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Answers To Electrical Questions About Using Your Old Panel As A Junction Box and Installing a Sub Panel To A Barn

December 5, 2008

Question mark JIMMY TRINETRA asks:
I am upgrading my electrical service to 200 amps. I installed a new meter box on the exterior and the circuit panel in the kitchen wall. To connect the existing circuits from the old panel to the new one, can I use the old panel as a j-box?

Yes you may. Just remove all of the guts in your old panel. I also recommend going to get a piece of sheet metal to use as a blank cover on your old panel.

However, I do not recommend setting a new panel and using your old one as a junction box. It is usually easier, or at least less time consuming, to just upgrade your old panel and install 1 power supply cable to it verses installing several new cables between your old panel and new one.


James Topps asks:
I have a 200 amp service in my house and i am running power out to my barn. I am using 2-2-4 wire. I put a 100 amp box in my barn. So in turn I bought a 100 amp breaker to put in the 200 amp box in house. Out to the barn I hooked up the 2-2 wire to the 100 amp serve and I put the 4 wire on the neutral bar then I hooked up a bare number 4 copper wire and ran it to two ground rods 8ft deep 7ft apart hopefully this is right so fair . The only problem I have is that I do not know if I have to hook up the two 2-2 wire right directly into the 100 amp breaker in the house because the breaker has two spots to hook wire into. I pretty sure I will put the 4 wire on the neutral ground bars. Also am I supposed to swap wires? I am so confused.

There are a few things wrong here. The first problem is that you do not have enough wires going out to your barn. You should be using 2-2-2-4. You need 2 – hot wires, 1 – neutral wire and 1 ground wire. Right now you are missing a neutral.

The next problem is the grounding. The ground rods only needed to be 6 feet apart and the maximum size wire should be a #6 AWG. However, this can remain as it will work.

I think having the additional conductor will help you with your final terminations. You need to connect the #4 ground wire to the ground bar, the white wire to the neutral bar and the 2 – hot wires to the circuit breaker. This will give you 100 amps at 240 volts in your barn. You also need to ensure that the ground and neutral bars are not connected together in your barn. The neutrals and grounds are permitted to be connected together at the first point of disconnect in your home only.

You are required to pull a permit for this type of project. I highly recommend doing so and getting it inspected upon completion. Your breaker boxes are the first point of safety in your electrical system. If they are not installed properly, then nothing else will work properly or safely either.

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One Response to “Answers To Electrical Questions About Using Your Old Panel As A Junction Box and Installing a Sub Panel To A Barn”

  1. Carolyn Hilton on December 9th, 2008 9:02 am

    I am actually electrical designer by profession but this one has me scratching my head. I have a need to control lighting for a forklift fueling shack where the driver does not have to flip any switches while driving in or out to fuel. The shack is 16’x15′ with 4- 2 T8 lamps (DM) in each for a total load of about 400 watts and about 25 FC. I also need a security light and I have found a 18w fixture for that. I was hoping that this motion sensor/timer would work (DESA SL-5210), it states that it will operate 500 watts but the timer is not something that can be set to 30 minutes nor will it pickup inside the building for movement if I have it mounted on the outside to pickup the incoming lift. Can you shed any light on what I should do here. I am at a loss and I can’t seem to fine anyone with the technical expertise with timers nor motion sensors to help? This is a unique situation for sure, LOL! Would an actually lighting contactor and timer work here if I was to wire everything thru it somehow with another sensor installed inside the shack? The thing with the timer is that it would not be set to a specific time everyday, fueling times will vary so it has to be tied back to the motion sensor some way.