Required to upgrade to 4 wire sub panel feeder?

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JLH

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I was recently asked to install a generator for a home that had a three wire feed from the main panel to a sub panel. This was done by installing a disconnect between the existing meter base and the commercial side of the ATS. The ATS then fed the main panel. The gen. was sized to carry the total load of the home. I planned to re-feed the sub panel as a four wire system to seperate the neutrals from the egcs. As my requested work only involved upgrades to the main panel, was it required by code that I upgrade the sub panel system at that time? I was able to convince the homeowner to allow the upgrades but was unsure if it was in fact required by code.
 
I would say this depends on the building department/AHJ. Someone would most likely have to determine the existing installation a safety hazard and put in writing a determination to repair/replace it.


I would also say, that it is not in the original scope of your work, so you are not responsible for it. If you have to perform work in that panel, I would also say the inspector has a right to write a citation. Who he writes that citation to has been a bone of contention here on this site.

Me, I would write it to the property owner, as the electrician of record did not install the violation. Not all agree though.
 
It seems to me that the ATS would be required to be rated as service equipment and have the neutral bonded to the grounding electrode system at the ATS and the "main" panel would be made a remote distribution panel and fed with 4-wire and the remote panels downstream of that also fed with 4-wire. :)
 
That is how it was done. I was just unsure what the code actually required and have had a problem finding out locally. I want to give an accurate answer to the next customer when asked if it is required or just best practice. Thanks for the fast response from you both.
 
I mis-spoke. We have three wire from meter to disconnect where bonding takes place. Four wire to ATS, from gen. to ATS, from ATS to main, and from main to sub. Does this sound right?
 
JLH said:
I mis-spoke. We have three wire from meter to disconnect where bonding takes place. Four wire to ATS, from gen. to ATS, from ATS to main, and from main to sub. Does this sound right?
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Yes. I agree with Larry. And I also welcome you to the Forum. :)
 
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