You're assuming information not in evidence. The OP simply said that he was upgrading the service from 100A to 200A. It is quite possible that there is nothing wrong with the current panel. Using it as a sub would save considerable work.
Again, you're assuming information not in evidence. Wires are
*always* too short to go where they weren't intended to go. Some may reach, move those. If he's blessed and they all move without "stretching" the whole point of the sub/j-box is moot.
The old box is a Federal Pacific 100A. I haven't had any problems with the breakers - they trip when they should, but when I go to sell the house, I know it's going to be an issue. Also, the panel is full. I need to add more circuits. There's already a sub panel with 6 circuits next to the main. The existing wires (old BX, some going back to the late 1920s, some to the 1960s) are almost certainly too short to work in a new 200A box. If I don't use the old box as a junction box, I'd just have to mount another large junction box (or several smaller ones) in its place. There's no way I'm going to pull new cable for all these circuits.
Though I CAN be down for a while, running on a generator, I'd rather not be. I was thinking that a plan would be to get the new box & meter pan installed with just a couple of utility outlets nearby. Then I could have the power company come and switch the service over to the new meter, then I could backfeed from the new box to the old box.
At that point, the house is powered, and I can proceed with extending the circuits to the new panel, one at a time. When all that's done, I'll remove the backfeed and take out the guts of the old box and screw its door shut. At that point, I can start adding the new circuits I need.
Does that sound like an OK plan?
Now, my question: When extending the circuits from the old box to the new one, do I also extend the individual ground wires, or can I leave them on the bus bar and rely on the conduit (actually, in all likelihood, this will be two or three 1" or so nipples) to continue the ground?
In the end, it's going to be up to the electrician, but I want to go into this with a good starting point for discussion.
Yup. Probably the easiest way. and fastest to get everything repowered temporarily. Probably good, in particular, for do-it-yourself.
Nice information you got from your inspector.
If there is room for the new service wire feed, the new panel can be placed where the old one is, with the old circuit wires coming into the top of the new panel. If the old circuits are BX and Romex it is relatively easy. If EMT, lining up holes can be a pain. It is longer time until everything is refed. The electrician may rather do it this way.
It would be code compliant. I would rather add a wire, maybe #6. I believe if all the circuit wires were #12 or smaller and you connected the panels with PVC. the NEC would only require a single #12 ground wire to the old panel - probably would be a good way to make the inspector unhappy.
Many wires in conduit requires derating of the wire ampacity. If the pipes are 2' or less in length derating is not required. Since you called them nipples you are probably know that.
Since the electrician is pulling the permit, he may not want you doing some of the work. Helping, or even watching. is a great way to learn. I think I may have driven some tradesmen crazy.
I always like to know what the considerations are before talking to someone who will do any work.
No, the wires are NOT alkways too short, if you remove the old panel and replace it with a new panel, in the same place. I've done it numerous times. I've only ever had one or two wires that could not be made to reach in the new panel, in all the panels I've replaced. And by "made to reach" I don't mean stretched across the corner or anything. Always looked professionally done when finished. On occaision it meant using the bottom couple of breakers, along with all the rest closer to the top of the panel instead of all bunched together. When I finally replace my fuse panel, the stove and dryer breakers will be at the bottom of the panel, because that's where the
Just a couple questions - do all the cables come in one side of the
100 amp panel, or do they come in both sides? Most FPE integrated entry panels do not allow cable entry from the service side - so I'd assume yours all come in either top, bottom, or right side (most FPE integrated panels have the main on the left).
If this is the case, simply move the panel 6 inches to the right, and every cable will be lots long enough to fit. If the cables are bottom entry you may need to use the lower breaker positions for those wires.
And for the other guys - why would using a suspect panel (the FPE) which he is replacing due to percieved safety issues as a sub panel be any kind of a sensible move???.
ANd the 200 amp panel will have plenty of space for existing plus additional circuits. The "sub panel" wouls shout "mickey mouse" to the next buyer or their home inspector.
If you're gonna do the job - not only DO it right, but make it LOOK right too.
I have only seen the aftermath of water infiltration to a 277Y480 panel used for lighting when water from a fire sprinkler discharge got into a panel and blew it up, the water dripped in just right to make perfectly round holes in several of the breakers... Looked like a bullet hole from a .22LR... All because of a 3/4" KO that was left open after a circuit and its conduit was removed and no one double checked at the time that the panel enclosure was patched with a metal plate or KO closure...
For want of an item worth a couple of dollars a $10,000 emergency repair, partial rewire and cleanup was required...
There is no legitimate reason to disturb wiring from the 1920's or
1960's unless you absolutely have to do so... You could find that the wiring has not aged gracefully and could require replacing the homerun to the panel for several circuits if the wires become damaged when you remove them from the old panel and insert them into the new panel in the same location OR try to reroute them to a new panel located adjacent to the old one...
So leaving them in place and using the old panel as a junction box after it has been gutted is the best most efficient way to deal with the situation the OP has described...
That is EXACTLY what I was thinking. I recently did some wiring in my kitchen ceiling, and the condition of the old wire was a little scary. You can move it a bit without cracking the insulation, but it would be better to leave it where it is. I replaced the stuff in that ceiling, as I was redoing all the plumbing above it anyway, but I really don't want to do the whole house,
I agree If it looks right, it probably is right. But:
1) This panel has the main at the top. Most of the wires are fed from the top, but some are from the left. It's conceivable that I could pull out the old box and put a new one in its place, but doing so would involve flexing those old cables a lot, and that scares me. I did some work in the kitchen recently, and while the old wire wasn't exactly crumbling, it wasn't very flexible, either.
2) Using the old box as a junction box and mounting the new one next to it won't look any worse than what's already there. This is an old house, and it's never going to be a new house without ripping out ALL the wires and starting over from scratch, and that is simply not going to happen.
More important to me, at this time, is to do a good, safe job, and to have room in the new panel to add a half-dozen or so circuits which are sorely needed. While the walls were open for plumbing work, I ran a piece of 6/3 up to the attic so that I can (later) put a sub panel there to feed some new outlets in the second-floor bedrooms. The old panel is full. I need a bigger one just to have a place to connect that 6/3, if for no other reason.
Then using it as a junction box makes some sense - ASSUMING the wire is not deteriorated enough that simplu moving it in the enclosure causes the insulation to flake off- - - - - - - .
Given that update - go for using the existing panel (gutted) as a junction box
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