230.29 Supports over Buildings.

Metal support structures used for service conductors over a roof must be bonded.
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Metal support structures used for service conductors over a roof must be bonded.

Code Change Summary: Additional code language now requires bonding of metal supports holding up service conductors above a roof.

In most cases, overhead service conductors are connected to the utility pole at one end, and to the service mast for the building served at the other end. They are normally pulled tight enough to ensure that they maintain the minimum required height distance above the rooftop.

In rare cases, it may take an additional support, installed above a roof, to make sure that the minimum height required above the rooftop can be achieved.

New language in the 2017 NEC® will require bonding of this additional support if the support is made of metal. The bonding must be accomplished by means of a bonding jumper and listed connector to the grounded overhead service conductor.

Below is a preview of Article 230. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2017 NEC® edition of NFPA 70.

2014 Code Language:

230.29 Supports over Buildings. Service conductors passing over a roof shall be securely supported by substantial structures. Where practicable, such supports shall be independent of the building.

2017 Code Language:

230.29 Supports over Buildings. Service conductors passing over a roof shall be securely supported by substantial structures. For a grounded system, where the substantial structure is metal, it shall be bonded by means of a bonding jumper and listed connector to the grounded overhead service conductor. Where practicable, such supports shall be independent of the building.

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230.29 Supports over Buildings.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Which of the following is required when a structure is used above a rooftop to support overhead service conductors?

A: A metal support structure must be bonded by means of a bonding jumper and listed connector to the grounded overhead service conductor.
B: A plastic support pole must be bonded by means of a main bonding jumper and connector to the grounded overhead service conductor.
C: It CANNOT be independent of the building.
D: It CANNOT be bonded to the grounded overhead service conductor.
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