Inspected an older house yesterday that has a 100 amp service with 2 awg aluminum service entrance cable going into a small 100 amp service panel with no main disconnect.
The current owner, who appears to have done the wiring himself, has now installed a new 200 amp panel, with 200 amp main disconnect next to the old 100 amp panel. He has connected the feed to the new 200 amp panel directly to the main terminal lugs of the old 100 amp panel, eliminated distribution to the house from the old 100 amp panel and essentially made the 100 amp panel a junction box for the 200 amp panel. All distribution to the house now goes out from the 200 amp panel via the original 100 amp service panel.
Am I correct in my thinking that this is an incorrect application? Shouldn’t the main disconnect be 100 amp or else upgrade the entrance cable to 4/0 awg and overall service to 200 amp?
I think it’s fair to say that in the areas in which you inspect, the power companies (not the local jurisdictions) require an inspection after modifications to the service equipment. I think it is also fair to say that this work was done without the benefit of such inspections. This can lead to the new owners getting their power shut off without notice. Just a head’s up on that. Oh, and by the way… what he’s done there is not proper, and it doesn’t sound like he changed the meter can either. That has a max rating too.
Am I correct in my thinking that this is an incorrect application? YES
Shouldn’t the main disconnect be 100 amp or else upgrade the entrance cable to 4/0 awg and overall service to 200 amp? **Dont they believe in permits where you live. That whole system is wrong. I always recommend that the client check for permits for any upgrades that are done. In this case it will just make your case stronger for replacement. You are looking at one hell of a potential fire hazard there, not to mention other numerous violations (I’m sure) **
Am I correctly understanding from your description that the main disconnects are downstream from the branch circuit disconnects — or that the main disconnects, upstream from the barnch circuits, are 200 amp?
No the meter can was not changed either. There were enough other electrical issues that evaluation by an electrician was warranted even without this particular issue, but I just wanted to double check my thinking on this item. Thanks, Marc.
No, the branch circuits are in the new 200 amp panel after the 200 amp disconnect. The 200 amp panel is being fed through the old 100 amp service panel, but the branch circuits in that panel have been eliminated. The old 100 amp service panel is now essentially a junction box (with no cover any where to be found, by the way). The service to the house appears to still be 100 amp.
I would have liked to do that, Joe, but I dropped my camera and blew out my flash and didn’t have a spare camera. So my pictures in that area of the dank 100 year old basement were very dark. Have to go out and buy a new camera now. You just can’t replace the bulb like in the old days.
Was the supply for the “sub” panel protected in the main sevice panel by a 100 amp disconnect? Though it would be nice, the NEC does not require a disconnect in both panels.
Was the first 100 amp panel actually used as a “junction box” or was the 200 amp panel fed from a disconnect inside the 100 amp panel?
Sounds like the owner needed more circuits and added the 100 amp panel, then decided that it still wasn’t enough and went for the 200 amp panel. Either way, it SHOULD be protected inside the original service equipment by a 100 amp disconnect. Simply adding a 200 amp panel after the main panel does not mean that you have 200 amp service at the home. For the service to have been upgraded to 200 amps, the SEC, meter and drop should hvave been changed out if they were not rated at 200 amps.
Yes, this is an “unconventional” installation and it would be better to be properly replaced with an panel appropritely sized to the service available to the home (or the service upgraded). However, a properly installed “sub” panel with a 200 amp main disconnect will not constitute a overcurrent hazard for the meter, SEC, service drop, etc. if it is protected by a disconnect properly sized for the lowest rating of all components involved, assuming that it is not double tapped prior to the main disconnect in the first panel. A 200 amp main in this panel, if protected by a 100 amp disconnect at the original source, would be nothing more than a big conductor that can carry more current that it will ever see.
