Q&A for How to Add a Subpanel

The most common sub panel that you'll see out there is the 2040, usually at 60 amps.

You have to do a load calculation for the room you're going to power. This involves calculating how much amperage and voltage you're going to be using, based on the number of circuits you're going to have.

A subpanel is a smaller service panel that serves as a “middleman” between the main service panel and other branch circuits throughout a home or other building. It’s useful way to separate out electrical service between different parts of a building. For instance, you might create separate subpanels to control the power for the different units in a duplex.

It depends on where you live. Contact your local building and codes department to find out if you need any sort of permit to do the work.

If you do it yourself, you’ll only need to pay for the materials. A new subpanel may cost anywhere from around $100-$220, but you’ll likely also need to buy a new meter, which can cost up to $500. If you get the subpanel installed professionally, it will cost a lot more (about $1,200 on average).

A residential panel should always consist of two 110V connections of opposite phase (the "hots") plus a neutral connection. If you put a 110 breaker in either the main panel or subpanel, you'll get a branch circuit using just one of the hots plus the neutral, so you get 110V.

A sub-panel box -- if wired with the proper gauge wire and protected with the correct breakers -- can be any size that covers the amps that its rated for and protected against.

It will be a 30 amp 220 volt, if you catch each hot leg, but code requires using one double-pole 30 amp breaker to do that, and you still need to connect the neutral and ground between the panels (four wires in total: 2-hot, 1-neutral, 1-ground).

Call an electrician. It could be a miswired hot wire, or a back feeding neutral. Or someone could have used white insulation wire for running a hot wire and not identified it and then added to the neutral bar. Use a meter and be careful.

Yes. The ground and neutral wires are only connected in one place, the main breaker panel.

The size of the wire will be determined by the amperage rating of the box. For example, #14 wire - 1 amp; #12 wire - 20 amp; #10 wire - 30 amp; #8 wire - 40 amp; #6 wire - 60 amp, and so on.

As long as the amps in the sub panel do not exceed 60 amps when in use, any up to 60 amp breaker.

You could use a 20 amp fuse instead of a 30 amp, you just cannot use a 40 amp fuse or two 20 amp fuses.

You would need to contact your power company, and discuss a new meter with them. You shouldn't have two meters for a single system.

You will need to install a translation coupler on the breaker box first. Then you need to find a doppler ring of the correct size to convert the AC for charging up the grid. Maximum coupling pressure should never be exceeded. The dryer circuit will run any dryer made in the USA. Be sure to ground them all first. If you will be using gentle cycle on the dryer, be sure to switch the odd breakers to the off position while drying.

Placing end of the new wire and the old wire in a junction box and connecting them with a properly sized wire nut would be the best method.

Yes, the subpanel can have the same size breaker as the main panel, but never larger. You can save the cost of a 2 pole breaker by installing a "Main Lug Only:" type sub panel. It will have a lug on each of the two hot buss bars on to which the breaker will connect - instead of feeding through the 60A breaker.

Short answer: No. You need 2 pole power for any panel. This is for load balancing and so that 240v breakers can be installed. You can use a panel that is fed with 240v to power multiple 120v breakers, but the panel needs to be supplied with 240v.

The breaker size is determined by needed capacity and wire size. Make sure the wires coming from the breakers are of a sufficient size to handle the load provided through the breaker.

It is no different than on a private circuit. Your usage may be different with and without a subpanel so your sharing partners should be informed based on how the use is paid for.

Yes but with wet locations, you need to use GFI breakers. The well and the pump and the charge might not be able to run ats the same time, depending on the capacity of the sub panel.

If it is otherwise unused and a double pole if you want 240v. If it is in use, you could rewire that load at the sub panel.

You would need to know what 120% of your anticipated current draw will be supplied by your sub-panel to answer that question.