Lighting gorund into ac?

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ephesus56ad

Member
Before anyone jumps on me for being a GC, this is a question that was asked of me by one of my customers. I'll just you the basics. The house is a stantard 200amp service. Service entrance and breaker pannel on north side ac on south about 80' away. It is a bonded system. The customer has a satilite dish on the roof right above the ac unit. The lighting groung is tied on to the unit. So the question is, If the dish took a direct strike, would it ground properly or would it first blow other items in the house? And if possible be kind enough to tell me why? And should the dish be grounded to it's own rod?
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dereckbc

dereckbc

Moderator
Staff member
Location
Plano, TX
Re: Lighting gorund into ac?

No the dish is not grounded properly. You can put it on its own ground rod if you bond it back to the service ground. You cannot just add a rod for the dish and leave it isolated from the service ground, if struck there would be equipment damage and possible injury.
 
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hurk27

Senior Member
Location
Portage, Indiana NEC: 2008
Re: Lighting gorund into ac?

ephesus56ad

The main point is to never entice a lightning strike to follow a path into a house to get to the grounding electrode of the service as it can jump off at any point along the way and cause great damage and/or a fire. this is why you must install a ground rod and from the outside of the house run at least a #6 to the main service electrode.
the best installation would be to locate the dish ether by the service and have the ground wire short as possible or install the dish off the house like on a pole and bring the lead-in coax to the service and bond it to the ground rod. this provides a path the service electrode without going through the house. If you only install a ground rod at the dish the lighting will run down the coax and enter the house to get to the neutral of the circuit feeding the sat receiver. the same thing applies to phones or any communication lead-in's

[ August 31, 2003, 01:27 AM: Message edited by: hurk27 ]
 
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ephesus56ad

Member
Re: Lighting gorund into ac?

hey guys, i have a couple of rods from temp poles, would it help if i offered the homeowner this? He has #6 coming off the the sat dish.

[ August 31, 2003, 03:20 AM: Message edited by: ephesus56ad ]
 
charlie

charlie

Senior Member
Location
Indianapolis
Re: Lighting gorund into ac?

Originally posted by ephesus56ad:
Hey guys, I have a couple of rods from temp poles, would it help if I offered the homeowner this? He has #6 coming off the sat dish.
Click to expand...
NO! As simple as this sounds, get your EC to do the work. The grounding electrodes must be bonded properly, with the proper conductors, run properly, and with clamps listed for the use.

Sure, this is easy work but, if done wrong, will smoke the TV, VCR, DVD player, etc. Don't let amateurs do a professional's work, it will cost more in the end. :)
 
dereckbc

dereckbc

Moderator
Staff member
Location
Plano, TX
Re: Lighting gorund into ac?

ephesus56ad, the point everyone here is trying to make is you can install as many ground rods as you wish. You can have one for each service such as CATV, AC service, Satellite, antenna tower, phone etc. But they all have to be bonded together (preferable under ground) to form a single electrode system.. If you fail to do this you would use earth as a conductor for a fault path. The earth is not capable of doing this. The result is extremely high voltages will develop between system during a fault condition that will damage equipment, create a fire hazard, and personal injury.

As a GC if you have any influence on initial construction you should encourage the designers to bring all services (gas, water, electric, phone, cable, antennas, etc) into the facility at one point. A window if you will. This allows for simplicity of bonding the services, offers the greatest amount of protection and operation flexibility. You can bring them in from all sides, but if you do this you would need a ground ring to bond all of them properly.

So I must agree with the members you should use a licensed professional who understands the risk and dangers (and is bonded & insured). I would hate to see you injure someone or damage property by trying to do it yourself . I think you know what the legal implications are. :(

Good Luck

Dereck
 
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