What To Do With The Neutral Line??

Warmsmeallup

When installing a 240v / 30a powered system that only requires a 2 wire (2 leads plus ground) and the electrcian ran a 3 wire and connected the neutral to the neutral bar in the main panel, what do you do with the neautral line? Do you just cap it off? What happens if you tie it to the ground?

JumboJack

Why would you even think to tie it to the ground?

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in texas with framing and cornish people will do it for 3.00 a foot. What do yall think about that? Just laber

thom

You asked 3 questions.

What happens with the neutral line? Nothing. put a wire nut on it though, if it's in conduit it should be removed.

Do you cap it off? yes.

What would happen if it was connected to the ground connection? Nothing would happen though the installation would be improper. You would be using a white wire for a ground, that's a violation and might confuse someone in the future.

Magnettica

Tying the neutral conductor to the equipment grounding conductor at any point other than at the main disconnect where it is required would create a parallel path to ground.

I believe this violates 250.4.

Celtic

250.6 Objectionable Current

...is the article.

You are right on the other comments

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thom

Magnetta, how is this physically/electrically different than using an insulated grounding conductor inside conduit? The fixture/receptacle would be connected to the insulated wire and it would be connected to the conduit through the fixture attachment strap being screwed to the box.

Celtic

The ONLY place a neutral/ground connection should be made is at the service.

IF the neutral should break, you just energized every piece of metal connected o the service...all the plumbing, gas lines, etc.

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thom

I understand the requirement for the separation of the ground and common. My original post did in fact point out that this is a violation. I was merely questioning the parallel paths comment made by Magnetta. How would two insulated wires be different than an insulated wire inside a conduit?

Celtic

The "ground" is not insulated....the wire *may* be [type MC, etc] or may not be [NM, AC]...either way, the grounding conductor is bonded to all metallic parts ~ which are exposed and not insulated [such as faucets at a sink, tub, etc]

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Magnettica

What?

I don't understand your question.

thom

Ok, I'll try this again.

My response to the OP said that it was improper to connect the common to the ground at the receptacle, it would be a violation of code, but nothing would "happen" (his question was, what would happen?). Magnetta responded that the connection would create two parallel grounds (it would) which would be a violation (it is).

My question related to the parallel grounds. In a circuit, run in emt, with an insulated (isolated) grounding conductor, why does this not constitute two parallel grounds (the emt being one, the insulated grounding conductor being the other). Why would that situation (the insulated grounding conductor inside the grounded emt) be different than the two insulated conductors (the ground and the common) being connected to the ground lug at the receptacle?

I understand that it's a code violation to do the latter and I fully support that. It's the parallel grounds that I'm confused about.

Magnettica

I guess because it would be added resistance for the fault current to return to it's source before clearing at the OCPD.

The only reason why guys run an additional equipment grounding conductor is in case that fault path opens which it sometimes does when working with EMT.

thom

Thanks.

Until your post, I never had a thought about this. About 15 years ago, in a major truck-stop remodel, the operator (the guy who owned the franchise) insisted we run isolated grounds to all the pc's and electronic equipment. His contention was that a common ground could/would screw with the data. Rather than argue, (he was paying for it) I just had the guys run the isolated grounds inside the emt. The parallel paths thing just never crossed my mind.

Celtic

No problem Thom.

The EMT and insulated groundING conductor are the same....a neutral is a grounED conductor. Both of which serve different purposes.

The grounded conductor is the return path for the circuit....it will open a circuit under various conditions such as over load, short circuit, etc.

The grounding conductor is also a return path, but it's function is different. It's purpose is to return current to the source over a low impedance path.

In the case of parallel paths, this distinction becomes blurred in the eyes of the OCPD. A person caught in a circuit where parallel paths exist will appear to the OCPD as nothing more than any other resistive load such as a toaster...and that is what the person may become: toast.


I have a power point presentation [PPT] about parallel paths...PM me your email address and I will send it on over [the explanation contained is vastly superior to mine].


BTW.... PPT offer is open to anyone interested

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Celtic

EMT is listed as an EGC [250.118] when installed properly.

How many times have we seen EMT runs with loose set screws....sections of pipe seperated [at couplings/connectors] ?


IMHO, it's cheap insurance to run the EGC as THHN [or similar] and not rely on the EMT as an EGC with the "unknowns" that inevitably happen after we leave the job site.

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Magnettica

250.118 is an interesting article. I'm doing these open book tests as I prepare for the exam and I had to refer to it the other day for flexible metallic conduit.

No chit, this is where I found the answer...

c. For metric designators 21 through 35 (trade sizes
3⁄4 through 11⁄4), the circuit conductors contained in
the conduit are protected by overcurrent devices
rated not more than 60 amperes and there is no
flexible metal conduit, flexible metallic tubing, or
liquidtight flexible metal conduit in trade sizes
metric designators 12 through 16 (trade sizes 3⁄8
through 1⁄2) in the grounding path.

Celtic

Check out (E) for the "Oops" factor

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jrclen

This is pretty common Thom. And it is not a problem. Actually the problem is not parallel grounds, it is parallel neutrals. We don't want current flowing on the ground. And it would if we bonded the neutral to ground downstream from the main service disconnect. Having more than one path for ground is not a problem.

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John

Ponsse

Thom is right on his first assessment. The OP was talking about connecting the "White" wire (neutral) to the EGC at the appliance. The "White wire was already connected to the "Neutral Buss" at the main panel. The main panel will have a main bonding jumper installed which effectively bonds the neutrals and EGC's together at that point. There will be no "objectionable current" on the "neutral" because there is no "neutral". The appliance has no neutral. The "white" wire (neutral) will now become a second EGC just as Thom pointed out in the first place.

There is no "objectionable neutral current" if there is no neutral.

And as to Magnettica stating that parallel paths increase resistance and will prevent OCPD's from operating, this is also not true. Parallel paths will increase current flow. What happens when you put 2 equal resistors in parallel? Their resistance is cut in half, and the current is doubled.

Just don't forget to put some green tape on the white wire.

jrclen

changed my mind about answering.