I am in the process of wiring a 125 amp sub panel in my basement right next to my 200 amp main panel. I am wondering what size wire I should use to connect the main panel to the sub panel. The sub panel has 12 open slots but I am only going to use 7. 3 - 15 amps breakers and 4 - 20 amp breakers. I am mainly using the sub panel to power up a sump pump, a fridge, lights and electrical outlets. Also I am wondering what size breakers I should use in my main panel to connect to my sub panel. I really appreciate any advice I can get.

Thanks,

Ryan

 

I would suggest that you use a 60A breaker with #6 copper THHN for the hots and neutral and #10 copper green or bare for the ground.

 

Sounds like you could get by with a 60 amp feed to the sub panel. Are you going to use conduit with single wires or multi-conductor cable from the main panel to the sub panel?

How many sq feet is the basement? What type of equipment will be plugged in to the receptacles?

Which state do you live?

 

Thanks,

I was planning on using 1" or 1.5" conduit with single wires. Is this a good idea? Are Multi conductor cables easier work with?

The basement is about 1000 sq feet. The only things that are going to be pluged into the receptacles are a few lamps, TV, stereo, possible a fan or a small heater.

I live in Michigan.

Thanks the help,

Ryan

 

I really appreciate the help.

Thanks,

Ryan

 

In this case conduit is probably the best solution. It's opinion only but individual conductors are a bit easier, no jacket to strip. The heater should to be on a dedicated 20 amp circuit even if it is a portable.

Note: You will need to add a ground bar to the sub if it doesn't have one. The neutral bar must be isolated from the sub panel. No main breaker is needed in the sub panel because it is in sight of the main panel. but if you have one that is fine.

 

When the panels are side-by-side a conduit nipple between the panels is the ideal solution. Use THHN individual conductors: black or red for the hots, white for the neutral, green or bare for the ground.

The 60A panel should be just fine for that. I too recommend a dedicated circuit for the space heater. Actually, the best solution if you know you need heat would be to install a proper electric baseboard heater and thermostat. They are much safer than portable space heaters.

We are on 2005 code in Michigan, so you will only need AFCI breakers if any of these new circuits are going to bedrooms. Receptacles in the unfinished portion of the basement must have GFCI protection. Hardwired smoke detector(s) may be required depending on your local jurisdiction and type of use of the basement rooms.

 

Question

If I add three more breakers for smokes, the heater, and the GFCI in the bath will the 60A breaker on the main panel, the #6 THHN and the #10 for the ground be good enough?

Thanks,

Ryan

 

It is not unusual for the total amps of the breakers to exceed the maximum supplied amps because some breakers are lightly loaded and some not in use when others are in use. For years a whole house ran on 60 amps so that should be fine for your needs. Of course if you use conduit and individual conductors between main and sub increasing amps in the future, should it be needed, is easy and quick. Sixty amp should be fine for now.

 

Thanks for the help.

Ryan