Grounding kitchen range to EGC of another branch circuit

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SureFire

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Location
Wake county, NC
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retired IT Systems Engineer
Background:
Single family detached residence built in 1977. Electric range is wired as explained in the exception stated in 250.140. i.e. There is no EGC in the dedicated branch circuit for the range. Therefore, the frame of the range is bonded to the grounded conductor. Circuit breaker is 2-pole, non-GFCI, 50A. Let’s call this circuit A.

There is another branch circuit very near the range whose conductors, hot, neutral, and ground, are 10AWG copper. Let’s call this circuit B. Per Table 250.122, a 10 AWG copper conductor can be used as the EGC in a branch circuit up to and including 60A.

Both branch circuits originate from the same load center. The load center and the range are on opposite ends of the house. No easy crawl space, basement or attic access.

p.s. Because of extensive damage from hurricanes, our state is still using NEC 2017.

Question:
Can 250.130(C)(4) be used to do the following?
  • Replace the NEMA 10-50 receptacle with a NEMA 14-50 receptacle.
  • There will be two cables going into the NEMA 14-50 receptacle. The original 3 wire, 4 AWG aluminum cable. And a new 10-2 with ground copper cable. The hot and neutral conductors of the 10-2 will be capped off and not used. The 10-2’s EGC will be connected to the ground terminal screw of the NEMA 14-50 receptacle.
  • The other end of the 10-2 cable will be joined to circuit B inside an existing J box. The hot and neutral conductors will be capped off and not used. The EGC will be connected to the EGC of circuit B.
  • Inside the J box, label the new 10-2 as ‘Kitchen range EGC only’
  • Replace the range’s power cord with a NEMA 14-50 power cord.
  • Unbond the ground and neutral in the range.
  • Replace the 50A breaker with a 50A GFCI breaker.
  • In the circuit directory (the documentation showing what each breaker protects) for the load center, make a note that the EGC for the kitchen range is connected to circuit B.
 
This doesn't make sense to me:

Single family detached residence built in 1977. Electric range is wired as explained in the exception stated in 250.140. i.e. There is no EGC in the dedicated branch circuit for the range. Therefore, the frame of the range is bonded to the grounded conductor. Circuit breaker is 2-pole, non-GFCI, 50A. Let’s call this circuit A.

Where is your "grounded conductor" coming from? what is "bonded to the frame of the range"?
 
I would say maybe. Are all the boxes plastic or metal? If metal, all conductors of the same circuit need to go through same hole, and if in ferrous raceways, they need to be in the same one.
 
herding_cats said:
Where is your "grounded conductor" coming from? what is "bonded to the frame of the range"?
Click to expand...
Herding_cats. I am sorry if I did not describe it clearly. Currently, the range has a 3 wire, 4 AWG aluminum cable. Two of the wires are connected to the two hot terminal screws of the NEMA 10-50 receptacle. The third wire is connected to the neutral terminal screw of the receptacle. There is no EGC in this cable. Therefore, the grounded conductor is part of this cable and originates in the load center.

Whenever (competent) applicance installers install a new range to a pre-1996, 3 conductor circuit, they open the back of the range and when installing the 3 prong power cord to the range, they take the range’s internal neutral conductor and attach it to the range’s ground screw. Therefore, the range’s frame becomes bonded to the range’s internal neutral, which in turn connects it to the neutral conductor in the cable.

I hope this makes more sense.
 
suemarkp said:
Are all the boxes plastic or metal?
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Suemarkp. The range’s NEMA 10-50 receptacle is surface mounted. So, it does not have a box. The J box mentioned in the original post is metal. All cables coming into this box are NM and are secured to the box using clamp connectors. Outside the box, the cables are secured via staples onto wood members. The cables are not inside an enclosed channel or conduit.

The J box is already bonded to the EGC of circuit B described in the original post.
 
With respect to all members, it is my understanding of forum rules that we no longer publicly question new members qualifications for posting.

To be clear, I am not asking any member how to do something. From years of experience, I have already designed several ways of solving this. The solution I presented here is the most cost effective, but one that if I interpret the NEC one way, it’s valid. But if I interpret it another way, it becomes questionable. And I believe it is this forum that can generate a healthy NEC discussion around this.
 
SureFire said:
With respect to all members, it is my understanding of forum rules that we no longer publicly question new members qualifications for posting.

To be clear, I am not asking any member how to do something. From years of experience, I have already designed several ways of solving this. The solution I presented here is the most cost effective, but one that if I interpret the NEC one way, it’s valid. But if I interpret it another way, it becomes questionable. And I believe it is this forum that can generate a healthy NEC discussion around this.
Click to expand...
The forum rules also do not allow us to assist with DIY projects.

Little Bill allowed the thread for yes no answers which is as far as we can go.

This site is designed for:

  • Electrical Contractors
  • Electricians
  • Engineers
  • Inspectors
  • Instructors
* This NEC� Forum is for those in the electrical and related industries. Questions of a "How-To" nature by persons not involved in the electrical industry will be removed without notice.
Click to expand...
 
Have a professional do it for sure, here is one I just did this week, this person thought they needed a new circuit, In my area houses wired in the 70's mostly have a EGC in the NM cable , they just did not use a 4-wire receptacle back then, the original installers usually cut the EGC really short,.
I had to do some testing to make sure the EGC made it all the way to the panel, and I had to carefully pull up on the range cable and strip back some sheath to splice on some #10.
If you have the area to the range plug completely clear and the area around panel clear for the electrician it saves time.

1762546654759.png1762546615805.png1762546486579.png
 
SureFire said:
And I believe it is this forum that can generate a healthy NEC discussion around this.
Click to expand...
Not with a DIYer. Even as professionals, we don't just pick up a Code book, read it, and are able to know how to do something. It takes years of experience before one can know what the NEC actually means. It may seem like black and white to you, but it often isn't.

Further, we know EXACTLY what you have and are trying to do. We've delt with 3 wire and 4 wire range and dryer receptacles probably hundreds and hundreds of times. Depending, it may not even be necessary to do anything.

Do yourself a favor and contact an EC.

-Hal
 
SureFire, please try diychatroom.com, I think you will find a good bunch of knowledgeable people there.
 
It would be easier to hire a local electrician and have him install it. The third conductor in what you call "circuit A" is the ground. It goes back to the main where the ground and neutral are bonded. Note the the service drop going to your home is not 4 wires: Does that make sense?
 
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