Metal-Clad Healthcare

By Michael Johnston | Jan 15, 2015
Code Comments January 2015.jpg




A reader wrote in that an inspector had turned down one of his projects, citing the installation was in violation of National Electrical Code (NEC) 517.13(A) and (B) because Type MC cable was installed in the patient-care areas. The reader asked about the requirements for equipment grounding conductors (EGCs) for branch circuits installed in patient-care areas and whether MC cable is an acceptable wiring method. The short answer is yes; certain types of MC cable are suitable for use as a wiring method in patient-care areas. Let’s take a more in-depth look at the Code rules.

The requirements for patient-care area branch-circuit equipment grounding conductors are provided in NEC sections 517.13(A) and (B). It is important to understand that both subdivisions (A) and (B) must be applied together to each branch circuit serving patient-care locations to meet the minimum requirements in this section. Two separate EGCs are required for these branch circuits. The idea is to have redundancy in the EGCs for branch circuits serving patient-care locations.

Section 517.13(A) specifies use of metallic wiring methods, such as metal raceways or cable assemblies, that are acceptable as EGCs in accordance with Section 250.118. This is one of two separate EGC paths required for branch circuits serving these locations. It is important to understand that this effective ground-fault current path in the form of a metallic wiring method is different in characteristics from the contained insulated copper conductor addressed in Section 517.13(B). So in review, Section 517.13(A) indicates that the metallic wiring method selected for the branch circuits in patient-care areas must qualify as an EGC in accordance with Section 250.118, and Section 517.13(B) requires an insulated copper EGC of the wire type with the branch-circuit conductors.

Code-compliant wiring methods for patient-care areas include metallic raceway systems or cables with a metallic armor or sheath that qualifies as an EGC in accordance with Section 250.118. Electrical metallic tubing (EMT) is often specified and installed as a branch-­circuit wiring method in patient-care areas. It is important to understand the types of conduit, tubing, cables and other wiring methods that qualify as EGCs inherently provide a path for ground-fault current through the raceway or metallic cable armor itself. Remember that the integrity of the EGC has everything to do with the workmanship providing suitable supporting and securing means as well as proper coupling and fitting installation. The rules addressing securing and supporting requirements for wiring methods approved for patient-care areas are typically located in the .30 section of each applicable wiring-method article. NECA-1, Standard for Good Workmanship in Electrical Construction, provides valuable information related to electrical installations that meet workmanship criteria.

Listed flexible metal conduit (FMC) is suitable as an EGC that meets the minimum requirements of the Code, but it does so under more restrictive conditions. Where listed FMC is installed for branch-circuit wiring in patient-care areas, it not only must meet the restrictive conditions provided in Section 250.118(5) but also must include an insulated copper EGC with the branch-circuit conductors. This insulated EGC, like all wire-type EGCs, must be no smaller than the sizes provided in Table 250.122 based on the rating of the overcurrent protective device for the branch circuit.

Listed FMC might be used in patient-care areas for facilitating flexible connections to equipment, such as medical head-wall assemblies in patient-care rooms of hospitals. When this wiring method is used in patient-care areas, the method for the branch circuit must meet the requirements of Section 250.118(5) as well as 517.13(A) and (B).

Listed liquidtight flexible metal conduit (LFMC) is, with restrictions, also suitable as an EGC. LFMC must meet the following conditions to be suitable for and function as an EGC for branch circuits serving patient-care locations: It must meet the restrictive conditions provided in Section 250.118(6), and it must include an insulated copper EGC with the branch-circuit conductors.

The question specifically seeks information about MC cables in patient-care areas. If metallic cable wiring methods are used for branch-circuit wiring in patient-care areas of healthcare facilities, the conductive armor must provide an effective ground-fault-current path and qualify as an EGC. There must also be an insulated copper EGC included in the cable assembly if used for a patient-care location. Some Type MC cable is suitable as an EGC, according to Section 250.118(10). Verify with the manufacturer that the type of MC cable installed on your project meets this requirement.

The UL Guide Information for Electrical Equipment under categories (PJAZ) and (PJOX) provides additional product information about Type MC cable assemblies and fittings.

About The Author

A man, Mike Johnston, in front of a gray background.

Michael Johnston

NECA Executive Director of Codes and Standards

JOHNSTON is NECA’s executive director of codes and standards. He is a member of the NEC Correlating Committee, NFPA Standards Council, IBEW, UL Electrical Council and NFPA’s Electrical Section. Reach him at [email protected]



Related Articles