Grounding and Bonding - Questions and Answers

Mike, In the latest e-mail, there was a question concerning grounding of receptacles in patient care areas of health care facilities.

"Q5. Grounding Patient Care Areas 517.13(A)
Wiring in patient care areas must be provided with a ground path for fault current by the installation of the circuit conductors in a metal raceway system, or a cable armor or sheath assembly that qualifies as an equipment grounding return path in accordance with 250.118. Can flexible metal conduit or surface metal raceways be used for branch circuits in these areas?

A5. Flexible metal conduit in lengths not exceeding 6 ft can be use for branch circuit wiring in patient care areas of a health care facility, if the circuit conductors contained in the raceway are protected by overcurrent devices rated at 20 amperes or less. Surface metal raceways are also considered suitable for grounding unless there were some marking, UL information that would prohibit its use as a sole grounding path."

Please advise your readers that they must be careful when working within patient care areas.  The NEC requires that "emergency" circuits in the patient vicinity be protected by installation in a metal raceway

517.30(C)(3).   "517.30(C)(3) Mechanical Protection of the Emergency System. The wiring of the emergency system of a hospital shall be mechanically protected by installation in nonflexible metal raceways, or shall be wired with Type MI cable.

Exception No. 1:  Flexible power cords of appliances, or other utilization equipment, connected to the emergency system shall not be required to be enclosed in raceways.

Exception No. 2:  Secondary circuits of transformer-powered communications or signaling systems shall not be required to be enclosed in raceways unless otherwise specified by Chapters 7 or 8.

Exception No. 3:  Schedule 80 rigid nonmetallic conduit shall be permitted if the branch circuits do not serve patient care areas and it is not prohibited elsewhere in this Code.

Exception No. 4:  Where encased in not less than 50 mm (2 in.) of concrete, Schedule 40 rigid nonmetallic conduit or electrical nonmetallic tubing shall be permitted if the branch circuits do not serve patient care areas.

Exception No. 5:  Flexible metal raceways and cable assemblies shall be permitted to be used in listed prefabricated medical headwalls, listed office furnishings, or where necessary for flexible connection to equipment."

Therefore metal-sheathed cable assemblies or flexible metal conduit would not be permitted even though it might meet the provisions of 250.118.  It would be permissible to use these on the normal source receptacles in patient care areas but not on emergency source receptacles.

Be careful.
Robert S. Murphy, Engineering Supervisor
Brookhaven Memorial Hospital Medical Center
rmurphy@bmhmc.org

Mike Holt's Comment: If you have any comments or feedback, please let me know, Mike@MikeHolt.com.

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