Need code referance ?

Status
Not open for further replies.
J

Jhr

Senior Member
Senerio: Detached residential garage fed undergroud about 50 feet,1" PVC # 6 thhn, single phase 120/240 with a # 10 equipment ground, feeders are protected with a 60 amp 2pole breaker, at 200amp main panel at main house. Need code referance that states this sub panel needs a main breaker and separate grounding electrode due to it been a detached building, sub panel has 8 breakers in it, this city is under 2002 code, I know its in there somewhere I just can't locate it and is this to be treated as a seprate service :confused: .
 
Re: Need code referance ?

250.32(A) requires the grounding electrode.

The panel does not need to have a main breaker. The fact that there is a breaker on the main panel keeps you from having to deal with the six disconnect rule.
 
Re: Need code referance ?

Originally posted by Jhr:. . . is this to be treated as a seprate service?
Click to expand...
It's not a service. You have a feeder providing power to a panel. Within that garage panel, the neutral and ground buses need to be separated from each other. The #10 equipment grounding conductor from the main panel serves as the means for bonding the equipment in the garage. But you should check out 250.32(B), as there may be another way to handle the equipment grounding conductor.
 
Re: Need code referance ?

i agree with charlie, but be prepared as there are those who will push that there is no common electrical path for requiring the ground. Does not seem too likely here that there would not be eventual, if not actual, parallel ground paths like phone, water, reinforced concrete walkway.

paul
 
Re: Need code referance ?

Reading into NEC 2002 250.32 (A) and (B) 1, why would I need a seprate ground rod, the equiptment ground shall be used for grounding or bonding. One more thing the subpanel main is what the question mostly was about, and I should have edited my original post but you guys type faster than me, this is a red tag that I received by my inspector, and I feel that he is right I just can't find the code refrance, I put a phone call in to him and as soon as he calls back I will post the code refrance. :confused:

[ October 28, 2005, 02:13 PM: Message edited by: Jhr ]
 
Re: Need code referance ?

jhr,
250.32(A) Grounding Electrode Building(s) or structure(s) supplied by feeder(s) or branch circuit(s) shall have a grounding electrode or grounding electrode system installed in accordance with 250.50. ...
Click to expand...
 
Re: Need code referance ?

But isn't the fact that there is a GE system established at the main service and the equipment ground is bonded at the main panel, the use of a seprate ground rod is not required.
 
Re: Need code referance ?

The ground rod serves a differnt purpose than the EGC.

The GEC is for surges and lightning that may hit this out building. The EGC is to clear a fault at the main panel that may occure at the outbuilding.

The following is from Mike Holts training material.

1113857820_2.jpg


(A) Grounding Electrode. To provide a path to earth for lightning, each building or structure must have its disconnecting means [225.31] grounded (earthed) to one of the following electrodes [250.50 and 250.52(A)]:

Underground metal water pipe [250.52(A)(1)]

Metal frame of the building or structure [250.52(A)(2)]

Concrete-encased steel [250.52(A)(3)]

Ground ring [250.52(A)(4)]


Author?s Comment: See Article 100 for the definitions of ?Building? and ?Structure.?
Where none of the above grounding electrodes are available at a building or structure, then one or more of the following must be used:
Ground rod [250.52(A)(5)]

Metal underground systems [250.52(A)(7)]
Author?s Comment: Grounding the building or structure disconnecting means to the earth:
? Is intended to limit elevated voltages on the metal parts from lightning [250.4(A)(1)]. Figure 250?81
? It doesn?t serve as a low-impedance fault-current path to clear ground faults. In fact, the Code prohibits the use of the earth as the sole return path since it?s such a poor conductor of current [250.4(A)(5) and 250.4(B)(4)].
? It doesn?t protect electrical or electronic equipment from lightning voltage transients.
Exception: A grounding electrode isn?t required where only one branch circuit serves the building or structure. For the purpose of this section, a multiwire branch circuit is considered to be a single branch circuit. Figure 250?82

(B) Bonding Requirements. To quickly clear a ground fault and remove dangerous voltage from metal parts, the building or structure disconnecting means must be grounded (bonded) to an effective ground-fault current path in accordance with (1) or (2) [250.4(A)(3)]. Figure 250?83

(1) Equipment Grounding (Bonding) Conductor. The building or structure disconnecting means can be bonded to an equipment grounding (bonding) conductor, as described in 250.118, installed with the feeder conductors. Figure 250?84

Roger
 
Re: Need code referance ?

A grounding electrode is ALWAYS required at the separate building UNLESS the building is supplied by "only one branch circuit". Since a ground wire was installed with your feeder you will keep the grounds and neutrals separate in the garage (like it was a sub-panel). See 250.32(A) and the exception that follows.

Also a disconnect for the feeder is required "nearest the point of entrance of the conductors". The disconnect may consist of "not more than...six circuit breakers" Since you have an 8-circuit panel in the garage a main disconnect will be required. See 225.31, 225.32, and 225.33(A).
 
Re: Need code referance ?

Thanks Roger, but the in the picture shown the GEC looks like a ground rod, that is not listed on the list of sutible GECs in the picture, so now what, but what about the sub-panel in the garage needing a main breaker?

[ October 28, 2005, 03:21 PM: Message edited by: Jhr ]
 
Re: Need code referance ?

There is no code section that would require it. So you can do without it.
 
Re: Need code referance ?

Don and Sparky, I am seeing this differently.

225.32 says the building must have a disconnecting means. I did forget that part, so thank you Sparky for pointing that out. But it does not require a main breaker. Specifically it does not require the overcurrent protection that would come with a breaker. The easiest way to satisfy 225.32 is to use a main breaker in the panel. But you can also do it with an unfused disconnect switch just outside the garage.

225.33(A) would not come into play here. That is because it first refers you back to 225.30. That article says the garage can only have one feeder, unless permitted by the next five paragraphs. This garage has only one feeder. So the "not more than six" rule in 225.32(A) does not apply.
 
Re: Need code referance ?

Originally posted by Jhr:
Thanks Roger, but the in the picture shown the GEC looks like a ground rod, that is not listed on the list of sutible GECs in the picture, so now what,
Click to expand...
Jhr, it's kind of hidden in the list, look at the following exerpt from my post.

Author?s Comment: See Article 100 for the definitions of ?Building? and ?Structure.?
Where none of the above grounding electrodes are available at a building or structure, then one or more of the following must be used:
Ground rod [250.52(A)(5)]

Roger
 
Re: Need code referance ?

:eek: I thank you again Roger, I tell you these mono contact lenses are kinda wierd, got to look closer next time.
 
Re: Need code referance ?

I am a bit curious about the GE requirement for remote structures.

The code says something about it being required if more than one circuit is supplied.

I can't imagine anyone supplying more than one branch circuit out to the building. It might be a 100A circuit, but it is just one circuit so why is a GE ever required?
 
Re: Need code referance ?

Bob,
If the circuit is 100A, then it feeds OCPDs and is a feeder, not a branch circuit. The exception only applies to single branch circuits.
Don
 
Re: Need code referance ?

Ok, inspector called back Code reference NEC 2002 225.31,225.32,225.33,225.34, as I read 225.31 it seems to me that if a electrician was to run a 110volt circuit to a detached garage the electrician would be required to install a diconnecting means, but is this fused, nonfused or circuit breaker, your thoughts :confused: .
 
Status
Not open for further replies.
Top