Art. 250.122(B)

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marcerrin

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I’m hoping for a little clarification on an issue that came up this week.
We finished a kitchen remodel rough in on a newer home and called it in for inspection. Getting new home runs to the kitchen would have required an conduit on the exterior of the home, so the HO, naturally, wanted us to try and use existing circuits. Luckily for us, the original electrician had 4 small appliance circuits plus, 20 amp DW circuit , 20 amp Disp circuit , 20 amp refer, 10/3 for the oven and 6/3 for the range. I was able to utilize the existing circuits for all the new stuff. The existing oven circuit (10/3) was no longer needed because they went with a free standing range, so I changed the breaker to a 2/p arc-fault and branched from it with two 12/2’s to feed a coffee maker and additional disposal.
The inspector didn’t call me on this, but said, “technically that is not legal according to 250.122(b).” In my opinion this article is clearly referring to voltage drop situations only and this inspector is interpreting this article incorrectly.
He says that the EGC needs to be #10. I’ve email with him quoting the article as well as the verbiage that follows it in the handbook, but he insists that his interpretation is correct.
This hasn’t been a contentious argument, and he’s been generaous with his time, but I don’t believe I’m wrong.
What say you?
 
The inspector is correct as the code does not specifically state for VD anymore. What you did is done all over the place but IMO, it is not a safety issue. This is a perfect example of when the code wording does not fit the application. There is, IMO, no reason to have to upsize the equipment grounding conductor in this situation but the code does say you must.
 
I would have to dig deeply in the library, but the wording of 250.1122(B) has changed overt he years at times stating "for voltage drop"
(I know that was the case in '93) to simply "increased" (for any reason)
 
Unless the 10-3 was very old it would have a 10 awg EGC. The part of the run that used the 10-3 is the only part that requires the 10 EGC. Once you splice it to the 12s, the ungrounded conductors are no longer oversized and the EGC in the 12-2 is fine for the circuit.
 
Don may be correct-- I assumed the equipment grounding conductor was not #10 . This is usually the case where the range wire is used for the conversion. Again it is not a safety issue with a short run, IMO.. It was good that the inspector let it ride.
 
marcerrin said:
The inspector didn’t call me on this, but said, “technically that is not legal according to 250.122(b).” In my opinion this article is clearly referring to voltage drop situations only and this inspector is interpreting this article incorrectly.
He says that the EGC needs to be #10. I’ve email with him quoting the article as well as the verbiage that follows it in the handbook, but he insists that his interpretation is correct.
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As Don stated modern 10/3 has a #10 EGC so there isn't an issue with 250.122(B). If he was referring to the EGC in the 12/2 well that wouldn't matter either because the EGC is not required to be larger than the phase conductors.
 
Dennis Alwon said:
Don may be correct-- I assumed the equipment grounding conductor was not #10 . This is usually the case where the range wire is used for the conversion. Again it is not a safety issue with a short run, IMO.. It was good that the inspector let it ride.
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Assuming that the 10-3 had an EGC, it would be full size if it was made after 1969. If it didn't have an EGC, you could not use it to feed a multiwire circuit.
 
marcerrin said:
Yes, the 10/3 has a full size #10 EGC.
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So as you stated in the OP you are correct and the inspector is wrong because the point is moot. When applying 250.122(B) you have gone from a 12 AWG phase conductor and a #12 EGC for a ratio of 1:1 to a #10 AWG phase conductor and #10 EGC which is also 1:1. :)
 
Agreed-- the inspector needs to know that the 10 equipment grounding conductor with the 10/3 is appropriate and then you downsized appropriately from 10 equipment grounding conductor to 12 equipment grounding conductor. Of course, a 20 amp breaker must be used.

The entire circuit does not need to be sized for the increased conductor size, just the part of the circuit that was increased.

Now if you had a 8/3 se cable with a reduced equipment grounding conductor, then you would have an issue
 
don_resqcapt19 said:
Unless the 10-3 was very old it would have a 10 awg EGC. The part of the run that used the 10-3 is the only part that requires the 10 EGC. Once you splice it to the 12s, the ungrounded conductors are no longer oversized and the EGC in the 12-2 is fine for the circuit.
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Can anyone think of engineering reason for this requirement?
 
Thanks for all the replies. I’ve brought up most of these points with him, but he’s not budging. I may speak to the lead inspector this week and bring it up.
 
Inspectors make mistakes too and in this case he's wrong. Since it had no impact on your installation it's a toss up as to whether or not going over his head is worth the effort.
 
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