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I'm doing a kitchen remodel and while tearing down the walls I found quite a mess of wires from a sub-panel that exists in a small closet off the kitchen. It was so bad that I decided it needs to be replaced.

While replacing this sub-panel the main feed wires from the main panel down in the basement started to crack along the insulation, they are very old maybe from the 1950's and brittle. I've enclosed some pics of my new sub panel box and the 70amp breaker down in my main panel that feeds the sub-panel. I want to pull this wire because I don't think there's any way this will pass inspection with how brittle the coating is on the wire. I've got electrical tape on the wires now, but that isn't gonna make it pass either.

My question is, what size wire can I replace this with? It's a 70amp breaker down in the basement, and the wire that's there now is quite large, maybe a 2 gauge. I believe this might have been a main box back in the day and this wire used to be a main into the house and not a sub, instead of rewiring, they kept it? Just my opinion.

My sub panel will be used to power electric stove, oven, microwave, refrigerator, dishwasher & sink disposal along with lights, outlets and other lights in other rooms in the house. Thank you for any and all help/advice! P.S. This is in New Jersey.

New Sub-Panel Sub-Panel 70amp breaker in Main Panel

  • If you run a 50A electric stove, 15A microwave, and 15A fridge at the same time, you are already over 70A. You might want to consider a more powerful subpanel. – user4302 Aug 17 '16 at 20:31
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For 70 amperes, you'll want to use 4 AWG copper or 3 AWG aluminum conductors. If the run is overly long, you'll want to compensate for voltage drop, by increasing the size of the conductors.

It looks like there originally wasn't an equipment grounding conductor included with the feeder, but you'll need one with the new feeder. If the original feeder was run through conduit, you might have to upgrade the conduit to fit the additional conductor.

If the original feeder was a cable assembly, and not individual conductors run through conduit. You should be able to replace it with 4-4-4-6 cable, from the local big box home improvement store.

When you install the equipment grounding conductor in the new panel, you'll want to make sure the neutral bus bars are isolated from the ground. And you'll have to terminate all the neutral and grounding conductors at the appropriate bus bars.

NOTE:

  • If you're replacing the panel, you might have to install AFCI and GFCI protection devices as required by code.
  • If you don't want to rewire all the circuits in the panel to add a grounding conductor, you might want to consider adding GFCI (and possibly AFCI) protection devices.
  • I picked up 50 feet of 2 AWG aluminum (4 wires: 2 power, 1 neutral, 1 ground) at Home Depot and will use the ground to run from the main panel to the sub panel, prior I think the metal tubing on the old wire was supplying the ground, which I didn't trust that much. Now if I am using 2 AWG and it's a 70 amp breaker is my wire too large for the amps? Should I upgrade the breaker to a 90? – Michael Giusto Aug 18 '16 at 19:26
  • @MichaelGiusto You wire can never be too large for the amperage. There's no problem using 2 AWG aluminum wires on a 70 ampere feeder, as long as the conductors fit within the terminals on the panel. – Tester101 Aug 18 '16 at 20:16
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Since the breaker from the main is 70 amp you will need #4 copper or #3 aluminum. If you use aluminum make sure to pick up some oxide inhibitor. After looking at the photos I think the wiring may pass but I would want a new feeder It appears your main ground wire is the only thing on the ground bus.

While completing the remodel it would be a really good time to upgrade the wiring to the outlets to provide a ground.

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