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Critical Power: Circuit Protection in Health Care Facilities


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Health care facilities and hospitals have more stringent circuit protection requirements than conventional building electrical systems. Because of the unique constraints of health care facility electrical systems, design engineers must ensure these demanding requirements are met. However, codes adopted in many jurisdictions don’t provide a significant amount of guidance regarding feeder and branch circuit design for health care facilities. Engineers must understand and apply circuit protection best practices especially when designing electrical systems in health care facilities.

Published in: Education

Critical Power: Circuit Protection in Health Care Facilities

  1. 1. Critical Power: Circuit Protection in Health Care Facilities Sponsored by:
  2. 2. Today’s Webcast Sponsors:
  3. 3. 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:
  4. 4. 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
  5. 5. Critical Power: Circuit Protection in Health Care Facilities
  6. 6. 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
  7. 7. 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
  8. 8. Quick Thoughts on These Codes • NFPA 99, Health Care Facilities Code – Covers many more topics than electrical – Chapter 6 – Electrical Systems • – 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
  9. 9. 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
  10. 10. 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
  11. 11. 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
  12. 12. 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
  13. 13. 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
  14. 14. 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).
  15. 15. Patient Care Area (General or Critical Care) • Emergency Circuits (Life Safety & Critical) 1. Require redundant grounding – NEC 517.13 • Grounding conductor and metal conduit 2. 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
  16. 16. Patient Care Area (General or Critical Care) • Normal or Equipment System Circuits 1. Also require redundant grounding 2. 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
  17. 17. 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
  18. 18. 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
  19. 19. Hospital Grade Flexible Cable • A “cross” between AC and MC Cable – Has a grounding conductor (like MC) – Sheath is ground rated (like AC)
  20. 20. In a Non-Patient Care Area • Emergency Circuits 1. Redundant grounding not required 2. Still require mechanical protection 3. Allows more flexibility of installation – but #2 still leads to metal conduit often • Normal Circuits 1. Redundant grounding not required 2. Mechanical protection not required 3. This allows much more flexibility of installation
  21. 21. Distribution Protection Short Circuit Protection Selective Coordination Arc Flash Protection
  22. 22. Short Circuit Protection • Input Data • Calculations • Equipment Ratings • Nameplates
  23. 23. 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 devices Results: Short Circuit Fault Available at locations throughout the distribution
  24. 24. 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!
  25. 25. Short Circuit Calculation Results Example BUS V 3-Phase Fault on Utility (A) 3-Phase Fault on Generators (A) Largest Available Fault AHU 2-1 480 9650.3 9754.2 9754 ATS CR1 480 44949.2 44494.5 44949 ATS EQ2 480 39695.3 43448.5 43449 CH2ORDPB 480 32965.1 33894.8 33895 CL2A 208 5598.2 5595.9 5598 LSH1 480 21621.5 21106.3 21622 NH3 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.
  26. 26. 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
  27. 27. 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
  28. 28. Short Circuit Ratings – What needs one? Switchboards Automatic Transfer Switches Panelboards Motor Controllers Electrical Disconnects Elevator Controllers Pump Starters Industrial Control Panels Adjustable Speed Drives
  29. 29. Selective Coordination • NEC Definition of Selective Coordination
  30. 30. Selective Coordination Goal 1. Protect other circuits by ensuring the breaker in trouble trips first 2. Protecting equipment and infrastructure a. Transformers b. Cables c. Motors d. Generators
  31. 31. 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
  32. 32. Selective Coordination Process Select Overcurrent Device Check Coordination Adjust Distribution
  33. 33. Selective Coordination Demonstration • Use Time-Current Curves to demonstrate Selective Coordination Current Time
  34. 34. Example Example 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.
  35. 35. 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
  36. 36. Selective Coordination 0.1s Debate For 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
  37. 37. 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
  38. 38. 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.
  39. 39. Learning Objective Summary • Applicable Codes • Feeder & Branch Circuit Protection • Redundant Grounding at Patient Locations • Short-Circuit Calculations • Selective Coordination • Arc Flash
  40. 40. Submitting Questions, Exit Survey and Archive Question? Type your question in the “Ask a Question” box on the Webcast Console and click “Send.” We will get to as many questions as we have time for. Questions that are for today’s presenters will be answered verbally during the Q&A session. Exit Survey: Please take a moment to answer a few questions on our exit survey that will pop up on your screen at the conclusion of the webcast. We use the answers to help make improvements to our webcast program. 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 home page
  41. 41. 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:
  42. 42. Thanks to Today’s Webcast Sponsors:
  43. 43. Critical Power: Circuit Protection in Health Care Facilities Sponsored by: