Grounding equipment in an enclosure on a pole

[shandupe]

I work for a low voltage contractor and we have a pole with ufer ground(recently installed for cameras only) that we're mounting an enclosure to. We are having 120VAC brought from a nearby building lighting panel into the enclosure to power a camera and fiber module in the enclosure. The customer's facilities mgr asked that an SPD be installed at the 120VAC in the enclosure to help divert any lightning events at the pole from tracking back to the building. Normally I would take the 120VAC and connect it to the input of the SPD and take the output from that into a breaker/terminal strip for our equipment. However, I believe the pole/earth ground should be used for the SPD in this situation. This is where I get fuzzy on the issue. The electrical ground from the building is needed for our equipment reference. If I use the earth ground fro the SPD I imagine I also need to bond the enclosure with that ground. What do I now do with the electrical ground? (* The pole is not part of a single point ground system)

I've brought the issue up to electricians and electrical engineers with a different answer each time.. Any clarity you can bring to this situation would be greatly appreciated.

Thanks,
Shannon

 

[david luchini]

I believe 250.32(B)(1) would apply to your situation. Your equipment grounding conductor run with the supply conductors should be connected to the grounding electrode at the pole, creating a single ground point.

 

[ActionDave]

....I've brought the issue up to electricians and electrical engineers with a different answer each time.. Any clarity you can bring to this situation would be greatly appreciated.

Mr. Oreily/Luchini is correct. Not a lot a mystery to overcome just a lot of misinformed individuals.

 

[shandupe]

RE

RE

Excellent.. It was actually my original plan until other "theories" were tossed about..
Thank you for you clarification..

 

[zbang]

The electrical ground from the building is needed for our equipment reference.

Be careful there, it sounds like there are LV signals from pole to building, so you'll need surge/transient protection at both ends of the signal cables, especially if they're overhead. This is where optical isolators are your friend.