NM cable colors

[newinbiz]

In the NEC, I cannot find any clarity regarding the color standards for a single phase 240V, 30A receptacle. Would a standard NM 10/2 (bk/wh) cable (romex) with ground be acceptable? If not, do I use a 3/C NM cable (bk/rd/wh) and just tape off the white? Thanks

Bill
Tacoma, WA

 

[infinity]

Re: NM cable colors

You could use either. However if you were to use the 10-2 cable than the white would need to be re-identified as per 200.7(C)(1).

 

[jwelectric]

Re: NM cable colors

What are you feeding with that cable? Something like a dryer would need all four wires.

250.140 Frames of Ranges and Clothes Dryers.
Frames of electric ranges, wall-mounted ovens, counter-mounted cooking units, clothes dryers, and outlet or junction boxes that are part of the circuit for these appliances shall be grounded in the manner specified by 250.134 or 250.138.

 

[iwire]

Re: NM cable colors

However if you were to use the 10-2 cable than the white would need to be re-identified as per 200.7(C)(1).

At no time that I am aware of did the NEC allow 10/2 NM to feed a dryer.

The rules allowed using the neutral to ground the frame, the neutral is required to be insulated.

You would have to run 10/3 and not use the bare, of course at that point you might as well have used the 4 wire outlet and dryer cord.

 

[infinity]

Re: NM cable colors

The original question said nothing about a dryer, just a 240v, 30amp receptacle, hence my response that the feeder could be a 10-2 cable. If it were for a dryer than Bob and JW would be correct that it couldn't be a 10-2 cable.

[ April 19, 2005, 07:15 PM: Message edited by: infinity ]

 

[iwire]

Re: NM cable colors

JW and I are both thinking dryers but the opening post only said a 240 volt 30 amp outlet.

A straight 240 outlet could use just 10/2, sorry for assuming.

 

[jwelectric]

Re: NM cable colors

Originally posted by iwire:

The rules allowed using the neutral to ground the frame, the neutral is required to be insulated.

250.140 exception (3) The grounded conductor is insulated, or the grounded conductor is uninsulated and part of a Type SE service-entrance cable and the branch circuit originates at the service equipment.

 

[iwire]

Re: NM cable colors

JW have you ever seen 10/2 SE?

I thought not.

[ April 19, 2005, 08:01 PM: Message edited by: iwire ]

 

[hardworkingstiff]

Re: NM cable colors

We used to run 8/3 SE AL for dryers (back in the 70's, God I'm old, lol).

 

[newinbiz]

Re: NM cable colors

Hey guys. Thanks for the input and direction. The 240V, 30A outlets would be convenience receptacles for shop equipment, not for a dryer...which leads me to another question....How many 30A,240V outlets can be on one branch circuit? Thanks.

Bill

 

[kiloamp7]

Re: NM cable colors

Well, if using 30A branch ckts.,its a design decision. As many as you want.

 

[mc5w]

Re: NM cable colors

Depends upon how many things you want to run at the same time, what is known as the noncoincident load rule. The 180 volt-ampere per receptacle rule for GENERAL PURPOSE receptacles limits you to 32 240 volt receptacles on a single circuit. However the general purpose rule does not apply to a receptacle that is installed for a particular appliance or machine.