I am doing a simple service panel load-center replacement in my parent's house.

The service comes into a Square D "main range & four" main fuse panel with 4 60-amp cart fuses, with the four branch circuits off that panel (which run through 30 and 20-amp branch plug fuses) each going to a subpanel. Far as I can tell, the Range fuse runs to the central air conditioner and I believe it also goes to the dryer, as they have gas heating and stove. AFAIK, the four branches are all being powered from the two 60-amp Main fuses. (When I pull the MAin block, everything in the house goes off; when I pull the Range, nothing happens. It's winter here so we're not using the A/C and the dryer obviously isn't on all the time.)

One of the subpanels leads to a four-fuse box leading to separate circuits around the house (appears a 30-amp fuse feeds that subpanel), another leads to a Cutler-Hammer fused switch with dual 20-amp fuses (looks like it goes to the kitchen), and the other two go to circuit breaker panels. One of the circuit breaker panels (the good one) has two 20-amp breakers leading to two clearly distinctive circuits (two wires leading out the bottom of the box, with the main wire off the main-range-four coming into the top). I know that these two circuits go, one each, to two additions of the house that were made at separate times. (Obviously, this system has been upgraded and tacked onto by the contractors they've used...)

The other subpanel completely fell apart, cutting off service to a large part of the house. After pulling the main cart fuses and investigating the boxes I figured out that the box had somehow deteriorated and metal had separated inside the box. (If you pushed on the breaker, power would come back because the little metal pieces that had split would make contact...)

The breaker never had tripped and the fuse leading to the circuit off the main never blew. There's no obvious damage to anything, except that the metal appears deteriorated and split. The subpanel to be replaced only feeds 120 volt service to a single branch circuit - no 240 dual-hots here.

Here's where I'm confused: Whoever previously wired this circuit appears to have placed a circuit breaker on both the hot and the neutral side of the circuit. There are currently two 20-amp breakers installed in the old box. A single wire with white neutral, black hot and copper ground wires leads into the box. The two wires are each connected to a lug for each of the circuit breaker sockets. Off the bottom, the same hot and neutral wires leading to the actual branch circuit are wired to the breakers themselves. The ground wires of both the feed from the main and the wire to the branch were connected to the neutral bus bar, and the ground bus bar was unused. This setup seems to have worked for all this time.......

To make matters worse, the previous worker taped over the white neutral wire leading off the box to the circuit with BLACK electrical tape. (The wire coming from the main into the box is still white.) The only reason I can tell it's a white wire is because there are gaps in the tape and you can clearly see the white wire in the gaps. At first this suggested to me that, possibly, for some reason, there are two branch circuits coming into this box, but that just didn't seen to make any sense, because there's no neutral return wire(s) if that's the case, unless they're hidden somewhere feeding back into the main. (I am going to grab my cont tester and see if the neutral lug on the fuse leads to the neutral wire feeding the box.)

Is this normal practice? Does it in any way impair the safety of the box? I could simply rewire the box to use a single 20-amp breaker and hook the white wires to the neutral bar and the ground wires to the ground bar. Or, I could wire it up exactly as it already is. Which would you guys recommend? Any more testing I should do before wiring the whole thing together?

Thanks a lot for any advice...

-fm

 

If you verified that it is a 120 volt circuit and that white wire is actually a neutral, just take the 2 and just wire nut them together or use the neutral bar in the box. Move the grounds to the ground bar.

I have a feeling this used to be a 240 volt circuit and the wiring was just changed in the main box, not both. Maybe just an oversight, who knows.

 

But, taping the end of the white wire indicates to an electrician it is a "black" wire. It is a normal procedure when old wires are used back, like wirenut1110 said.

 

Oh yeah, I forgot the part about it had been re-identified...didn't want to read it again...lol

 

If the service panel is only 6O amp you should really consider a new larger panel and perhaps reorganizing existing subpanels.

 

I can verify what's going into the box without powering the service up by testing continuity. I do know which fuse feeds the box, and the best test would be to just test continuity across the fuse plug socket and the wires leading to the subpanel. (that is, if I test the center pole of the plug fuse and the hot, and the rim of the plug fuse and the neutral, and get continuity on both, I know this is a 120v circuit)

In that case I'll just wire a single 20 amp breaker and hook the neutrals together on the bus bar and the grounds on the ground bar.

My parents are looking into replacing the main service panel (the main-range-four) with a main breaker panel. Only thing holding them back at the moment is the potential cost, since some older parts of the house AFAIK are still old K&T fabric-sheathed wiring - especially the circuits leading off that 4-fuse subpanel. (The circuits I'm working on are NM, however).

fm