Uninsulated Grounded Conductor

[wwhitney]

(2020) 310.3(D) says that conductors not permitted elsewhere in the Code to be covered or bare shall be insulated.

250.140 is about bonding the frame of a clothes dryer or range to the EGC, but the exception allows bonding to the grounded conductor for existing installations without an EGC, including the case of an SE-type cable originating at the service entrance with a bare, covered grounded conductor.

But where is that bare, covered grounded conductor for the branch circuit itself allowed? Is it just implicit in the wording of 250.140 Exception, or is it more explicit elsewhere?

And if only implicit, does that mean that if you don't bond the frame of the clothes dryer or range to the grounded conductor, because you've run a separate EGC per 250.130(C), the bare, covered grounded conductor is no longer allowed per 310.3(D)? Which would mean it's pointless to do a 250.130(C) EGC in such a case, you'd need to run a new 3 conductor plus ground wiring method.

Cheers, Wayne

 

[Dennis Alwon]

Well 310.3(D) states where permitted elsewhere in the code.... Isn't 250.40 elsewhere and doesn't it allow the bare neutral. Maybe I am missing something but it appears to be implicit, as you say, in 250.140 exception

 

[wwhitney]

Yes, it's implicit, 250.140 doesn't actually say the bare grounded conductor is allowed in the exception, it just says it's OK to bond the frame to the bare grounded conductor (a subtle distinction).

So if it's that's the only allowance for the uninsulated grounded conductor, what about the questions in my last paragraph?

Cheers, Wayne

 

[Dennis Alwon]

Again 250.130(C) allows a bare equipment grounding conductor so wouldn't that be allowed per 310.3(D). I see it as if a section allows an installation then 310.3(D) is meaningless.

 

[wwhitney]

The last paragraph in the OP was about this scenario: say you have a range with an ungrounded supply consisting of a type-SE cable with 2 insulated ungrounded conductors and a bare grounded conductor (edit: and say it originates at the service panel). That's permitted by 250.140 Exception, but you don't like that, so you use 250.130(C) to extend the properly sized EGC from another circuit to the range supply junction box. And you insulate the bare grounded conductor where exposed, to avoid any neutral/ground contact.

So is that arrangement OK, with the bare grounded conductor in the SE supply cable? Or was that grounded conductor only allowed to be bare because one was using the 250.140 Exception allowance to bond the case of the range to the grounded conductor? And now that the case of the range is properly bonded to the EGC, there's no longer any permission to have a bare grounded conductor, as you are no longer using the Exception that mentions it.

Cheers, Wayne

 

[Dennis Alwon]

Now I get you.... That has come up many times in our area and the inspectors would allow that install. IMO, I don't think the NEC is clear on that issue. One has to think is it not a better install then before because that neutral was bare then so why should it matter if you add an equipment grounding conductor.

I think this is really an authority having jurisdiction call.

 

[wwhitney]

Thanks, I agree. I'm also wondering if there are other places in the NEC that allow a bare grounded branch circuit or feeder conductor.

Cheers, Wayne

 

[Dennis Alwon]

Other than service conductors, as you already know, I don't think there are other areas where it is allowed. Maybe on some high voltage cables... IDK

 

[Eddie702]

Only bare grounded conductor in the service conductors or bare grounded conductor in the existing 3 wire to a range or drier (if using SE cable) If using romex , Ac cable or MC the grounded conductor must be insulated is my understanding

 

[shortcircuit2]

250.130(C) is deleted in Massachusetts.

 

[tortuga]

say you have a range with an ungrounded supply consisting of a type-SE cable with 2 insulated ungrounded conductors and a bare grounded conductor (edit: and say it originates at the service panel). That's permitted by 250.140 Exception, but you don't like that, so you use 250.130(C) to extend the properly sized EGC from another circuit to the range supply junction box. And you insulate the bare grounded conductor where exposed, to avoid any neutral/ground contact.

This is a standard practice I see this all the time.
Ill add that some residential ranges no longer use a neutral so recently I have bypassed this issue with using a 6-50 receptacle.

250.130(C) is deleted in Massachusetts.

Yeah i think the reasoning is 250.130(C) 'grounding taps' are hard to keep in service.
For example:
I have found in older homes these 250.130(C) 'grounding taps' are almost always attached to the existing bare copper water pipe bonding wire with a split bolt in basements and crawl spaces.
In the case of a residential service panel upgrade from 100 Amp to 200 amp the water pipe bond is required to be upgraded and installers tend to snip the old one off and not re-bond it.
Or plumbers re-plumbing a house with PEX have an electrician remove the bond and install ground rods.

I discovered that while troubleshooting some energized ECG's more than one time.
I feel like there is no reason to ban it just add a requirement for labeling .