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Neutral Fault Test #78363 09/11/01 07:08 AM
Joined: Dec 2000
Posts: 4,283
electure Offline OP
Member
In one of our municipalities, city code requires that a torque test be performed in front of the inspector (all panel and EXO terminations). OK, no biggy.

The same city requires a neutral to ground fault test. The building ground is disconnected from the neutral connection, and a test for continuity from load neutral to ground is performed. Kind of a pain in the ***, but it seems like a good idea.

Anybody else ever run into this? It's a first for me.

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Re: Neutral Fault Test #78364 09/11/01 07:27 AM
Joined: Oct 2000
Posts: 5,389
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sparky Offline
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??what is, or how is it tested?, i'm drawin' a blank here Scott......
[Linked Image]

Re: Neutral Fault Test #78365 09/11/01 07:47 AM
Joined: Mar 2001
Posts: 2,056
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Redsy Offline
Member
EXO=Disconnect?

Re: Neutral Fault Test #78366 09/11/01 08:07 AM
Joined: Aug 2001
Posts: 599
N
Nick Offline
Member
This wouldn't be Huntington Beach would it?!

Re: Neutral Fault Test #78367 09/12/01 08:04 AM
Joined: Dec 2000
Posts: 4,283
electure Offline OP
Member
Nick,
Right-ee-o, Surf City USA. Is this the only place where this is done? I'll add some more of their oddities for the other guys.
1.Appliances hardwired (GD, DW, etc). Disco means mounted where you'd normally put your recp.
2.PVC outdoors(or EMT, GRC painted with $60 per gallon marine paint) Go down the street a couple of blocks to Newport Beach, and they'll lynch you for using PVC on the roof.
3. 2x4 fluorescents in T-bar, 4 support wires to structure, 4 screws to grid. Downlights in T-bar 2 wires to structure, 4 screws.

Steve,
The process is to remove the grounding connection from the service neutral (I had a hot service, so was allowed to remove the neutral feeder conductors from their lugs in the panels, on a resi service, you take all the branch circuit neuts off and test them individually)
A continuity check is then taken from the neutral bar (or branch circ cond) to ground. You shouldn't have continuity. If you do, there is a fault someplace (screw through cable, etc). It would show up on an ungrounded conductor by a tripped C/B, but on a neutral, would never be found without this test. Seems like a real good idea to me.
I just have never heard of it elsewhere
(HB once had an inspector that thought "outside the box")

Re: Neutral Fault Test #78368 09/12/01 04:17 PM
Joined: Aug 2001
Posts: 7,520
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pauluk Offline
Member
I hadn't really thought about this before, but with your common neutral/ground busbar, I guess to find a short on a branch circuit you would have to test before both are connected to the bar.

In the U.K., we always have separate neutral and ground busbars, even in places where PME is used and the ground is bonded to the incoming neutral.

It's standard practice on a new installation to do two final megger tests:

1. All switches closed, bulbs removed, appliances unplugged etc. Test between hot & neutral with all fuses in/breakers closed.

2. Temporarily strap hot to neutral and megger between them and the ground busbar. It's also acceptable to do two separate tests: hot to ground & neutral to ground.

We don't even need to disconnect any main cables for these tests on domestic work, because our main switches are D.P. and open the neutral as well.

Re: Neutral Fault Test #78369 09/12/01 10:47 PM
Joined: Aug 2001
Posts: 599
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Nick Offline
Member
Quote
Originally posted by electure:
Nick,
Right-ee-o, Surf City USA. Is this the only place where this is done?

This is the only place I know of. I have never worked there but have heard all the complaining of co-workers that have. We do a lot of work there especially at Bowing. I think the neutral to ground test is a good idea. They do get a little carried away sometimes. One example: Parallel conductors. My superintendent was called by a Huntington Beach inspector because the CONDUITSwere not the same length. They knew the city was very particular about having the conductors exactly the same length(absolutely no variance) so they laid them on the floor, cut them EXACTLY the same length and then installed them without cutting them. The inspector would not pass the installation because the conduits were different lengths.

Re: Neutral Fault Test #78370 09/13/01 02:31 AM
Joined: Oct 2000
Posts: 2,721
Scott35 Online Happy
Broom Pusher and
Member
I also had the test done in Huntington Beach, along with a few other areas. John Childress from Simi Valley DBS is one that prefers this test.
It's a great idea to check it after the other trades have finished, just to make sure there's no re-grounded grounded conductors! [what a redundant statement [Linked Image]].
Not only that, but the "Neutral Disconnect Link" which service type switch gear has, gets to be used finally!

One other thing about Huntington Beach was penetration of the methane barrier under concrete slabs. I guess that there's an increasing amount of methane gas being pushed inland from the ocean. There's sure a lot of oil pumps in that area!!!

We saw cutted the existing slab to install floor boxes and stubs for teller line [bank branch project] and the Building Department was very concerned with us penetrating the methane barrier.

FYI: The SCE feeder conduits, along with the Telco riser duct to the MPOE were sealed like a gas station's conduits would be. Very rarely see that done!

Scott [electure],
We had to paint the heck out of any underground/underfloor ducts, conduits and boxes too! Once again, the methane situation must be the reason for this.
The Fire Sprinkler's feed [from street to the PIV inside building] was also required to be painted this way.
Wonder if the Landscapers' had to treat their irrigation lines??? [Linked Image] - It's possible! I could see methane being able to penetrate the PVC, then enter the irrigation lines and concentrate.

There's a few other AHJ's that want Disposals, Dishwashers, and the like to be hardwired [flex whips]. City / County of LA is one, and I think that Azusa does too. Seems that San Diego is another.

Scott SET


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
Re: Neutral Fault Test #78371 09/13/01 09:45 PM
Joined: Jun 2001
Posts: 7
S
sparkie Offline
Junior Member
I had a Calif State Mobile Home inspector do this on a mobile I replaced the subpanel in. It showed continuity between the N & G. On further investigation the water heater had the N & G tied together.

Re: Neutral Fault Test #78372 09/14/01 06:41 PM
Joined: Oct 2000
Posts: 5,389
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sparky Offline
Member
!!DING !! okay i got it, thanks
[Linked Image]
come to think of it, not a bad idea for any power quailty concerns either....


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