Fencing Question

[dougjl]

I have a client that wishes to put a fence around a new 480V switch-gear that they are installing inside the plant. They want to do this to limit access to the equipment. I know that I need to meet the requirements of 110.26. My question is do I bond the fence to the building grounding system?
There does not appear to be any section of NEC code that I can find that discusses fencing for under 1000V. I have been poking around the internet and found a concern about the fence potentially becoming electrified if bonded to the ground system during a fault and being more dangerous than if left un-bonded. I'm not sure that makes sense as the whole ground system would see the fault so if that was true the building steel and every piece of equipment tied to the building steel would be electrified. I was thinking it would be a good idea to bond the fence as called out in 250.194. Even though that only pertains to sub-stations. Does anyone have any thoughts on this they would share?
Thanks

 

[waross]

Consider a buried, bare copper conductor parallel to the fence at a spacing that anyone touching the fence would be standing over the shallowly buried conductor.
At intervals thread a bare riser cable up through the chain link.
Use a suitable clamp to connect the riser cable to the top cross pipe and then separate the strands an connect a portion of the strands to each run of barbed wire.
This may be overkill.
I have grounded fences this way on substations up to 500 kV.