Once again, I encountered some clever person who was able to "create" 110 in a 220v system by grounding the neutral screw to the box.
While I corrected the situation, I was challenged to show where this dangerous practice was banned. After all, the NEC does allow uninsulated neutrals (grounded conductors).
Other than noting that "raceways" contain, rather than act as, conductors, and noting that the code has no ampacity tables for EMT, I am at a loss as to just where this practice is explicitly banned.
Considering that I was once fired for objecting to this practice, I sure would like some better references. Any suggestions?

John, where in the NEC is it stated, that a neutral(grounded conductor) can be bare in other than a service entrance location?

I'm thinking
'seperatley derived receptacle'

Explicity banned.

I do not recall seeing such a statement, but neither do I see where explicity permitted.

The only reference I am aware of - of metal raceways being a conductor is for Equipment Grounding Conductors (EGC), 250.118.

Along the above thought; 250.24(A)(5) does not permit the Grounded Conductor to be re-grounded after the Service Disconnecting means, but does have exceptions. I do not think most installations where the raceway would be used as the neutral could be free of being grounded somewhere.

I do not see metal raceways as conductors in Article 310, Conductors for General Wiring.

This maybe come a problem in future codes. Starting with the '05 code, the "uses permitted" will be deleted from some code articles. The idea is that if the code does not prohibit the installation, it will be permitted.
Don

Would the previously allowed method of wiring a clothes dryer be considered similar?

There was no GC, just two hots and an EGC. The frame of the unit could become hot.

Now, the requirement is two hots, a GC and an EGC.

(Or am I attempting to compare two different things?)

P. S. John: What was your solution to fix this? Pull a new, separate conductor?

[This message has been edited by ThinkGood (edited 08-06-2003).]

Funny that this topic surfaced....
Years back, I had a employee who "went on his own".

Got a call from a job he worked on, arcing behind the clothing racks along the wall. Went to the site, saw visable arc tracking on the 1/2" EMT....went to the AC receptacle, opened the 1900 cover. A new cost cutting installation method.... a great discovery.

One (1) #10 THHN, black, on the single receptacle, a 6" piece of white, from the neutral recept terminal, to a ground screw in the box. Gee, 120 volts at the outlet..

Hmm, materials cost saved? maybe $10.00, possible fire damage? priceless.

Now if he only made sure the setscrews were all tight, he might have escaped!

THe "old timers" used to call this practice "gipping the ground" "who needs the white wire", "The BX sheath is good enough for a return path".

John

Article 200.2: All premises wiring systems, other than ..... shall have a grounded conductor that is identified in accordance with 200.6. 200.6 seems to only list "insulated" conductors. The definition of "conductor, insulated" in article 100 would not include conduit.

I left out a lot of exceptions in 200.2 that I didn't feel like typing.

Thanks for the feedback.

Where the NEC discusses the marking of the grounded conductor, is the color shall be, where insulated,.... This seems to suggest that the neutral need not be insulated. I agree that I've only seen an un-insulated "neutral" on the POCO side of the service.

How did I "convert" 240 to 120? I was lucky in that the panel was a main panel, so the ground bus also qualified as a neutral bus. All I had to do was identify one of the wires, mark it, and terminate it in the appropriate places.
On a follow-up visit, the manager told me that the maintenance guy had tried to get in the apartment to see "what I'd done," but she had refused him. I thanked her, explaining that it had been necessary for me to do work at both the apartment and the panel in order to make the change.

i suppose it's time to throw the proverbial monkey wrench in and ask about a meter/panel back to back via EMT ?

yup, it's a NOOOOooooOOOdle guys

now noodle out of it...

never mind

[This message has been edited by Redsy (edited 08-19-2003).]

Well, what about 110.5? An EGC is not "normally used to carry current", so use of emt or other raceways as an EGC is not a violation of this section, but a neutral is "normally used to carry current". What material is that particular emt made of?

(I was directing this response to the original question rather than sparky's monkey wrench. I don't know how to noodle out of that one )

[This message has been edited by eprice (edited 08-19-2003).]

A couple of years ago I did some work at a small custom furniture shop. Someone had added some receptacles, ceiling fans and lights. They just found a wire in a J box,tied to it and tied the other wire to the building bar joist steel. Sometimes one leg of three phase , whatever was handy. No neutral, no real ground.

I corrected everything I touched and provided a written warning about the situation. The place burned to the ground a few months later. Fortunately no one got electrocuted.

Hi Guys,

IMO;

The code can not state this rule exclusively and simply because there are exceptions to the rule.

I think I would have a hard time convincing a jury of our peers that the code does not expressly prohibit uninsulated grounded conductors, with only a few exceptions which are clearly referenced in 310.2 Exception. Consider the overwhelming evedence that is plainly stated;

NEC 2002
300.3 Conductors.
(A) Single Conductors. Single conductors specified in Table 310.13 shall only be installed where part of a recognized wiring method of Chapter 3.

310.2 Conductors.(A) Insulated. Conductors shall be insulated.
Exception: Where covered or bare conductors are specifically permitted elsewhere in this Code.
FPN:See 250.184 for insulation of neutral conductors of a solidly grounded high-voltage system.
(B) Conductor Material. Conductors in this article shall be of aluminum, copper-clad aluminum, or copper unless otherwise specified.


ARTICLE 310 Conductors for General Wiring
310.11 Marking.
(A) Required Information. All conductors and cables shall be marked to indicate the following information, using the applicable method described in 310.11(B):
(1) The maximum rated voltage.
(2) The proper type letter or letters for the type of wire or cable as specified elsewhere in this Code.
(3) The manufacturer’s name, trademark, or other distinctive marking by which the organization responsible for the product can be readily identified.
(4) The AWG size or circular mil area.
FPN:See Conductor Properties, Table 8 of Chapter 9 for conductor area expressed in SI units for conductor sizes specified in AWG or circular mil area.
(5) Cable assemblies where the neutral conductor is smaller than the ungrounded conductors shall be so marked.

With these examples above, there is no way one could confuse conduit as being an acceptable grounded conductor!

Thanks,
Dave