y our d ata c enter p artner © 2009 tier4 data center group, inc. all rights reserved. electrical...

© 2009 Tier4 Data Center Group, Inc. All rights reserved.

Your Data Center Partner

Electrical Safety and Your Data Center

Martin Conroy, CPQ

AFCOM Omaha Chapter Meeting April 1, 2009



ELECTRICAL SAFETY HAZARDSArc-Flash and Shock Hazard



This presentation is intended to serve as an explanation and introduction to electrical safety. It is not intended to substitute for expert analysis or professional consultation. Information presented is accurate to the best of our knowledge and is based on review of industry-accepted data and studies.

Tier4 Data Center Group assumes no liability or responsibility whatsoever in connection with any use of this information

Each site requires engineering study to determine risk and hazard levels.

Disclaimer



Questions Do you have workers install power cables on energized panels?

(example: running new circuit for server rack?) Do you have work/modifications performed on energized electrical

systems? (example: upgrading power, UPS, generator systems?) Do you commission live electrical systems (example: UPS, batteries,

generators, PDU’s) Do your UPS vendors service equipment while energized? Do your employees have unrestricted access to areas where

energized electrical equipment is open or being worked on? Is you data center designed to allow electrical equipment to be de-

energized without shutting down the IT loads? Do you understand the potential risks, hazards and liabilities

associated with these questions?



Observations Compliance with existing safety laws may

require you to change how you manage, operate and design your data center

Data centers require large amounts of power and this increases safety risks

Data centers do not like to shut down and this increases electrical safety risks

Many people choose to ignore, deny or dismiss their responsibilities when it comes to electrical safety and this increases risks and liabilities

Request: Please do not shoot the messenger!



Electrical Facts

• Electricity will take path of any resistance –including you!!

• Electric current will always return to the source (utility transformer or separately derived source)

• Electricity flows in complete paths, if you complete the path you will get shocked!

• The earth is a ground fault current path!

The earth can conduct enough electrical current to electrocute a person

The earth shall not be considered as an effective ground-fault path. (An earth ground could or could not cause overcurrent devices to open)



Electrical Statistics Approximately 30,000 workers receive electrical shocks each

year 3600+ disabling electrical shock injuries per year 2000+ workers are sent to burn centers due to arc-flash

injuries/year 1000+ electrical workers die each year from workplace

accidents 97% of all electricians have been shocked or injured on the

job. Estimated 10 arc-flash incidents / day in USA 60% of workplace deaths are due to burn injuries Medical costs can exceed $4M/person for severe electrical

burns, total costs per electrical incident can exceed $15 million

*Source NFPA, National Safety Council, Bureau of Labor Statistics, Littlefuse



Electrical Statistics

The National Safety Council estimates that between 600 and 1,000 people die each year from electrocution. Of those killed with voltages less than 600V, nearly half were working on “exposed” energized circuits at the time the fatal injury occurred. Electrocution continues to rank as the fourth highest cause of industrial fatalities (behind traffic, violence/homicide, and construction incidents).

In year 2002 work injuries cost Americans $ 146.6 Billion



Electricity Risk Areas

Electrical Shock Hazards» Existing standards and practices address many of these

risks

Arc Flash/Burn Hazards» Existing Standards and practices address some these

risks

Arc Blast Hazards» Existing standards and practices address very few of

these risks



Risk issues

Both employer and employee risks Injury or death to personnel Rehab / disabilities OSHA fines and citations Lost / damaged equipment Unplanned outages and repairs Increased insurance and worker

compensation costs Expensive lawsuits



Shock Hazards

Most personnel are aware that there is a danger of electrical shock, even electrocution. It’s the one electrical hazard around which most electrical safety standards have been built.

However, few people really understand just how little current is required to cause injury, even death. Actually, the current drawn by a 7.5W, 120V lamp, passing across the chest, from hand-to-hand or hand-to-foot, is enough to cause death by electrocution.



Shock Hazards The human body will conduct electrical current! A circuit path

can be through both arms, through an arm or leg to ground, or through any body surface to ground. There is a certain current level at which an individual cannot voluntarily release from the circuit. This is the "no let go current" from which burns and death by electrocution can result.

Studies have shown that the perception of electrical shock begins when the current through the affected parts of the body is about 0.002 amperes. When the current increases to about 0.015 to 0.020 amperes, it becomes impossible to let go of the circuit. At higher values of current, e.g. above about 0.100 amperes, ventricular fibrillation and/or heart stoppage will cause certain death.



Arc-Flash Hazards Arc-Flash is an unexpected sudden release of

heat and light energy produced by electricity traveling through air.

This explosive condition includes a broad spectrum of electromagnetic energy, plasma, fragments and a spray of molten materials.

Temperatures at the arc terminals can exceed 35,000 deg F, (4 times hotter than the surface of the sun)

Air and gases surrounding the arc are instantly heated and the conductors are vaporized causing a pressure wave called an Arc Blast.



Arc-Flash Hazards

Burns from direct heat exposure or clothing ignition. At distances of more than 10 feet, arc flash is capable of causing serious burns requiring skin grafts.

Loss of eyesight from UV light emitted by vaporized metal

Death Equipment damage/outages Fire



Burn Hazard First-degree burns are limited to the top layer of skin:

» Signs and symptoms: These burns produce redness, pain, and minor swelling. The skin is dry without blisters.

» Healing time: Healing time is about 3 to 6 days; the superficial skin layer over the burn may peel off in 1 or 2 days.

Second-degree burns are more serious and involve the skin layers beneath the top layer:

» Signs and symptoms: These burns produce blisters, severe pain, and redness. The blisters sometimes break open and the area is wet looking with a bright pink to cherry red color.

» Healing time: Healing time varies depending on the severity of the burn



Burn Hazard Third-degree burns are the most serious type of

burn and involve all the layers of the skin and underlying tissue:

» Signs and symptoms: The surface appears dry and can look waxy white, leathery, brown, or charred. There may be little or no pain or the area may feel numb at first because of nerve damage.

» Healing time: Healing time depends on the severity of the burn. Deep second- and third-degree burns (called full-thickness burns) will likely need to be treated with skin grafts, in which healthy skin is taken from another part of the body and surgically placed over the burn wound to help the area heal.

Internal burns – muscle, organs, veins, » Could continue to burn after shock event due to internal heating



PhotosFollowing pictures are graphic examples of electrical

shock and burn injuries.



Photos



Arc-Flash Metrics

The amount of instantaneous heat energy released by an Arc-Flash is called incident energy.

Expressed in calories per square centimeter (cal/cm²)

Five Hazard Risk categories

(HRC 0 to 4) Calculations are based on working

distance of 18” from arc terminals



Incident Energy Incident Energy

Result

0.0033 Amount of energy sun produces in 0.1 sec at the earth surface at the equator

1 Finger tip exposed to cigarette lighter flame for one second

1.2 Energy that will instantly cause 2nd degree burn to bare skin

4 Energy that will instantly ignite a cotton shirt

8 Energy that will cause incurable 3rd degree burn to bare skin



HRC - Hazardous Risk Categories

Incident Energy

cal/cm²

Hazard Risk Category

0 to 1.2 0

1.21 to 4 1

4.1 to 8 2

8.1 to 25 3

25.1 to 40 4



Arc-Blast Hazards

High energy arc-flash heats and expands air Vaporized copper expands 67,000 times its

mass when it changes from solid to vapor Blast pressure can exceed 2000 pounds per

square foot. Blast speed can exceed 700 MPH Injuries from falls or collision with equipment.

An arc fault of 50 kA can accelerate a nearby worker at speeds of up to 110 mph.



Arc Blast Hazards

Hearing damage or total hearing loss from ruptured eardrums. The sound of a blast can exceed 160 dB. (Sounds above 140 dB cause hearing loss even with protective equipment.)

Lung collapse or scarring from the shock wave and inhalation of vaporized metal

Memory loss and other neurological damage from concussion

Injuries from flying shrapnel Death Equipment damage



Electrical Safety Compliance

NFPA 70 National Electrical Code

NFPA 70EElectrical Workplace Safety

NFPA 70BElectrical Equipment

Maintenance

Law, rules,

regulation

OSHAInstallation codes, safe products, safe installation, inspections and enforcement

Policies, procedures, training, risk analysis, qualified workers, PPE

Scheduled maintenance, testing and replacement per manufacture and industry best practices



OSHA

Occupational Safety and Health Administration

OSHA Standard 29 CFR Part 1910, Subpart S addresses electrical safety work practices and maintenance requirements.

OSHA is the “Shall” with regards to electrical safety

OSHA is the law!



OSHA General Duty Clause

29 U.S.C. § 654, 5(a)1: Each employer shall furnish to each of his employees employment and a place of employment which are free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees."

Each employee shall comply with occupational safety and health standards and all rules, regulations and orders issued pursuant to this Act which are applicable to his own actions and conduct.



OSHA General Duty Clause

29 U.S.C. § 654, 5(a)2: Each employer shall comply with occupational safety and health standards promulgated under this act.

29 U.S.C. § 654, 5(b): Each employee shall comply with occupational safety and health standards, and all rules, regulations, and orders issued pursuant to this Act which are applicable which are applicable to his own actions and conduct.



NFPA 70 – 2008 National Electrical Code

90.1 Purpose

» (A) Practical Safeguarding. The purpose of this Code is the practical safeguarding of persons and property from hazards arising from the use of electricity.

» (B) Adequacy. This Code contains provisions that are considered necessary for safety. Compliance therewith and proper maintenance results in an installation that is essentially free from hazard but not necessarily efficient, convenient, or adequate for good service or future expansion of electrical use.

» (C) Intention. This Code is not intended as a design specification or an instruction manual for untrained persons.



NEC and Standards

NEC 110.2 Approval - Equipment must be approved

NEC 110.3 – Covers listing of equipment (UL, ETL, CSA, etc)

NRTL – Nationally Recognized Testing Laboratory - UL, ETL, CSA



NFPA 70 – 2008 National Electrical Code

Article 110.16 Flash Protection. Electrical equipment, such as switchboards, panelboards, industrial control panels, meter sockets enclosures, and motor control centers that are in other than dwelling occupancies and are likely to require examination, adjustment, service, or maintenance while energized shall be field marked to warn qualified persons of potential electrical arc flash hazards. The marking shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment.

FPN No. 1 - NFPA 70E-2009 Safety standardFPN No. 2 - ANSI Z535.4-1998 Product safety signs



NFPA 70E-2009

Standard for Electrical Safety in the Workplace, provides assistance in determining severity of potential exposure, planning safe work practices, and selecting personal protective equipment.

Requires all information on labels including boundaries and PPE requirements.

Concentrates on safety requirements to protect employees.

This covers the “how” of electrical safety



NFPA 70B 2006 – Recommended Practice for Electrical Equipment

Maintenance

This recommended practice applies to preventive maintenance for electrical, electronic, and communication systems and equipment and is not intended to duplicate or supersede instructions that manufacturers normally provide.

Systems and equipment covered are typical of those installed in industrial plants, institutional and commercial buildings, and large multifamily residential complexes.



OSHA and NFPA requirements

Electrical Hazard Analysis» Analysis shall address all potential electrical hazards

including shock, Arc-Flash, Arc-Blast, and burns.

» NFPA 70E Article 110.8(B)(1) requires electrical hazard analysis within all areas of the electrical system that operate at 50 volts or greater.

» The analysis will determine work practices, protection boundaries, exposure levels, personal protective equipment and other procedures.

» The analysis provides the required information necessary for equipment labeling.



IEEE Std 1584-2002 (Guide for Performing Arc-Flash Hazard

Calculations) IEEE 1584-2002 was developed to help protect people

from arc-flash hazard dangers. The predicted arc current and incident energy are used in selecting appropriate overcurrent protective devices and personal protective equipment, as well as defining safe working distance.

Since the magnitude of the arc current is inherently linked with the degree of arc hazard, the arc is examined as a circuit parameter. Furthermore, since estimation are often useful, simple equations for predicting ballpark arc current, arc power, and incident energy values and probable ranges are presented in this work



Four Protection Boundaries

Flash Protection Boundary (FPB)Safe approach distance from energized parts <1.2 cal/cm²

Three shock approach boundaries1. Limited Approach Boundary

Unqualified persons must be accompanied by a qualified person and use PPE

2. Restricted Approach BoundaryOnly qualified persons are allowed in this area and must

use PPE

3. Prohibited Approach BoundaryWork in this area considered the same as making direct

contact with energized parts. Only qualified persons are allowed in this area and must use PPE



IEEE 1584 Level of PPE

This is the minimum level of Personal Protective Equipment in calories per centimeter squared, as evaluated in IEEE Standard 1584, with the intent to protect the worker from the thermal effects of the arc flash at 18 inches from the source of the arc

Note: Does not address the arc blast hazards



Sample Table Min Incident

Energy, cal/cm^2

Max Incident Energy,

cal/cm^2

Risk Category

Required Min Rating

of PPE, cal/cm^2

0 1.2 0

1.2001 4 1 4

4.001 8 2 8

8.001 25 3 25

25.001 40 4 40

40.001 and above Not Available

Not Available



PPE Personal Protective Equipment Provides shock and arc flash burn protection Suits are rated in cal/cm² Electrically rated shoes, gloves Resistant to flame and

self-extinguishing Thermal insulation from

heat radiation Over 40 cal = arc flash/blast

that you cannot be protected

from, you could be killed!



Typical PPE ExamplesCategory Energy

LevelTypical PPE

0 N/A Natural fiber ( cotton / wool ) long sleeve shirt & pants, safety glasses, hard hat, V-rated gloves

1 5 cal FR shirt and pants, safety glasses, hard hat, V-rated gloves

2 8 cal FR shirt and pants, face shield, hard hat, ear canal inserts, V-rated and leather gloves, leather work shoes, cotton underwear

3 25 cal FR coverall over FR shirt and pants, flash suit hood, ear canal inserts, V-rated and leather gloves, leather work shoes, cotton underwear

4 40 cal Flash suit over FR coverall over FR shirt and pants, flash suit hood, ear canal inserts, V-rated and leather gloves, leather work shoes, cotton underwear



Steps to compliance Understand and follow NFPA and OSHA guidelines

» Allow only qualified individuals to perform work or be in vicinity of work

» Establish a Safe Work Condition and work on system components de-energized whenever possible

» Develop an Electrical Safety Policy and Program» Perform shock hazard and flash hazard analysis,

available fault currents, hazard risks, shock and flash protection boundaries

» Develop formal training for equipment operators, service technicians, vendors and any other employee that might come in contact with the identified hazard

» Label equipment with required information» Use appropriate PPE, insulated tools, barriers, etc.» Use live work permits



Live Work Permits

OSHA Standards require all work to be done with equipment de-energized except for two conditions

What qualifies for “live work”? » Testing (power must be on to take measurements)» If the risk involves MORE than one life, then you probably have

the justification to work on live equipment.» Need valid justification for live work.» Financial and convenience reasons are not valid justifications for

live work ! *

If the equipment must be worked on while energized, then you need a live work permit.

* per OSHA interpretation letter



Arc-flash Study



Arc Flash Study



Arc-Flash Study



Qualified Individuals

Qualified workers must be knowledgeable on the equipment and the hazards that exist and receive documented training.



Employee Training

An essential element in an effective electrical safety program is training. From both a legal and effective point of view, training records are important. Training should be based on the program and procedures in place within an organization. The training should focus first on increasing knowledge and understanding of electrical hazards and second on how to avoid exposure to these hazards. As a person completes a specific segment of training, a record should be established and maintained. An electrical safety program should accomplish the following objectives: Make personnel aware of the rules, responsibilities and procedures for working safely in an electrical environment;



Documentation

Demonstrate the employer’s intention to fully comply with federal law;

Document general requirements and guidelines to provide workplace facilities free from unauthorized exposure to electrical hazards;

Document general requirements and guidelines to direct the activities of personnel, who could be either deliberately, or accidentally, exposed to electrical hazards;

Encourage, and make it easier for each employee to be responsible for his or her own electrical safety self-discipline.



Detailed labels



Data Center Compliance IssuesMajor issue: Is “Live Work” justifiable ?

Option 1: » Shut down data center when doing electrical work and maintenance

Option 2: » Design data center so that majority of electrical system can be bypassed

and de-energized without having to shut down IT equipment

» Have well documented MOP’s – Methods of Procedures to perform bypass and shut down procedures.

Option 3: IF “Live Work” can be justified » Will have to limit size of electrical systems to HRC of 4 or less

» Must follow all applicable electrical safety requirements

» Must have “Live Work” permit, PPE, qualified workers, safety policies & program, MOP’s, Arc-Flash study, proper labeling, etc.



Summary

Employers/owners have requirements including providing appropriate PPE

Employees have requirements Contractors have requirements Cannot transfer liabilities and responsibilities Get trained! Perform Electrical Hazard Analysis Use appropriate PPE Keep unqualified persons out of hazard areas



Conclusions Data Center industry will learn to adjust and adapt to

the rules, requirements and laws concerning electrical safety.

Compliance with existing regulations and standards will increase the reliability of your data center.

Compliance will increase the safety of your data center.

In the end, let me leave you with one thought:

“Human life trumps everything else”



Resources

www.osha.gov IEEE 1584 NFPA 70E 2009 NFPA 70B NFPA 70 NEC



Thank you

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