Gallluup Poll: R U comfotable connecting frame to grounded conductor ?

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PowerLimited

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Official Galluup Poll:
Per 250.140 Exception, are you truly comfortable bonding frame of kitchen stove to grounded conductor ?

Answer choices:

A) Yes, truly comfortable

B) maybe, maybe not

C) No, not truly comfortable
 
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250.140 Code

250.140 Code

Chapter 2 Wiring and Protection :: ARTICLE 250 Grounding and Bonding :: VII. Methods of Equipment Grounding


250.140 Frames of Ranges and Clothes Dryers.


Frames of electric ranges, wall-mounted ovens, counter-mounted cooking units, clothes dryers, and outlet or junction boxes that are part of the circuit for these appliances shall be connected to the equipment grounding conductor in the manner specified by 250.134 or 250.138.


Exception: For existing branch-circuit installations only where an equipment grounding conductor is not present in the outlet or junction box, the frames of electric ranges, wall-mounted ovens, counter-mounted cooking units, clothes dryers, and outlet or junction boxes that are part of the circuit for these appliances shall be permitted to be connected to the grounded circuit conductor if all the following conditions are met.


(1)
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The supply circuit is 120/240-volt, single-phase, 3-wire; or 208Y/120-volt derived from a 3-phase, 4-wire, wye-connected system.

(2)
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The grounded conductor is not smaller than 10 AWG copper or 8 AWG aluminum.

(3)
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The grounded conductor is insulated, or the grounded conductor is uninsulated and part of a Type SE service-entrance cable and the branch circuit originates at the service equipment.

(4)
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Grounding contacts of receptacles furnished as part of the equipment are bonded to the equipment.

 
I think the misunderstanding of how and why we use 3 wire in some places and 4 wire in others creates more issues than when practically everything was 3 wire. People not connecting the bonding jumper or failing to remove it when they did not know any better is the problem here.

Run into a mobile home one time that had a bad neutral in the feeder, the bonding jumper was not removed in the dryer, so the dryer EGC was carrying the entire neutral load of the home. One day when the dryer got unplugged guess what happened to many of the electronics in the house once that neutral path was interrupted?
 
iwire said:
Exactly that, no worry from me at all. The range and dryer in my own home are 3 wire and I do not worry a bit.
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Nor do I (worry). If I had a pacemaker, I might think differently.
 
I believe that Don posted that there was no historical evidence that a proper 3W circuit with proper bonding had ever been a shock hazard or caused a death when the code was changed. 1996 NEC IIRC..????
 
jumper said:
I believe that Don posted that there was no historical evidence that a proper 3W circuit with proper bonding had ever been a shock hazard or caused a death when the code was changed. 1996 NEC IIRC..????
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Not too surprising either, but at same time it also did not make much sense why everything else was a strict no no, to even think of using the grounded conductor for equipment grounding, and now you can't do it with buildings supplied from another building anymore either.
 
kwired said:
Not too surprising either, but at same time it also did not make much sense why everything else was a strict no no, to even think of using the grounded conductor for equipment grounding, and now you can't do it with buildings supplied from another building anymore either.
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Just to be clear, IIRC Don's statement was for ranges/dryers only. Not arguing, just clarifying what I think I remember he said.
 
jumper said:
Just to be clear, IIRC Don's statement was for ranges/dryers only. Not arguing, just clarifying what I think I remember he said.
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I know, but what I was trying to point out was the apparent trend toward eliminating all use of the grounded conductor beyond service equipment for equipment grounding purposes, which I think has been achieved outside of exceptions for existing installations.

It kind of makes sense and is consistent with the rest of the code even if people don't like the fact they have to use an additional conductor in places where they never had to before. My understanding for the allowance of only a three wire circuit to ranges and dryers went back to WWII and wanting to save on copper. I don't think today's NEC CMP's would care one bit about how much material may be saved when considering such a rule.
 
PowerLimited said:
Official Galluup Poll:
Per 250.140 Exception, are you truly comfortable bonding frame of kitchen stove to grounded conductor ?

Answer choices:

A) Yes, truly comfortable

B) maybe, maybe not

C) No, not truly comfortable
Click to expand...

...if its code compliant, I'm OK with it. If you post multiply choices, you can start a poll. You start a poll by clicking the box 'poll thread' at the bottom of the page before you post, and choose how many choices are in the poll. Its easy :)
 
nonmetallic sheath cable, putting the unused egc to use...

nonmetallic sheath cable, putting the unused egc to use...

Relative to 250.140 Exception, and the NEC Handbook Commentary to 250.140 Exeption, I am noting the following excerpt from that commentary, quote:

The grounded circuit conductor of an existing branch circuit is permitted to be used to ground the frame of an electric range, wall-mounted oven, or counter-mounted cooking unit, provided all four conditions of 250.140, Exception, are met. The exception can be applied only where the existing branch-circuit wiring method does not provide an equipment grounding conductor. There are many existing branch circuits in which nonmetallic sheath cable with three insulated circuit conductors and a bare equipment grounding conductor was used to supply a range or clothes dryer. The bare equipment grounding conductor was simply not used because it was permitted to ground the equipment with the insulated neutral conductor of the NM cable. This “extra” conductor results because the bare conductor in a Type NM cable is to be used only as an equipment grounding conductor and cannot be used as a grounded (neutral) conductor in the same manner as is permitted for the uninsulated conductor in Type SE cable.
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Concerning the above quoted excerpt, from NEC Handbook Commentary to 250.140 Exception, and concerning the above-referenced scenario of a nonmetallic sheath cable with three insulated circuit conductors and a bare equipment grounding conductor used to supply a range, and where the bare equipment grounding conductor was simply not used, I have the following question.

If I now want to install a new range, and if I want to use a 4 wire configuration with the new range ( bonding strap removed, i.e., stove frame NOT bonded to circuit neutral), would I be code compliant if I put the currently unused bare egc to use…and replace the existing 3 wire stove receptacle with a 4 wire receptacle? It seems like a ‘no brainer’ but still I would like to hear any affirmation, opinion, etc., on this. Thanks.
 
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PowerLimited said:
Relative to 250.140 Exception, and the NEC Handbook Commentary to 250.140 Exeption, I am noting the following excerpt from that commentary, quote:



Concerning the above quoted excerpt, from NEC Handbook Commentary to 250.140 Exception, and concerning the above-referenced scenario of a nonmetallic sheath cable with three insulated circuit conductors and a bare equipment grounding conductor used to supply a range, and where the bare equipment grounding conductor was simply not used, I have the following question.

If I now want to install a new range, and if I want to use a 4 wire configuration with the new range ( bonding strap removed, i.e., stove frame NOT bonded to circuit neutral), would I be code compliant if I put the currently unused bare egc to use?and replace the existing 3 wire stove receptacle with a 4 wire receptacle? It seems like a ?no brainer? but still I like to hear any affirmation, opinion, etc., on this. Thanks.
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Sure, just make sure the other end of the bare conductor is actually connected to an EGC, or the neutral bus in the service equipment.
 
kwired said:
I think the misunderstanding of how and why we use 3 wire in some places and 4 wire in others creates more issues than when practically everything was 3 wire. People not connecting the bonding jumper or failing to remove it when they did not know any better is the problem here. Run into a mobile home one time that had a bad neutral in the feeder, the bonding jumper was not removed in the dryer, so the dryer EGC was carrying the entire neutral load of the home. One day when the dryer got unplugged guess what happened to many of the electronics in the house once that neutral path was interrupted?
Click to expand...
with a bad neutral, voltage at outlets can go up to 180 volts through backfeed from devices powered by the other phase.
 
jumper said:
Actually the voltage could higher, all but ~240V is possible on a 125V device wired to a 120V MWBC with a broken/bad neutral. Depends on the series impedance of the loads when the noodle is gone.
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If there was no load at all on L1, then all of its associated 120V receptacles and outlets could see the full 240V from hot to "neutral", but no voltages above 120V to ground will appear. And nothing on a 120 volt circuit powered from L2 would see any voltage from hot to "neutral" until the first victim :) was connected to L1.
 
GoldDigger said:
If there was no load at all on L1, then all of its associated 120V receptacles and outlets could see the full 240V from hot to "neutral", but no voltages above 120V to ground will appear. And nothing on a 120 volt circuit powered from L2 would see any voltage from hot to "neutral" until the first victim :) was connected to L1.
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Huhhh. Can you reword that?


Roger
 
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