When you're planning the wiring for you basement keep in mind that you may need to install a sub-panel. How much will it cost? Should you install it yourself? What should you buy? Do you really need one?
Lucky for you, you have a friend who's finished a basement before... me! In this post I'll go over what I did and why I made the decisions I made.
An electrical sub-panel is basically an extension of your primary electrical panel. Or as I like to call it, the "main" panel.
If you're adding new electrical circuits to your basement (lights and plugs) then you may not have enough slots on your main panel to hook them all up.
You probably have enough power, just not enough room.
When I was finishing my basement I really wasn’t sure if I needed a sub-panel or not. Well, actually I was sure I needed one but I didn't want to admit that I did because that meant I would have to spend more money. It wasn't as bad as I thought though.
For the first couple of weeks I just extended some existing circuits instead of hooking up new ones.
You know those 2 or 3 little pull-chain lights, yea those, I just added on to that circuit. It's a lot easier than you might think. With LED light bulbs you could actually add quite a few lights on a single circuit and not risk overloading it.
Plugs however are a different story. I knew once I started designing the electrical for the plugs circuits that I would need to get a sub-panel.
How to Install a Sub-Panel
Unless you’re a true licensed electrician, I'm going to say strongly that "YOU DON’T". Leave this one to the pros. You are talking about a lot of juice and some different wiring and safety requirements than just hooking up a circuit or two.
It's not that I didn't look around and investigate how to do it. You know me, I'm Felix Fix-it up in here. I did find some half-way decent instructions on what to do. BUT… I'm not about to take a risk like that just to potentially save a few bucks. Plus I didn't really want to spend an entire weekend or two figuring it out.
Hire someone. Call a local contractor. I think I paid about $500 for him to install the sub-panel in my basement. That included the actual sub-panel box, a bit of framing to hold the box and he even hooked up 3 of the circuits that I had already run and left hanging where the panel would go.
Sizing Your Sub-Panel
One thing I wish I had done was size it just a bit bigger. We also want it bigger, don’t we. My sub-panel is 125 amps, I probably should have gone to 200 or 240 amps.
I didn't run out of room yet but a bit more future proofing would have been prudent. I hooked up 3 light circuits and 2 plug circuits, including the GFI circuit for the bathroom.
Benefits of a Sub-Panel
There's the obvious benefit of having the extra slots. You can also turn off all of the power to your sub-panel from the main panel. Once it's off you can safely hook up your new circuits on your own.
That's right baby! I went to the D' Po and picked up a couple of 20 AMP breakers, installed them into the panel and then hooked up the lines myself. (Or you could order some from Amazon, here's what I used. )
I powered the sub-panel back up and viola, power to the people!
I kind of consider that moment the pinnacle of teaching myself how to do electrical, awesome feeling!
Once I knew I could do that whenever I needed to I had a lot more flexibility in how I designed my other circuits. Knowing I could hook it up myself definitely speed things up and made the design simpler.
The Bottom Line
You can start without a sub-panel, especially for light circuits, if you're not quite ready to do it. But I highly recommend installing a sub-panel, especially if you're adding a lot of outlets, a bathroom or a big energy device like a treadmill or an entertainment center stuff.
Hire a professional. It will only take about 3 hours to install and shouldn't cost you too much in the scheme of things.
Are you doing your own electrical for your finished basement?
Did you or do you plan to install a sub-panel? Let us know in the comments below. Or leave a question if you have one.
Cheers - Jason
- Check out the basement electrical page for a list of articles.
- Do you want to finish your own basement? This is the book for you.
- Here are some great basement ideas, each custom wrapped for you!
What size is your main panel? 200A? I'm assuming that if you're starting with a 100 Amp main panel, you wouldn't be able to install another 100 Amp sub panel, correct?
Yes, that's correct. I believe my main is 200. - Jason
Do I need to hire a inspector to see that I did everything right
Hi Tony - Yes! IF you installed you're own sub-panel (which I personally do not recommend but it is possible) then you should absolutely have it permitted and inspected. Good luck! - Jason
I have a 200amp service coming in my house with the main fuse box on the main floor in the laundry room. I want to put a sub panel in my basement, directly under the main panel. about 6 to 8 feet of wire between the two. I'm confused on what amp to make the sub panel. What size breaker would I use in the main panel (one breaker or two) and what size wire would run between the two. I believe I will hire an electrician to do this but just want to make sure that when I am talking to them that I sound more educated.
Hi Rick - These are great questions to ask the electrician - they will definitely have some recommendations. If you ask just like you have here - you'll sound like you know what you're talking about. Good luck! - Jason
Can I run 2/0 aluminum cable from the extra lugs in my 200 amp square D panel to another 100 amp square D panel
Main CB panel connected to grid feed by 2 each 100 amp breakers with all slots filled with quad breakers including two 40 amp breakers from Solar panel apparatus. I want to convert to all electrical house eliminating natural gas appliances for climate change reasons. I want to move the solar breakers to a sub panel and replace in the slots vacated from moving the solar breakers new beakers to feed to the sub panel. Sub panel will have the two 40 amp breakers for the solar, two 50 breakers for stove, two 40 breakers for a tankless water heater, two 30 breakers for clothes dryer and two 20 breakers each for one or two electric wall heaters. My question is what size breakers should I use to feed to the sub panel?