Grounding or bonding exterior metal walls

[nerspellsner]

I am wiring a horse barn with a indoor riding ring. It is about 130 feet by 180 feet. All of the framing is wood. The roof and and exterior walls are metal. I can not find anything in the NEC about grounding the metal exterior roof and wall panels. Do I have to ground or bond the metal? If so, am I grounding or bonding the metal? At how many points do I install a lug to attatch the grounding or bonding conductor? Thanks.

 

[infinity]

Re: Grounding or bonding exterior metal walls

The exterior metal skin of a building is not required to be bonded. Here is what 250.140(C) has to say:

250.140(C) Structural Metal. Exposed structural metal that is interconnected to form a metal building frame and is not intentionally grounded and is likely to become energized shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or the one or more grounding electrodes used. The bonding jumper(s) shall be sized in accordance with Table 250.66 and installed in accordance with 250.64(A), (B), and (E). The points of attachment of the bonding jumper(s) shall be accessible.