Ground rod at resi condenser

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GG

Senior Member
Location
Ft.Worth, T.X.
I had an HVAC contractor friend call and ask if the ground rod driven at the condenser would pass inspection. I said nope. He said his brother in law the city inspector said it was ok. I told him the ground rod would never clear a fault and thats not its purpose anyway. He has a 40 amp / 240V / 2 wire circuit and I told him to run a #10 wire to the cold water pipe that is 10' away from the unit. What code sections can I have for him to show the inspector that will likely fail this.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
A ground rods purpose is not to clear faults. The resistance ion the rod would have to be quite low to even come close to tripping a 40 amp breaker. It would need to be less than 6 amps-- not realistic in most places.

Although grounding to the water pipe is better than nothing I don't believe that is legit either. 250.130 allows this for receptacles but nothing else that I know about.
 

GG

Senior Member
Location
Ft.Worth, T.X.
Thats not good news. I was busy and shot from the hip when my friend called. So can he run a ground wire directly to the panel from his cond disconnect or does the NEC say the circuit conductors have to be in the same raceway? He said the existing conduit is running under the house and there is no way he can get a 3rd wire in it. Its been a while since I watched Mr. Holts grouding tapes and have been away from the electrial for a while so Im a little rusty but I atleast knew the ground rod at the condenser was no good. How would you ground it? TY
 

cadpoint

Senior Member
Location
Durham, NC
Read down through all of 300.3, there is a lot of cross referencing to grounding and bonding in the 250's, while there is limited application of a bonding or grounding wire on the outside of "run" it is very specific and in most cases need to be the same raceway, to begin with but it is allowed under 300.2(1).

The Article 250.53 (2) can be used as a Supplemental Electrode with the water pipe, but that also has to continue on to the one of five requirements in the article. Or is that the gound back to a panel, continually?

The run to the ground rod should be removed, because your not running it back to meet one of the the five conditions of 250.53 (2)

BASED ON 2011 WHICH HAS NEW REQUIREMENTS in 250.53, IE of the Five requirements, ...
 
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GG

Senior Member
Location
Ft.Worth, T.X.
What is the conduit? PVC, emt????
Its rigid from the existing condenser to an outdoor disconnect that is fed directly from the meter. The disconnect and and condenser are about 30' apart but the rigid goes under the house and then pops out under the disco. I told him to use the rigid as his ground but he wants to cut the rigid off and run PVC up to his pullout disco and from there install a condenser whip made of carflex.
 

GG

Senior Member
Location
Ft.Worth, T.X.
He has an EGC, he must use it. He can throw in a ground rod for sport if he wants, but that doesn't relieve him from using an EGC.
So the #10 to the CWG is forbidden by the NEC? How would you gorund it if you cant get a ground conductor in the existing rigid conduit? I guess he cant cut the existing rigid loose from the condenser and land it at his new disco. He does not have a pipe threader. If it were me I would just run a new 40 amp circuit with romex and be done with it, but he said he bid the job and had no clue about the grouding part of the condenser.

I see old rigid conduit and FP discos I usually bid a new panel with a new cond circuit, but thats just me. He said he ran the #10 to the cold water pipe like I advised him.
 

Twoskinsoneman

Senior Member
Location
West Virginia, USA NEC: 2020
Occupation
Facility Senior Electrician
Its rigid from the existing condenser to an outdoor disconnect that is fed directly from the meter. The disconnect and and condenser are about 30' apart but the rigid goes under the house and then pops out under the disco. I told him to use the rigid as his ground but he wants to cut the rigid off and run PVC up to his pullout disco and from there install a condenser whip made of carflex.

30' with carflex from the disconnect to condenser?

Since he isn't going to run a wire convince him to use the rigid as the EGC. I don't know what he's got from the disco to the condenser now but the easiest IMHO is to use something that could be used as EGC (RMC, IMC, EMT whatever based on the situation) then whip it with LFMC. (at least 3/4 size)
250.118(6)
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
So the #10 to the CWG is forbidden by the NEC?
Yes.

250.130 Equipment Grounding Conductor Connections. Equipment grounding conductor connections at the source of separately derived systems shall be made in accordance with 250.30(A)(1). Equipment grounding conductor connections at service equipment shall be made as indicated in 250.130(A) or (B). For replacement of non?grounding-type receptacles with grounding-type receptacles and for branch circuit extensions only in existing installations that do not have an equipment grounding conductor in the branch circuit, connections shall be permitted as indicated in 250.130(C).

250.130(A) requires using the EGC.

...he said he bid the job and had no clue...
Yeah, I'll go along with that. I'm with you on the method. :happyyes:
 

GG

Senior Member
Location
Ft.Worth, T.X.
Ill tell him tommorow that he is going to have to maintain the continuity of the rigid conduit up to his new condenser disconnect, and remove the #10 wire going to the CW pipe. Unless he wants to install a new 40 amp circuit which I doubt he will do.
 

stew

Senior Member
Have him put an outdoor box on the end of his rigid with a threadless rigid connector. They are the type that is a compressiion stlye connector similar to a compression emt. That gives him the egc back to the panel. Then put a ground screw in the outdoor box and make the flex transition at this box and continue the ground in the flex. very clean way to do it and would be how I would continue this egc.
 

GG

Senior Member
Location
Ft.Worth, T.X.
Have him put an outdoor box on the end of his rigid with a threadless rigid connector. They are the type that is a compressiion stlye connector similar to a compression emt. That gives him the egc back to the panel. Then put a ground screw in the outdoor box and make the flex transition at this box and continue the ground in the flex. very clean way to do it and would be how I would continue this egc.
Nice idea. TY
 
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