Is an additional bare copper bonding wire jumper required?

Michael Johnston
Posted by Michael Johnston September 16, 2008 Focus on the Code September/October 2008

Question

Article 250.92(A)(2) of NEC-2005 requires bonding between service enclosures.

I have a meter base can with the grounding electrode conductor connected to the neutral lug going to the grounding electrode. I have a single-phase three-wire service conductor system feeding from the meter can to the service-disconnect panel. The meter base can and the service-disconnect panel is connected by PVC pipe, not metal pipe.

As I see it, Article 250.92(B)(1) allows bonding equipment (the service-disconnect panel) to the grounded service conductor neutral bar (in the service-disconnect panel). Is this correct, or is an additional bare copper bonding wire jumper required to be connected from the service-disconnect panel neutral bar to the meter base can neutral bar? — R. P.

 

Answer

Your question deals with use of the grounded conductor for grounding and bonding on the supply side of the service disconnecting means. Your understanding is correct. The grounding conductor is permitted to be used for grounding and bonding on the supply side of the service disconnecting means. The grounded (neutral) conductor is required to be routed between enclosures and bonded to both, and this is common practice. The supporting NEC references are 250.92(B)(1) and 250.142(A)(1).

An additional equipment bonding jumper between the meter socket enclosure and the service disconnecting means enclosure is not required for bonding the enclosures together based on the information provided in your question.

Note that on the load side of the service, disconnecting means (service disconnecting means overcurrent device), separation between the grounded (neutral) conductor is required in accordance with 250.24(A)(5). The grounding electrode conductor connection to the grounding electrode is permitted to be made in either the meter socket enclosure or the service disconnecting means enclosure in accordance with 250.24(A)(1).

Note that some utilities do not permit this connection in the meter socket enclosure by local regulations because of customer accessibility issues. I hope this helps answer your question. — Michael J. Johnston, CMP-5

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Michael Johnston
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Michael Johnston is NECA’s executive director of standards and safety. Prior to his position with NECA, Mike was director of education codes and standards for IAEI. Mike holds a BS in Business Management from the University of Phoenix. Mike is the chairman of the NEC Correlating Committee. He served on NEC CMP-5 in the 2002, 2005, and chair of CMP-5 representing NECA for the 2011 NEC cycle. Among his responsibilities for managing the codes, standards, and safety functions for NECA, Mike is secretary of the NECA Codes and Standards Committee. Johnston is a member of the IBEW and is an active member of ANSI, IAEI, NFPA, SES, ASSE, ANSI-EVSP and ANSI-ESSCC, and the UL Electrical Council, the National Safety Council and vice chair of the NFPA Electrical Section.