Critical Power: Circuit Protection in Health Care Facilities

Sponsored by:

Today’s Webcast Sponsors:

Neal Boothe, PE, exp US Services Inc., Maitland, Fla.

James Ferris, PE, TLC Engineering for Architecture, Orlando, Fla.

Moderator: Amara Rozgus, Editor in Chief, Consulting-Specifying Engineer and Pure Power

Presenters:

1. The audience will understand the applicable codes: NFPA 70: National Electrical Code, Article 517, NFPA 99: Health Care Facilities Code, and NFPA 110: Standard for Emergency and Standby Power Systems.

2. Attendees will understand the coordination, overcurrent, short-circuit, and ground-fault protection issues for health care facilities.

3. Viewers will learn about feeder protection design requirements for health care facilities.

4. Viewers will learn about branch protection design requirements for health care facilities.

Learning Objectives

Critical Power: Circuit Protection in Health Care Facilities

Applicable Codes• National Electrical Code (NEC), NFPA 70,

Article 517• Used the 2008 Edition here

• NFPA 99, Health Care Facilities Code• Used the 2012 Edition here

• NFPA 110, Standard for Emergency and Standby Power Systems

• Used the 2013 Edition here

Quick Thoughts on These Codes• National Electrical Code

– By far most specific requirements– Focuses on Electrical Safety– Chapters 1 – 4 Still Apply to Hospitals– Article 517 – Health Care Facilities adds new

requirements– Article 700 – Emergency Systems – Still

applies to Health Care

Quick Thoughts on These Codes• NFPA 99, Health Care Facilities Code

– Covers many more topics than electrical– Chapter 6 – Electrical Systems

• 6.3.2.1 – NFPA 99 defines performance required to ensure safety. NEC defines ways systems must be installed to achieve desired performance.

• There is a great deal of referencing between NFPA 99 and NEC Article 517

– Chapter 10 – Electrical Equipment• Applies more to manufacturers than designers

Quick Thoughts on These Codes• NFPA 110, Standard for Emergency and

Standby Power Systems– Concerned with Generator, ATS, etc.– Not written around just health care– Hospitals = Level 1 System . . . But so are

other building types

Feeder & Branch Circuit Protection• NEC 517.12 – Except as modified in this

article, wiring methods shall comply with the applicable requirements for Chapters 1 through Chapter 4 of this Code.

• So, you can’t just look at Article 517– It adds new requirements

Feeder & Branch Circuit Protection• Feeders – Not too much different for

hospitals– Panels serving critical care areas

• Branch circuits – Very specific requirements for hospitals– Patient care versus Non-Patient care– Emergency versus Others

What is a Patient Care Area?• Per NEC 517.18 & 517.19, two types:

1. General Care – Patients in contact with ordinary appliances

• Medical/surgical rooms, exam rooms, etc.2. Critical Care – Patients subject to invasive procedures

• ICU, ORs, Catheterization Labs, Labor/Delivery, Coronary Care, Trauma, Emergency Care, etc.

• Note: Areas such as nurse stations, medical prep, nourishment, clean, soil, etc. aren’t Patient Care Areas

Hospital Feeder Circuit Protection• For Panels Serving Critical Care Areas

– Per NEC 517.19, if metal conduit, MI, or MC cable is used

• Ground Panel to Feeder via:– Grounding bushing– Threaded hubs– Other approved devices

• Any other areas (Not Critical Care)– No specific requirements for hospitals

• Recommendation – Use Metal Conduit

Hospital Branch Circuit Protection• Two Main Thoughts . . .

– Redundant grounding required for all patient care area branch circuits – NEC 517.13 (a) & (b)

– Mechanical protection of all emergency branch circuits – NEC 517.30 (C) (3)

• This includes patient care areas and non-patient care areas

• Typically done by non-flexible metal conduit (EMT usually).

Patient Care Area (General or Critical Care)

• Emergency Circuits (Life Safety & Critical)1. Require redundant grounding – NEC 517.13

• Grounding conductor and metal conduit2. Require mechanical protection 3. This means conduit must be metal

• Schedule 80 PVC would meet #2 but not #1• Hospital grade flex would meet #1 but not #2

Patient Care Area (General or Critical Care)

• Normal or Equipment System Circuits1. Also require redundant grounding2. Mechanical protection not required

• This allows some flex conduit (hospital-grade flexible cable)

• Be careful circuiting– Does circuit serve both patient care and

non-patient care area?– More stringent requirements will apply

Exceptions to Mechanical Protection• Non-Patient Care Areas

– Schedule 80 PVC– In Concrete

• Schedule 40 PVC• Flex non-metallic or jacketed metallic raceway• Jacketed metallic cable

Exceptions to Mechanical Protection• Patient Care Areas

– Flexible metal & metal sheathed cable in:• In listed medical headwalls• In listed office furniture• Fished into existing walls or ceilings• Necessary for flexible connection

Hospital Grade Flexible Cable

• A “cross” between AC and MC Cable– Has a grounding conductor (like MC)– Sheath is ground rated (like AC)

In a Non-Patient Care Area• Emergency Circuits

1. Redundant grounding not required2. Still require mechanical protection3. Allows more flexibility of installation – but #2

still leads to metal conduit often• Normal Circuits

1. Redundant grounding not required2. Mechanical protection not required3. This allows much more flexibility of installation

Distribution Protection

Short Circuit Protection

Selective Coordination

Arc Flash Protection

Short Circuit Protection • Input Data• Calculations• Equipment Ratings• Nameplates

Short Circuit Input Data• Utility Fault Contribution• Generator Fault Contribution• Motor Contribution• Feeder Size & Lengths• Transformer Size & Impedance• *If Allowed by Authority Having Jurisdiction –

Current Limiting devicesResults: Short Circuit Fault Available at locations

throughout the distribution

Fault Calculations on Generator or Utility

• Must Consider both sources as potential source of fault current.

• Utility company will provide a letter indicating the available fault at the service

• Generator manufacturer's can provide the fault output of each engine

• Sometimes both of these are in parallel!

Short Circuit Calculation Results Example

BUS V3-Phase Fault on Utility (A)

3-Phase Fault on Generators (A)

Largest Available Fault

AHU 2-1 480 9650.3 9754.2 9754ATS CR1 480 44949.2 44494.5 44949ATS EQ2 480 39695.3 43448.5 43449CH2ORDPB 480 32965.1 33894.8 33895CL2A 208 5598.2 5595.9 5598LSH1 480 21621.5 21106.3 21622NH3 480 20523.9 21006.4 21006

* Also need to calculate the Single Line to Ground as on Generator power that is often the worse case.

Short Circuit Ratings – in the Field• AIC: Amps Interruption Current

– Breakers & Fuses have this• WSR: WithStand Rating –

– Enclosures / Equipment such as an Automatic Transfer Switch

• SCCR: Short Circuit Current Rating– UL 508A / NEC 409.110 requires Industrial

Control Panels to be labeled with SCCR

Short Circuit Ratings – in the Field• Review Equipment

Nameplates in the field to ensure they meet the requirements of the Short Circuit Calculations

Air Handling Unit Nameplate

Short Circuit Ratings – What needs one?

SwitchboardsAutomatic Transfer Switches

Panelboards

Motor Controllers

Electrical Disconnects

Elevator Controllers

Pump Starters

Industrial Control Panels

Adjustable Speed Drives

Selective Coordination• NEC Definition of Selective Coordination

Selective Coordination Goal1. Protect other circuits by ensuring the

breaker in trouble trips first2. Protecting equipment and infrastructure

a. Transformersb. Cablesc. Motorsd. Generators

Selective Coordination Example

A 60A Main Circuit Breaker Panelboard Serves several 20A Circuits

A fault on the 20A circuit breaker should not trip the 60A breaker

Selective Coordination Process

Select Overcurrent

Device

Check Coordination

Adjust Distribution

Selective Coordination Demonstration• Use Time-Current

Curves to demonstrate Selective Coordination

Current

Time

ExampleExample of a typical time-current plot where all the breakers for a particular distribution are shown in a single plot.

Selective coordination occurs where there is space between the breakers.

Selective Coordination 0.1s Debate

• NEC does not indicate a time requirement for Selective Coordination.

• NFPA 99, Health Care Facilities, 2012 Edition indicates that in a hospital Selective Coordination Starts at 0.1 Second

Selective Coordination 0.1s DebateFor Health Care facilities

only, where 2012 is applicable

• Overcurrent protection does not have to selectively coordinate from 0 to 0.1s

• Disclaimer – discuss this with your local AHJ

Overcurrent Protection in this area must selectively coordinate

Overcurrent Protection in this area should, but does not have to coordinate

Ground Fault Protection• Hospitals require two levels of

ground fault protection

• Separation must be 6 cycles per NEC, Article 517

• Typical Ground Fault Plot shown at the right

Arc Flash & Personnel Protection

Short Circuit

Available

Overcurrent Device

Settings

Arc Flash Energy

Available

Short Circuit, Selective Coordination have a direct impact on how much energy is available in an Arc Flash Event.

Learning Objective Summary• Applicable Codes• Feeder & Branch Circuit Protection• Redundant Grounding at Patient

Locations• Short-Circuit Calculations• Selective Coordination• Arc Flash

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Archive:• Within 7 days, an archive with Q&A will be posted• We will send an email to registered attendees with hyperlink• Can also access from www.csemag.com home page

Neal Boothe, PE, exp US Services Inc., Maitland, Fla.

James Ferris, PE, TLC Engineering for Architecture, Orlando, Fla.

Moderator: Amara Rozgus, Editor in Chief, Consulting-Specifying Engineer and Pure Power

Presenters:

Thanks to Today’s Webcast Sponsors:

Critical Power: Circuit Protection in Health Care Facilities

Sponsored by: