I'm running a 100 amp sub panel from my 200 amp main. I have my disconnect breaker for the main 200 amp panel outside in a combination electric meter socket and breaker panel. There is the A/C being fed from here and the 200 amp disconnect breaker for the the main panel.

My question is there are about 12 extra slots in this panel can I put my 100 amp disconnect breaker in this panel. It would be so much easier and and closer to the shed Im running the 100 amp line to.

Any help on this matter will be greatly appreciated..

  • Where is the neutral-ground connection made? (there should be only one place). Mar 14, 2018 at 16:57
  • This raises a good question for us laypeople... what is the practical limit to breaker size on a typical panel bus (aside from manufacturer-imposed limits)?
    – isherwood
    Mar 14, 2018 at 18:22
  • If you haven't already bought it, why not use a 200 A subpanel?
    – Hari
    Mar 14, 2018 at 18:57
  • @Harper I know there are 125 a DP breakers for some panels but most top out at 100a (residential) for commercial panels I have quite a few in the 800 A range (we stop at 800 so we don't have to up size the wire that is required for 800 and above.
    – Ed Beal
    Mar 14, 2018 at 19:22
  • 200 amp panel a bit much for a shed and a hot tub,there will be no major tools or appliances operating in shed @Hari Ganti..believe the neutral and ground connections are made in this panel not the one in house.. Mar 14, 2018 at 21:12

2 Answers 2

  • Can you add a 100 amp breaker to your main panel?

      Yes you have 12 slots the double pole breaker will only take 2 slots.
  • Will you have enough ampacity to run everything with the new sub panel?

There is not enough information to answer fully but probably.

  1. What are your other loads for the home?

  2. Do you have gas or electric appliances / heat?

    If your major appliances are gas (water heater, oven & furnace) I would expect there to be more than enough to run a 100 amp sub, if your appliances are all electric you may have enough but the size of the home would also be needed to calculate your current demand.

  • Hello Ed< my home is 2400 sq ft. under air, my water heater ,stove, dryer, are all electric. hope this helps.. Mar 14, 2018 at 17:24
  • its a 4 bedroom, 3 bath. Mar 14, 2018 at 17:33
  • also from the meter panel to the shed is about 35ft. lug to lug Mar 14, 2018 at 17:51
  • Eddie, please add new information to your question so everyone sees it.
    – isherwood
    Mar 14, 2018 at 18:21
  • isherwood new to this site,am still trying to learn my way around..Is there a specific buttom to hit so it can be shared, thought it was being shared ,,Thanks Mar 14, 2018 at 20:28

Of course you can, you can add the 100 amp breaker to your 200 amp as long as it isn't overloaded, to start adding the subpanel you must first calculate how many yards it will be from the main panel to the subpanel, there is a formula that calculates how much friction will be on the wire at the connecting distance, then you can look at a wire chart and choose the wire size that will best handle the resistance. Once this has been decided , depending on distance, you must figure where you will put this wire, are you putting it in the ground, if so you will have to protect it with conduit, and depending on how much and how heavy the the traffic that will cross the wires will be, if cars and trucks are to cross this area, it would be wise to get the proper conduit, or risk having to dig it all up because of broken wires. If the wire will be air bound you must make sure it will be out reach, to anything. Once all this has been established, you can now bring your sub panel in, you must then calculate the amount of constant amprage that will run through this box, it is best if the constant amprage falls short of the total amprage by at least 20 amps. Wires tend to heat up when the amprage is raised. All that is left to do now, is connect it all together to complete the curcuit.

  • Oh, forgot to mention, in order for it stand to code, the conduit must be buried at least 18 inches in the ground, the conductor t is usually PVC and it must be able to handle what kind of traffic that will be crossing it. In high and heavy traffic area's I suggest, PVC that will stand to code. It is no fun having to dig up and redo all that you have done.
    – user93518
    Nov 26, 2018 at 18:22

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