8/13/2019 hospital raceway.docx

1/2

last two exceptions, involving the use of rigid nonmetallic conduit (RNC), need clarification.The text almost seems to imply that neither the feeder conductors nor the branch circuitconductors can be installed in nonmetallic conduit where the branch circuits supply power tofixed electrical equipment or receptacles in a patient care area. Branch circuits supplying fixedelectrical equipment or receptacles in a patient care area must have redundant grounding,which cannot be accomplished using nonmetallic conduit. This restrictive text only applies to

the branch circuit for a patient care area in accordance with Section 517.13 and not to thefeeder.- See more at:http://www.ecmag.com/section/systems/nonmetallic-conduit-essential-hospital-

systems#sthash.TItJqwv7.dpuf

Remember, nonmetallic raceways cannot be used for branch circuits that supply patient care areas since

Section 517.13 requires a metal raceway and a separate insulated equipment-grounding conductor as a

redundant path for grounding. - See more at:http://www.ecmag.com/section/codes-standards/emergency-

protection-stat#sthash.EvBBACf9.dpuf

All branch circuits shall be installed in metal conduit suitable for redundant ground return

path.

Click To View Full Size

Nonmetallic Conduit for Essential Hospital

Systems

Published:August 2004

ByMark C. Ode

The five exceptions to providing nonflexible metal racewaysProviding alternate power for essential electrical circuits in a hospital is extremely importantduring loss of normal power. Providing protection from damage will provide additional

assurance of the continuity of power to circuits that are vital to the protection of life and safetyin a hospital.An essential electrical system is defined in the National Electrical Codeas a system ofalternate sources of power and all connected distribution systems and ancillary equipment,designed to ensure continuity of power to designated areas and functions of a healthcarefacility during disruption of normal power sources, and designed to minimize disruption withinthe internal wiring system.The essential electrical system for a hospital is made up of two separate systems capable ofsupplying a limited amount of lighting and power for the operation of equipment necessary forthe life safety of patients and for the effective operation of the hospital. The two separateessential systems are the equipment system and the emergency system.The equipment system supplies major electrical equipment for basic hospital operation andpower for electrical equipment for patient care. Some examples of equipment connected to

the essential equipment system are central suction or compressor air systems serving

http://www.ecmag.com/section/systems/nonmetallic-conduit-essential-hospital-systems#sthash.TItJqwv7.dpufhttp://www.ecmag.com/section/systems/nonmetallic-conduit-essential-hospital-systems#sthash.TItJqwv7.dpufhttp://www.ecmag.com/section/systems/nonmetallic-conduit-essential-hospital-systems#sthash.TItJqwv7.dpufhttp://www.ecmag.com/section/systems/nonmetallic-conduit-essential-hospital-systems#sthash.TItJqwv7.dpufhttp://www.ecmag.com/section/codes-standards/emergency-protection-stat#sthash.EvBBACf9.dpufhttp://www.ecmag.com/section/codes-standards/emergency-protection-stat#sthash.EvBBACf9.dpufhttp://www.ecmag.com/section/codes-standards/emergency-protection-stat#sthash.EvBBACf9.dpufhttp://www.ecmag.com/section/codes-standards/emergency-protection-stat#sthash.EvBBACf9.dpufhttp://www.ecmag.com/node/111298http://www.ecmag.com/node/111298http://www.ecmag.com/node/111298http://www.ecmag.com/contributing-authors/mark-c-odehttp://www.ecmag.com/contributing-authors/mark-c-odehttp://www.ecmag.com/contributing-authors/mark-c-odehttp://www.ecmag.com/contributing-authors/mark-c-odehttp://www.ecmag.com/node/111298http://www.ecmag.com/section/codes-standards/emergency-protection-stat#sthash.EvBBACf9.dpufhttp://www.ecmag.com/section/codes-standards/emergency-protection-stat#sthash.EvBBACf9.dpufhttp://www.ecmag.com/section/systems/nonmetallic-conduit-essential-hospital-systems#sthash.TItJqwv7.dpufhttp://www.ecmag.com/section/systems/nonmetallic-conduit-essential-hospital-systems#sthash.TItJqwv7.dpuf

8/13/2019 hospital raceway.docx

2/2

medical and surgical functions, smoke and stair-pressurization systems, and heating orcooling equipment for general or critical care patient areas.The emergency system has been divided into the life safety branch and the critical branch.The life-safety branch supplies power to electrical circuits that are necessary for illuminationfor corridors, passageways, stairways and landings at exits from the building. Fire alarmsystems and medical gas alarms are connected to the life-safety branch, as well as hospital

communications systems used for instructions during emergency conditions. Cab lighting andthe control, communications and signaling systems for elevators can be connected to the life-safety branch since one or more elevators may be used for patient evacuation during a fire orother catastrophe. Automatic electric doors have been added to this list of life-safety-branchequipment, since having power to the automatic doors will help in evacuation.The critical branch supplies power for task illumination, selected receptacles, fixed electricequipment and special power circuits serving patient care areas, as well as specialenvironments and functions related to patient care in the hospital. Operating rooms,postoperative rooms, medication preparation areas, pharmacy dispensing areas and generaland critical care patient bed locations are just a few locations within a hospital withemergency circuits supplying receptacles and task lighting.Section 517.30(C)(3) requires the wiring of both the life-safety and the critical branch of theemergency system to be mechanically protected from potential damage by installing the

emergency feeder and branch circuits with mineral-insulated, metal-sheathed cable (Type MIcable) or in nonflexible metal raceways. Electrical metallic tubing (EMT), rigid metal conduit(RMC) and intermediate metal conduit (IMC) are a few examples of the more common metalraceways used for protection of these most important power systems.There are five exceptions to this general rule of providing nonflexible metal raceways forphysical protection of these circuits. Where the cords are supplying emergency power toappliances or other electrical utilization equipment, flexible cords are not required to beinstalled in raceways. Any signaling systems or communications systems powered by theemergency system but supplied by the secondary of a transformer does not require araceway, unless required by Chapters 7 or 8 of the NEC. Flexible metal raceways and flexiblecable assemblies can also be used in listed prefabricated medical headwalls at patient beds,in listed office furnishings or where necessary for flexible connection to equipment. Alwaysask the inspector for special permission in writing to use a flexible metal raceway or cable

assembly before connecting to electrical equipment since a judgment call will be necessaryfor a final determination of flexibility. The last two exceptions, involving the use of rigid nonmetallic conduit (RNC), needclarification. The text almost seems to imply that neither the feeder conductors nor the branchcircuit conductors can be installed in nonmetallic conduit where the branch circuits supplypower to fixed electrical equipment or receptacles in a patient care area. Branch circuitssupplying fixed electrical equipment or receptacles in a patient care area must haveredundant grounding, which cannot be accomplished using nonmetallic conduit. Thisrestrictive text only applies to the branch circuit for a patient care area in accordance withSection 517.13 and not to the feeder.A change in the 2005 NECwill clarify that only the branch circuit supplying power to fixedelectrical equipment and receptacles must comply with the grounding redundancy in 517.13.Feeders can be installed in nonmetallic conduit if the restrictions in the two exceptions are

followed. ECODEis a staff engineering associate at Underwriters Laboratories Inc., in Research TrianglePark, N.C. He can be reached at 919.549.1726 or atmark.c.ode@us.ul.com.- See more at: http://www.ecmag.com/section/systems/nonmetallic-conduit-essential-hospital-

systems#sthash.meQzaaEv.dpuf

You must install all branch circuits so they have a ground path for fault current. This meansinstallation in a metal raceway system or a cable armor or sheath assembly-each of whichmust qualify as an effective ground-fault current path per 250.118. Examples of such araceway or cable are EMT or Armored Cable (Type AC cable). See Figure 517-1.

mailto:mark.c.ode@us.ul.commailto:mark.c.ode@us.ul.commailto:mark.c.ode@us.ul.commailto:mark.c.ode@us.ul.com