now located at the top of each stairway, and one more fixture is located to provide the three fixtures called for in the lumen method. Figure 1200-19 shows the iso-footcandle lighting level of the three fixtures. One more fixture is needed near the valve wheels on the tank-side of the platform to achieve a reasonably uniform 5 footcandles (including lumen maintenance factor) on the pump pad and valve platform.

WalkwayThe walkway requires a minimum of 1 footcandle. An iso-footcandle chart (IFC) is superimposed on the plot plan to locate the fixtures along the walkway. Using 70-watt HPS fixtures mounted at 8 feet, the result is one fixture, 15 feet from the valve platform, and two more at 25-foot intervals at the loading dock area. Figure 1200-20 shows the results.

MCCNote that the walkway fixtures do not provide adequate light at the MCC where a minimum of 5 footcandles is required. Another fixture should be located to one side of the MCC. The location in Figure 1200-21 was chosen for two reasons: first, to light the face of the MCC at an angle from the side so an operator standing in front of the MCC will not receive any glare from glass-instrument faces; and second, to



Fig. 1200-15 Iso-Footcandle Chart for Stanchion Mount Fixture Courtesy of EGS Electrical Group (formerly Appleton Electric)



provide some light on the guard posts to the side of the MCC so that a person walking from the MCC to the parking area will see the posts.

Fig. 1200-16 Plot Plan for Fixture Layout Using Iso-Footcandle Charts

Fig. 1200-17 Desired Lighting Levels for Areas in Figure 1200-16

Area Lighting Level (footcandles)

Pump Pad 5

Elevated Valve Platform 5

Stairs 5

Area of Loading Dock 10

Paved Walkways 1

Instruments and Gages 5

Parking Area 1



Loading DockThe illumination level on the loading dock needs to be much higher than other areas. By inspection, the 70-watt HPS will not provide adequate lumen output per fixture. In addition, the canopy above the loading rack is 15 feet above grade. By choosing a 100-watt HPS pendant-mounted fixture with a 4-foot pendant, plus the fixture length of 1 foot, the fixture height is 10 feet above grade. Figure 1200-22 shows the IFC drawn to scale for this fixture, superimposed on the plot plan. Two fixtures are located to provide the desired 10 footcandles in the loading area. The area of the overhang normally will be occupied by a tanker truck and will only receive partial lighting.

Parking LotThe final area to be illuminated is the parking lot. Floodlights should be used for this application since the area is larger and light levels need not be uniform or high. A single, 150-watt HPS floodlight, mounted 20 feet above grade (as shown in Figure 1200-23) will provide the necessary lighting levels across the parking area and is high enough that so it will not blind people walking to the loading dock from the parking area.

1256 Fixture Layout Using Iso-Footcandle TablesIso-footcandle tables can also be used to determine fixture locations. Figure 1200-10 is an iso-footcandle table for a 70-watt HPS fixture with a reflector. The table indicates the amount of light at grade level from a light source mounted at a given height.

Fig. 1200-18 Diagram of Iso-Footcandle Chart for 70 Watt HPS Plot-Plan Scale


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Fig. 1200-19 Pump-Pad Platform Lighting Level

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F
ig. 1200-20 Walkway Lighting Levels

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F
ig. 1200-21 MCC Lighting Levels


When using iso-footcandle tables, the best method to overlap light output from different sources must be determined in order to achieve desired light outputs. For instance, assume it is necessary to light a circle of 5-foot radius to 5 footcandles. One 70-watt HPS fixture with a reflector, mounted at 8 feet, will light a 5-foot radius circle to 6 footcandles (after a 60% maintenance factor is applied). See Figure 1200-24 (top). Therefore, one fixture will fulfill the requirement.

Assume the area to illuminate is 10 feet by 20 feet. Two 70-watt HPS fixtures, spaced 15 feet apart, will do the job. When two fixtures are adjacent, the resulting footcandle level is the sum of the contributions from each fixture. For example, the sum of the contributions at the center of the 10-foot by 20-foot area is approxi-mately 6 footcandles. See Figure 1200-24 (bottom).

To illustrate the iso-footcandle table method, Figure 1200-25 shows a plot plan where two gasoline pumps are to be installed in an area adjacent to a pipeway. The area classification is shown by hashed marks representing a Class I, Division 2, Group D area. Two new walkways and a small parking lot are to be added. The only existing lights in the area are the streetlights on the road and the floodlights by the existing pump station. A lighting survey has shown that the existing illumination where the new facilities are to be installed is essentially zero. To determine the lighting levels in Figure 1200-25, refer to API 540, Section 6.

High pressure sodium fixtures are used for this application since they have the lowest life-cycle cost and adequate color rendering for the application.

To design the lighting system, divide the new area into four sections: (a) the parking lot, (b) the walkways, (c) the pumps, and (d) the pump manifold.

Parking LotA 250-watt, HPS widebeam floodlight, mounted at a height of 25 feet and aimed at 60 degrees, illuminates an oval shaped area 70 feet by 50 feet to approximately 1 footcandle. Because of the lumen maintenance factor, two floodlights will be required to adequately light the 75-foot by 65-foot parking lot to an illumination level of about 1 footcandle (2 x 1 fc x 0.6 = 1.2).

Mounting both floodlights on a single pole (compared to two poles) in the middle of the right side of the parking lot will reduce costs. The fixtures are aimed at 60 degrees to the opposite corners of the parking lot. There may be shadow areas that may not achieve 1 footcandle, but most of the lot will be adequately illuminated.

With most multiple floodlight designs, it is virtually impossible to avoid shadow areas and still achieve a cost-effective design. Lighting design pamphlets available from major lighting manufacturers can be used as guides.

WalkwaysFor standardization purposes, 70-watt HPS fixtures mounted at a height of 8 feet will be used throughout the facility. Standardization simplifies the design, construc-tion, and maintenance of the facility. From Figure 1200-10, about 1 footcandle can be maintained (including the lumen maintenance factor) for a horizontal distance of


Electrical Manual

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September 1990

F
ig. 1200-22 Loading Dock Lighting Levels

Electrical Manual

1200 Lighting


September 1990

F
ig. 1200-23 Parking Lot Lighting Levels


12.5 feet. Fixtures will be separated by 25 feet. One fixture is installed on the paved walkway, 12.5 feet from the parking lot. Four more are installed along the walkway toward the new pumps, 25 feet apart. Along the 225 foot walkway towards the pump station, a fixture is installed 12.5 feet from the intersection of the two new walkways and eight more are installed along the walkway towards the pump station, 25 feet apart.

PumpsSeventy-watt HPS fixtures spaced 12.5 feet apart (one per pump) will provide the required 5 footcandles of illumination.

Fig. 1200-24 Lighting Level at a Radius of 5 ft. Circle (top) and Lighting Level at Center of 10 ft. by 20 ft. Area (bottom)


Electrical Manual

1200 Lighting


September 1990

F
ig. 1200-25 Iso-Footcandle Plot-Plan: Example Showing Iso-Footcandle Table Method


Manifold AreaThe general area to be illuminated around the pump is approximately 50 feet by 50 feet. One 250-watt HPS floodlight on a 25-foot pole will sufficiently light the general area to approximately 1 footcandle and keep the fixture out of the classified area.

1260 Maintenance ConsiderationsIf a regularly scheduled maintenance program is not followed, the effectiveness of a lighting system can be substantially reduced. Proper maintenance is usually more economical than allowing the system to operate at low efficiency.

A good maintenance program involves: (1) replacing lamps, (2) cleaning fixtures, and (3) cleaning lighted surfaces.

Replacing Lamps (Relamping)Two different approaches may be taken in relamping programs: (1) replace lamps as they extinguish, or (2) replace all lamps at one time (group replacement). The first approach, individual lamp replacement, is usually the least cost-effective method. The labor portion of the relamping program typically dominates the total cost. When the labor cost is not the largest portion of relamping cost, the first approach is the more economical (e.g., on offshore platforms.)

A group replacement scheme can be developed for a given installation by consid-ering the cost of labor and lamps, lamp life, and the effect of work interruptions. A commonly used criterion for group replacement is: When 20% of the original lamps have failed, the entire installation is relamped. This approach cannot be used if fixtures provide light for specific locations.

The time between replacements may vary somewhat because of variations in system voltage and operating schedules. Overvoltage or undervoltage should be suspected if the replacement interval is several months shorter than normal.

Cleaning FixturesIn some instances, dust and other foreign material on lighting equipment can reduce the lighting level by 30% in only a few months. The type of ventilation and cleanli-ness of the surrounding area determine the required cleaning intervals. It is impor-tant to clean fixtures regularly. If fixture cleaning is coordinated with group lamp replacement, maintenance costs usually can be kept to a minimum.

Fig. 1200-26 Desired Lighting Levels for Iso-Footcandle Areas in Figure 1200-25

Area Lighting Level (footcandles)

Pump Pad 5

Pump Manifold/General Area 1

Walkways 1

Parking Lot 1



Cleaning Lighted SurfacesCleaning interior lighted surfaces usually is an important maintenance factor. If an illumination survey indicates less than the design level illumination after lamp replacement and fixture cleaning, the lighted surfaces may need painting or cleaning. However, a check should be made first to insure that low voltage is not the problem.

1270 Glossary of TermsAverage Luminance: The average brightness of a luminary at a given angle, expressed in candles per square inch or footlamberts.

Ballast: An electromagnetic device used to control starting and operating condi-tions of electric discharge lamps.

Brightness: See luminance.

Brightness Ratio: See luminance ratio.

Candela: Unit of luminous intensity (preferred over the term candle).

Candle: Unit of luminous intensity (candela is preferred).

Candlepower: Luminous intensity expressed in candelas.

Dekalux: 10 lux (0.929 footcandles.)

Electric discharge lamp: A lamp in which light is produced by passing an arc current through a vapor or gas.

Fixture: A full assembly of lamp, ballast (if necessary), socket, holder, diffuser, lens and guard. The term luminaire is used interchangeably with fixture.

Footcandle: The unit of illumination used in the United States. It is equal to the illumination of a surface area of 1 square foot on which there is a uniformly distrib-uted flux of 1 lumen. One footcandle equals 10.76 lux or 1.076 dekalux.

Footlambert: The unit of luminance (brightness).

Glare, Direct: Glare resulting from high brightness in the field of vision.

Glare, Disability: Glare which reduces visibility and causes discomfort.

Glare, Discomfort: Glare that produces discomfort, but does not necessarily reduce visibility.

Illumination: The quantity of light (lumens) falling on a given surface area.

Lumen: The unit of luminous flux. The amount of light flux radiated into a solid angle by a uniform light source. In practice, it is the unit of light output that lamp manufacturers identify on their specification sheets.

Lumen maintenance: Data, usually given in graph form, showing the effect of age on the output of a lamp.



Luminaire: A complete lighting unit which consists of a lamp with components to distribute light, the parts to protect and position the lamps, and the parts to connect the lamps to the power supply.

Luminance: Brightness, the luminous intensity of a surface in a given direction, per unit of projected area of the surface.

Luminance ratio: The ratio of brightness between any two areas in the field of vision.

Luminous Efficacy: The ratio of luminous flux (lumens) output to electrical power (in watts) input for a lamp, expressed in lumens per watt.

Luminous flux: The time rate of flow of light, expressed in total output of a light source in lumens.

Lux: The International System Unit (SIU) of illumination, equal to the illumination on a surface area of 1 square meter on which there is a uniformly distributed flux of 1 lumen. One lux equals 0.0929 footcandles.

Mounting height: The distance from the work plane to the center of the lamp.

Reflectance: The fraction of the total luminous flux incident on a surface that is reflected.

Work plane: The plane where the task under consideration is located and where the recommended illumination is required.

1280 ReferencesThe following references are readily available. Those marked with an asterisk (*) are included in this manual or are available in other manuals.

1281 Model Specifications (MS)There are no specifications for this section.

1282 Standard DrawingsThere are no standard drawings in this guideline.

1283 Data Sheets (DS), Data Guides (DG), and Engineering Forms (EF)*ELC-EF-484 Lighting Schedule

*ELC-EF-599 Lighting Standards, Flood Ltg. Fixtures & Mtg. Details

*ELC-EF-600 Standard Lighting Poles, Fixtures, and Receptacle Mountings



,

1284 Other ReferencesAmerican National Standard Practice for Industrial Lighting (ANSI/IES RP-7)

American National Standards Practice of Office Lighting (ANSI/IES RP-1)

*American Petroleum Institute RP 14F, “Design and Installation of Electrical Systems for Offshore Production Platforms”

*American Petroleum Institute RP 540, “Recommended Practice for Electrical Installations in Petroleum Processing Plants”

Code for Safety to Life from Fire in Buildings and Structures, ANSI/NFPA No. 101

Electrical Construction Guidelines for Offshore, Marshland, and Inland Locations, revised August 1988, CUSA Eastern Region Production Department

ANSI/IEEE Std 45, “IEEE Recommended Practice for Electric Installations on Shipboard”

IES Lighting Handbook, 1984 Reference Volume and 1987 Application Volume

IES RP 12, “Recommended Practice for Marine Lighting”

National Electric Code, ANSI/NFPA 70

U.S. Coast Guard Regulations, Federal Register Title 33, July 1, 1987, “Pollution Prevention - Regulations for Marine Oil Transfer Facilities,” Paragraph 154.570Lighting, and Paragraph 155.79, Deck Lighting. Washington, DC

Westinghouse Lighting Handbook, Revised May, 1978 (No longer published)


12 lighting

Documents

lighting design

selection of lighting

selection of lighting

lighting system design

appropriate lighting

acceptable lighting

design considerations

influence fixture selection