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1793

1793

Senior Member
Location
Louisville, Kentucky
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Inspector
Looked at a job this morning where the customer wants to install receptacles for his Ham Radio equipment. He is demanding an ?Isolated Ground? from a ?Ground Rod? driven by this part of the house and run directly to his equipment.

I would like to know what section of Article 250 I should study to find out if this is a violation or the correct thing to do. Now I know I?m not the smartest person in the world but my gut tells me this is a violation and it is not necessary.

I would be running a dedicated 20 amp circuit,(NM-B) to his Radio Room. I could install an Isolated Ground Receptacle but again from what I think I know it is not necessary.

I don?t know how to reply to these people who ?Know so much.?

As always, thanks in advance and I look forward to your input.
 
It is compliant to connect a ground rod to the equipment grounding conductor—see 250.54 for the specifics—but this path to ground cannot be the only ground fault path. In other words, run the circuit to the desired location, with an EGC, then bond the ground rod to the EGC and thus the receptacle(s). This still meets the defintion of an isolated ground provided no other path is available for ground fault current to the GES/GC bond.
 
I agree with Smart. You cannot have an isolated ground rod and use it as an EGC. This EGC will never clear a ground fault. All electrodes must be connected together
 
Smart $ said:
It is compliant to connect a ground rod to the equipment grounding conductor?see 250.54 for the specifics?but this path to ground cannot be the only ground fault path. In other words, run the circuit to the desired location, with an EGC, then bond the ground rod to the EGC and thus the receptacle(s). This still meets the defintion of an isolated ground provided no other path is available for ground fault current to the GES/GC bond.
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I agree, my thought is what additional help the additional ground rod will this bring to the table?
 
1793 said:
I agree, my thought is what additional help the additional ground rod will this bring to the table?
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None.

Roger
 
roger said:
None.

Roger
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My understanding exactly. When folks throw around; "from my days of electrical engineering in collage we have to ..." it just sends me over the top. I don't have that same educational background so I can't defend myself, or at least I don't feel I can.
 
1793 said:
My understanding exactly. When folks throw around; "from my days of electrical engineering in collage we have to ..." it just sends me over the top. I don't have that same educational background so I can't defend myself, or at least I don't feel I can.
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The detail I'm curious about is whether his antenna mast and lead-in are properly grounded. I'm of the impression this guy is concerned about lightning induced currents flowing through his gear.
 
What if the receptacle itself was fed through an isolation transformer, creating a new SDS? Is there a way he could not have to bond the new electrode system to the house's?
 
1793 said:
He is demanding an ?Isolated Ground? from a ?Ground Rod? driven by this part of the house and run directly to his equipment.


I would be running a dedicated 20 amp circuit,(NM-B) to his Radio Room. I could install an Isolated Ground Receptacle but again from what I think I know it is not necessary.


I don?t know how to reply to these people who ?Know so much.?

you could offer to install an additional ground rod (maybe near the antenna lead in so it could be bonded to it) and explain that it legally must be bonded to the rest of the grounding sytem.

Also, if you are running a dedicated circuit, it basically is an isolated ground system, as there will be no other grounds connected till it gets to the pbrd.
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The advantage of this type of installation is if there is a lighting strike in the vicinity of the new electrode the current path can be through the electrode through the radio to the main electrode at the service frying his equipment and making his wife and neighbors some happy campers.
 
RayS said:
Also, if you are running a dedicated circuit, it basically is an isolated ground system, as there will be no other grounds connected till it gets to the pbrd.
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Yes, I agree that qualifies as the proper IG installation method. I believe the OP's customer wants a receptacle bonded only to an independent rod.

I asked above if using a 1:1 isolation-transformer-derived SDS would permit the use of an independent grounding-electrode system for its secondary circuit.
 
Iso transformer or not the NEC requires the antenna grounded / bonded to the premise electrical system 810.15 / 810.21

I believe the coax would bring the ground right back to the transceiver.





Edit 800 to 810
 
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Coax Isolation for lightning

Coax Isolation for lightning

I am not fully up to speed here, but regarding preventing a lightning strike from coming to equipment on the antenna coax, I believe there is a type of lightning connection block with a separate ground path that allegedly "takes" the hit and sends it to ground. Saw it on many antenna websites. For what it's worth.

RLK
 
rkrieger said:
I am not fully up to speed here, but regarding preventing a lightning strike from coming to equipment on the antenna coax, I believe there is a type of lightning connection block with a separate ground path that allegedly "takes" the hit and sends it to ground.
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They're called 'lightning arrestors', and they'be been around since the earliest days of radio.
 
Convince him that you have to ground to the panel to meet code. Then install the extra rod even if it is worthless, let him be smart. Take the extra money with a smile on the way out. That's one thing I've learned on this forum, be a better salesman.
 
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