Industry Forums > Wireless Service Providers > Grounding question

Grounding question

do they not have a halo around the roof? most do.

if not, then you need to run it back to teh master ground wherever that may be. if the tenant has a subpanel in their space they may have a grounding bus you cna go to, but not necessarily.
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Lack of Preparation on YOUR Part does NOT Constitute an Emergency on Mine!

reply to battleop

There isn't a grounding ring on the building. There is no exposed metal to ground to with out running several hundred feet. The closest thing is the building's frame but everyone seems to frown on taking a ground into a building like that.

The only thing up there are HVAC units. If we look for a ground near the unit they want us to become responsible for the unit. I.E. anything that can be blamed on a lighting strike can and will be.

I think that you need to hire a licensed electrician. This is one of those times where it is better to have someone you can "pass the buck" to.

Too bad there isn't someone to "Pass the cost to" . I've been on top of 5 or 6 Wal-Marts in our area doing various site surveys and none of them have a halo.

reply to davidg
A halo or any other grounding on a roof in this area is very, very rare. Unless the building is more than 6 or 7 stories it's just something we don't see.

reply to davidg
Is there a distance limit on running a ground? This is a newer Wal-Mart Super center and it's a very long run to the service entrance.

"subpanel in their space they may have a grounding bus you cna go to"

I thought that was a No No. If I can take it to the interior of the building I can just connect to the building's frame.

Take a look at NFPA 780. I think it may be allowable to ground to the frame. It is available for viewing on the NFPA website.

If that is the case this isn't an issue. There are a couple of nearby PVC conduits in the area that were were never used.

PVC conduit with weatherhead would be ideal to get into the building so you can snag structural steel with a beam clamp.

I'm preparing for a job where I am doing just that.

#2 stranded off the non-pen mount, through the weatherhead and conduit to inside the building. In my case the weatherhead and conduit is metal, so I am bonding the #2 outside the building before it goes into the weatherhead, and then inside the building where it comes out of the weatherhead. This will ensure that the weatherhead does not become a choke during an event.
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"No job is so important, and no service is so urgent that we cannot take the time to perform our work safely."
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Yup I am aware of the flashover risk.

The risk of NOT grounding the roof mount is higher than grounding it. Plus I was not planning on laying the copper on the roof.

reply to battleop

I am sure that will make the project unprofitable. I would rather walk away than spend thousands on an install that I can't recover.

You could explain to Wal-Mart that this building does not seem to have NFPA 780 compliant protection and any damage to struture and contents due to lightning storms may not be covered by their insurance.

You can add extra paragraph for hooking up antenna mast to standard commercial sytem spec ( such as
»www.lightning.org/documents/Long···tion.pdf ) and give it to the manager. Remember someone forgot to do this step in the original building contract!

None of the buildings in this area have any kind of real grounding system on the roof. In the last 3 or 4 years there is only one or two large buildings that I recall that have a decent grounding system on the roof.

reply to battleop
Don't waste time looking for a "halo." It's a violation of the NEC (and for good reason!) to ground an antenna to any lightning protection system. You need to bond to the electrical service ground, and only to that.

Interesting -- have you ever read NFPA 780? It says the opposite. It is the standard for Lightning Protection Systems!

reply to SuperWISP
Yup. On a rooftop with an installed LPS you are to bond to that.