I have a two domed home. One dome has never been wired and I want to pull 100 amps to it. The main dome has 200 amp service. Can I put a 100 amp breaker (or should it be 2 50 amp) in the main box and run wire to a new breaker box in the second dome? Also is 6/3 with ground heavy enough to carry the power? I had one person at menards tell me to use 3 6ga and 1 4ga wire and another one told me I could use the 6/3 with ground. The 2nd dome will be used as a family room. :confused: Thanks for the help. :p idoitall523

A 100 Amp 120/240 volt feeder for a residential dwelling can be as small as #4 copper THHN/THWN, USE, or SE cable.

#4 copper NM-B cable (Romex) is not allowed.

MC cable will be allowed.

#2 aluminum is also allowed, 4 wire SER cable is widely used for this feeder.

Any feeder will need to be 4 wire, with 2 hots, 1 neutral, and 1 equipment ground.

Do not ever ask a store clerk electrical advice unless they can produce a tradesmen license for the trade they are giving advice for.

#6 copper is good for 55 amps at best.

I suspect, as a possibility, to defend the store clerk, that you thought you need two 50 amp breakers, and the clerk responded with a wire rated for 50 amps.

The circuit breaker will need to be a 2 pole 100 amp.

First of all Thank You for your answer, but I still have a couple of questions and I should have been more specific
The run from one dome to the other dome will be inside the home across the floor joist in the basement.

I believe the #4 copper THHN is a single wire?
If so I'll need 4 wires, will I have to put these in conduit.

I don't think we will ever pull 100 amps but how knows what will happen in the future? With that in mind will #4 wire be heavy enough or should I go to #2 wire if I can get it into the breaker box?

I was also told I'll have to cut the strap between the neutral and ground?

I'm new here so I don't know if this will get to you. Thank you for your time and knowledge.

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You can use conduit, but it usually is difficult to run in wood frame, if that is the cnstruction.

I would use the #2 4 wiree aluminum SER cable.

Protect any large cable or PVC conduit with nail plates where it passes through wood framing, to prevent nails and screws from hitting the cable.

You can use #2 copper THHN /THWN if you like, can affod it, would be a top notch job.

Up to you Code is only minimums and maximums. Doing better than Code is always good. Just with economy as it is, the Code can be your friend. Up to your pocket book. The min #4 has been derated ince residential typically does not draw much. Now if you have a plan and it contains large loads, then the Code minimums may not be large enough. Code allows for "typical".

Yes the neutral must connect to an insulated neutral bar, and the equipment ground connected to a bare bar bolted to the panel box, and neutrals and grounds must be separated.

Cutting the bar may be slang for that. Don't just cut anything yet. Be sure to read the instructions that come with the panel, it will tell you exactly what can be done to this brand of panel to separate the neutral and ground.

You may need to buy an accessory equiment bar.

Conduit THHN - yes.

Distance plays somewhat of a roll.

You normally can't put breakers rated >100 A for a circuit in a panel. Your main breaker for the sub-panel doesn't have to be rated for 100 A. It an be 200 A if you'd like it to be used as a disconnect. It can also be a "main lug" panel with no main breaker.

On the sub, you may need a ground lug kit. There is a screw (usually green) that need to be removed that breakes the neutral ground bond. The ground bar kit gives you terminals to wire the grounds.

If the 2nd dome is a "detached structure then a ground rod is needed.