Anybody ever hear of a "Neutral Fault Test"?

[Fulthrotl]

appreciate any experience you may have on this subject....

The AHJ has decided to implement on a small commercial occupancy,
the "Neutral Fault Test"

the building is 30 years old. it is being brought up to current codes,
with special attention being given to Title 24 compliance.

The inspector has stated that the "neutral fault test" will be performed.
here is the drill, and logic behind it....

as the grounded conductor, and grounding conductor serve separate
functions, and should not be joined together in the field wiring, it should
be possible to lift the feeder neutral in a panel, and read no conductivity
between the neutral bus, and the ground bus. infinite resistance.

and that is what the inspector is going to watch me do. he will not
sign off the electrical permit without this test being performed to his
satisfaction.

anything other than infinite resistance will require the wiring of the
building to be corrected until this fault is cleared.

and, on the engineered drawings, where the city's stamp is affixed, it
is noted by the approving plan checker that "neutral fault test is to be
performed". so, it is sanctioned by the powers that be.

any of you guys have experience with this?

.... i have only found this "neutral fault test" performed in one locality...
and i've worked in a lot of places. thanks for any feedback you may have.

 

[ohm]

Every mobile home here is checked that way. The inspector sets his meter for conductivity (300 ohms or so beeps).

On an older home with a 3 wire range or dryer plug they need to be pulled before the inspector gets there. If any stray bare wires are touching a neutral you fail.

 

[LarryFine]

as the grounded conductor, and grounding conductor serve separate
functions, and should not be joined together in the field wiring, it should
be possible to lift the feeder neutral in a panel, and read no conductivity
between the neutral bus, and the ground bus. infinite resistance.

As long as you're talking about the premises side of the break, I agree. I've never thought of doing that, but I will next chance I get.

You do mean before the service is energized, of course.


I just thought of when this wouldn't work: when you have the old-style 3-wire feeder to a detached building. The service neutral is re-earthed.

 

[LarryFine]

On an older home with a 3 wire range or dryer plug they need to be pulled before the inspector gets there.

Why would that make any difference?

Unless the dryer had a metallic duct in contact with the chassis.

 

[brother]

if they want 'infinite' then i just get a 'low ohm' reading meter. like 10 ohms

 

[brian john]

Every main line service switch we test we lift the neutral ground bond and MEGGER, the neutral to ground.

COMMON TEST the GFP will not function adequately unless the downstream neural is free of connections to ground.

 

[Pullnwire]

appreciate any experience you may have on this subject....

The AHJ has decided to implement on a small commercial occupancy,
the "Neutral Fault Test"

the building is 30 years old. it is being brought up to current codes,
with special attention being given to Title 24 compliance.

The inspector has stated that the "neutral fault test" will be performed.
here is the drill, and logic behind it....

as the grounded conductor, and grounding conductor serve separate
functions, and should not be joined together in the field wiring, it should
be possible to lift the feeder neutral in a panel, and read no conductivity
between the neutral bus, and the ground bus. infinite resistance.

and that is what the inspector is going to watch me do. he will not
sign off the electrical permit without this test being performed to his
satisfaction.

anything other than infinite resistance will require the wiring of the
building to be corrected until this fault is cleared.

and, on the engineered drawings, where the city's stamp is affixed, it
is noted by the approving plan checker that "neutral fault test is to be
performed". so, it is sanctioned by the powers that be.

any of you guys have experience with this?

.... i have only found this "neutral fault test" performed in one locality...
and i've worked in a lot of places. thanks for any feedback you may have.

Let me guess, Huntington beach? Tell Kevin I say hello.....

 

[cowboyjwc]

We call it a "neutral clear test" here. It's basically the same thing they do when they are certifying a GFCI breaker.

I simply have them pull the neutral disconnect link and put a continuity tester across it. I don't suggest that you use a Fluke or one of the really sensitive ones, sometimes they will read the wire impeadence and you don't want that.

 

[cmanningjr]

I've seen it done here in Alabama as well. It's really not that big of a deal. I'd watch for things like dryers and stoves or anything that may be bonded to the neutral.

Bad thing is, in an old building, there's no telling where a bond could be.

 

[cowboyjwc]

One more thing, I'm more inclined to ask for it when there is a GFCI on the system.

 

[ohm]

Why would that make any difference?

Unless the dryer had a metallic duct in contact with the chassis.

Because the 120v timer, clock & light is connected from a line to ground.

 

[Fulthrotl]

I've seen it done here in Alabama as well. It's really not that big of a deal. I'd watch for things like dryers and stoves or anything that may be bonded to the neutral.

Bad thing is, in an old building, there's no telling where a bond could be.

yep. bad thing is.... this buildings 30 years old.... and, no surprise,
it failed the test..... later this week, i'll down the service and see which
white wires are ugly. some of it's steeltube, some is bx, some is ac cable,
most of it isn't gonna be fun snoodling thru to find the connection. some
has grounds pulled, some doesn't. typical.

yeah, in residences, the 220 volt oven that has been upgraded,
and there was no neutral, and they need 110v. for the 8 watts of
oven controls, and the neutral is tied to the ground..... the kiss of death
for this test.

however, i do have a magic bullet to find the ground and neutral tie...
at least, i think i do.... if it works, i'll post it here for bragging rights,
and to prove that i really am a legend in my own mind.

randy

 

[Nick]

I see your from Huntington Beach. As mentioned before they have been requiring this for years. Be prepared to do it on any job you do there. BTW, for some reason HID lighting can be the cause of a lot of frustration in trying to get a clear reading.

 

[peter d]

yeah, in residences, the 220 volt oven that has been upgraded,
and there was no neutral, and they need 110v. for the 8 watts of
oven controls, and the neutral is tied to the ground..... the kiss of death
for this test.

Gaaaaahh!!

 

[hillbilly1]

Because the 120v timer, clock & light is connected from a line to ground.

The drum motor is also 120.

 

[LarryFine]

Because the 120v timer, clock & light is connected from a line to ground.

But that wouldn't create a bond between the service neutral and EGC.

 

[LarryFine]

I'd watch for things like dryers and stoves or anything that may be bonded to the neutral.

That still doesn't create a connection between the supply neutral and the EGC.

If the appliance BC is a 3-wire cable, the combined neutral/EGC of the appliance will only be connected to the service neutral (preferred) OR the EGC, not both.

If the applinace BC is a 4-wire, the appliance's neutral/EGC bond should be broken, again not creating a neutral/EGC bond for the service itself.

 

[LarryFine]

yeah, in residences, the 220 volt oven that has been upgraded,
and there was no neutral, and they need 110v. for the 8 watts of
oven controls, and the neutral is tied to the ground..... the kiss of death
for this test.

Actually, there was 'no EGC,' not 'no neutral.' The old 3-wire allowance was a case of the neutral being permitted to do EGC duty, not the other way around.

The neutral/EGC bond at the appliance only occurs when both do not run to the appliance; otherwise, the two conductors would effectively be run in parallel.

 

[ohm]

Actually, there was 'no EGC,' not 'no neutral.' The old 3-wire allowance was a case of the neutral being permitted to do EGC duty, not the other way around.

The neutral/EGC bond at the appliance only occurs when both do not run to the appliance; otherwise, the two conductors would effectively be run in parallel.

Larry your absolutely correct, never really paid attention when they did their little check, except when it beeped!

Maybe they throw in a line to ground check free of charge.

Or, if the 3 wire dryer has the neutral connected to the can AND the green wire they provide is connected to the cold water pipe.

Unplugging the range & dryer always worked but I didn't think it all through.

 

[LarryFine]

Unplugging the range & dryer always worked but I didn't think it all through.

If that's the case, then the neutral connection to ground must be occurring outside the BC wiring, such as the range cabinet making contact with a grounded surface, or the dryer cabinet touching the washer, or as I said before, a metallic exhaust duct grounded somewhere.