3 wire circuit off sub panel

[Will Wire]

I am concerned with the safety of connecting a three wire appliance circuit to a subpanel. I installed a sub panel and refed the circuits. After I finished I remembered that the code only allows a three wire circuit to be used if run unbroken to the service. Have I created an unsafe situation? Thank you for your attention to this matter.

 

[Jim W in Tampa]

If your suggesting a range or a dryer then they must be 4 wire regardless of sub panel or not.

 

[Will Wire]

I am refeeding an old three wire circuit.

 

[charlie b]

After I finished I remembered that the code only allows a three wire circuit to be used if run unbroken to the service.

I don't recall having encountered such a rule. Can you elaborate? Where is this likely to be stated in the code? I looked in 250 and 422, and I didn't find it. :-?

 

[Will Wire]

I am refering to the section that allows for three wire circuits for for ranges and dryers in existing situations. 250.140 NEC 2002

 

[charlie b]

I am refering to the section that allows for three wire circuits for for ranges and dryers in existing situations. 250.140 NEC 2002

I see they moved that requirement to an Exception in 2005, but they did not essentially change the requirement. You are specifically referring to sub-paragraph (3). Look at where they put the comma in that sentence. You are OK if the grounded conductor is insulated. Stop reading. You need not read past that comma. You are done. Presuming the neutral wire is insulated, your installation is compliant.

But if you must continue reading, then you are also OK if the grounded conductor is uninsulated and if the branch circuit originates at the service panel.

Does that make sense? Does it put your mind at ease? :smile:

 

[LarryFine]

Charlie, he is rendering the old panel into a sub-panel. This means the source is no longer the main service panel.

T-bird, the only compliant thing to do is replace the 3-wire cable, receptacle, and plug with 4-wire counterparts.

You may ask the inspector to permit the 3-wire to stay. Remember you're using a neutral for grounding, not vice-versa.

 

[mdshunk]

Is that 3-wire circuit SE cable or ungrounded romex? If it's ungrounded romex, you're good to go. If it's SE cable, you need to replace it. I've had inspectors permit SE to remain coming out of a newly hatched subpanel if I taped up the bare conductor completely with white tape and terminated it on the neutral bar. That doesn't square with anything that was ever written in the NEC, but I was grateful for that permission a time or two.

 

[LarryFine]

I've had inspectors permit SE to remain coming out of a newly hatched subpanel if I taped up the bare conductor completely with white tape and terminated it on the neutral bar. That doesn't square with anything that was ever written in the NEC, but I was grateful for that permission a time or two.

I agree.

 

[charlie b]

Charlie, he is rendering the old panel into a sub-panel. This means the source is no longer the main service panel.

I don't think that is what he is talking about. As I see it, there was (and still is) a main panel, and it used to have (but no longer has) a circuit for the dryer. A subpanel was installed, and a branch circuit from the subpanel now feeds the dryer. There was no discussion of how the subpanel itself was installed, nor of the ground and neutral bar connections in the subpanel.

The question, as I understand it, has to do with starting at a subpanel, and feeding a dryer, using the existing a 3-wire dryer outlet. I see no problem with that installation. But the OP was asking if the 3-wire circuit must go to the existing dryer outlet directly from the service panel. It is, I believe, a misinterpretation on the part of the OP, with regard to the wording of 250.140.