dryer supply issue in 1970s house

[kgilfilen]

I just discovered, after tracing the 10/3 cable from a three-prong dryer receptacle that it connected to a non-grounding 3-conductor cable in a J box. That cable runs to the main panel. I have several questions, but I understand that code requirements changed at some point in the 1990s, and a regular copper element was then required for grounding, separating the ground function from the neutral conductor.

My question is,

1) if I'm extending the cable run, is it okay to just use 10/3 cable and not use the ground wire? 2) Would it be a good idea to add a separate copper wire from the panel to the outlet, if I rewired the cable at the panel, putting the neutral wire on the neutral bar?
3) Or should I just leave things as they are?

The reason I haven't mentioned running a new cable from the panel, rather than the J box, is that the home run is behind sheetrock, and not easily accessed.

Thanks!

 

[roger]

Re: dryer supply issue in 1970s house

I would leave things the way they are.

I'm not quite sure I understand your statement of "non-grounding" cable. Are you talking about a three conductor cable without a bare conductor, if so, this was the proper installation in the 70's.

A 10/3 with out ground was the norm.

Roger

 

[bphgravity]

Re: dryer supply issue in 1970s house

Typically speaking, if you perform new work to existing system, it needs to be brought to the governing code. Other than direct replacement of the receptacle or dryer cord itself, any wiring additions or changes will have to be performed to Article 250.134 and 250.138.

If you plan on adding an equipment grounding conductor, it will have to be done according to 250.130(C). If you just want to leave it as originally installed, 250.140 provides the requirements for this existing installation.

 

[kgilfilen]

Re: dryer supply issue in 1970s house

Roger, yes, I meant the cable did not have a bare conductor. It has a ground, I didn't write that correctly.


bphgravity: thanks for the references. I will have to drop by the Home Depot to review their NEC book, as I don't have one. I am thinking now that I may bring a new cable from the panel anyway. What's a little drywall work gonna hurt? Then it'll be wired correctly. But if a simple bare-wire ground is legal, and a simple rewiring at the panel, then it'd be alot easier.

While I'm here, I have another question for you guys. I've noticed a lot of circuits have runs of 3 conductor cable (not just in 3-way switch circuits). This does not originate at the panel, where there are mostly just 2 conductor cables feeding circuits. Is this a technique for using one cable instead of two in various different locations? How does it work?

Thanks in advance.