250.140

[A/A Fuel GTX]

I've got a situation where an existing 3 wire dyer circuit needs a new receptacle installed along with the dryer cord itself. Originally this circuit was dervived from the service equipment however due to a new service being installed, the circuit now is supplied by a sub panel. The new meter section has a main breaker as part of it so the old service equipment is now a sub panel. In reading the requirements of 250.140, to use an existing circuit it must be originated from the service equipment. Due to accessibilty issues, it would be very difficult to run a new 4 wire branch circuit to this location. There are no parallel path issues here because SE-R is run to the sub panel and NM cable is run to the original dryer receptacle. Am I OK to just replace the cord and receptacle and keep the dryer bonded to the grounded conductor?

 

[raider1]

Re: 250.140

If you take a look at part (3) of 250.140 Exception:, you will see that the grounded conductor must be insulated or if not insulated, part of a Type SE cable originating at the service equipment.

This means that if the branch circuit grounded conductor is insulated it can come from a "sub-panel". Your post talks about NM cable run for the dryer, which would no have a insulated grounded conductor and not acceptable under the exception.

I would have to say no, you could not just replace the receptacle and cord if you don't meet the requirements of 250.140 Exception.

Chris

 

[tph06784]

Re: 250.140

As long as the NM was 10/3 it would have an insulated grounded conductor and as long as it also met the other three conditions for the exception in 250.140 you could leave the frame bonded to the grounded conductor.

 

[A/A Fuel GTX]

Re: 250.140

So are you saying that if I had SE-U coming from the service equipment it would be allowed but not from the sub panel because the grounded conductor it is not insulated? Which brings me to another question....where do we find the allowable ampacities for SE-U/R when used as a branch circuit?

[ January 19, 2006, 03:03 PM: Message edited by: m73214 ]

 

[raider1]

Re: 250.140

I agree that if you have 10/3 NM cable that you would have an insulated grounded conductor and be able to leave the frame of the dryer bonded to the grounded conductor.

However the original post referred to a three wire dryer circuit which would be a 10/2 NM with ground, if I understand m73214's original post correct. This is the reason that I said that NM cable could not be used to meet this requirement.

The way 250.140 Exception is written you would be able to use a Type SE cable if it originated at the service equipment, but not at a "sub-panel".

The conductors of SE cable are XHHW-2 type conductors, so you would use the column for XHHW-2 conductor for ampacities, keeping in mind the temperature limitations for the terminations.

Chris

 

[A/A Fuel GTX]

Re: 250.140

Yes, the original circuit was a 10-2 with ground so I can't use it because of the uninsulated ground. However, during the topic dialog both scenarios were addressed and that is a good thing. Thanks for your inputs.