Quick Subpanel Question

[pharper]

We recently purchased a new house and I will be converting the 20x20 garage into a workshop for woodworking. I would like to put a 100a subpanel in the garage right next to the main service. The main is 150a. Is there any reason this wouldn't work. I will have a certified electrician do the work for the panel, but thought I'd ask here before getting quotes. How much should I expect to pay? I'd expect this to be about as simple as it gets for a sub panel.

I should also add that the most I'll ever be pulling from the sub would be about 50a (cyclone dust collector, jointer-planer, mini-split.)

 

[theoldwizard1]

Assuming you live in the US, if the new panel is going to be next to the main it does NOT require a main breaker. Buy a panel that has plenty of slots ! The breaker in your main and the size of the wire to the sub will be your limits.

Adding a lot of receptacles to a "finished" room will require a lot wall board to be removed, replaced and patched. You should consider a surface mounted breaker panel and conduit to your outlets.

 

[pharper]

Assuming you live in the US, if the new panel is going to be next to the main it does NOT require a main breaker. Buy a panel that has plenty of slots ! The breaker in your main and the size of the wire to the sub will be your limits.

Adding a lot of receptacles to a "finished" room will require a lot wall board to be removed, replaced and patched. You should consider a surface mounted breaker panel and conduit to your outlets.

Thanks. I already plan to tear out the drywall on both side walls. I will be installing insulation, a window or two, and an exterior door.

Any reason I couldn't install a 100a sub panel with just 150a main service? How much should I expect to pay for such a job?

 

[ForceFed70]

No reason why you cannot have a 100A sub off of a 150Main.

I do question the need for a 100A panel in a 20x20 garage. But with it being so close to the main panel it won't increase price much from say a 50A panel so no harm done I guess.

Something to consider - have you investigated options for adding more circuits to your main panel? Most modern panels can support dual breakers (forget the proper name) that are basically 2 breakers in 1 slot. If your panel supports it, you can basically double the number of circuits coming into the panel and avoid putting in a subpanel completely.

 

[Norcal]

One thing I always recommend is to keep the sub the same make as the existing panel since it seems to be a GE, it be poor practice to use another make unless it was a obsolete one, which is not the case with GE.

 

[pharper]

ForceFed70, I'll need a 20a circuit for AC, 20a for tablesaw, and 30a for jointer/planer. I figured with lights and a couple of 110 circuits, I'd want 100a. Also, I like the idea of being able to add circuits without disrupting power to the house.

Norcal, thanks. I will keep that in mind.

 

[ForceFed70]

ForceFed70, I'll need a 20a circuit for AC, 20a for tablesaw, and 30a for jointer/planer. I figured with lights and a couple of 110 circuits, I'd want 100a. Also, I like the idea of being able to add circuits without disrupting power to the house.

Norcal, thanks. I will keep that in mind.

As I mentioned earlier - it doesn't really matter anyway. But I did want to point out that load calculations aren't done by just adding up the circuits. There is a bit of a formula. Rarely do you use the entire circuit's capacity when in use and rarely do you use everything at once. For example - probably never run your tablesaw and joiner at the same time.

Adding circuits without turning off power to the house. OK - sure I guess. Just thinking back to when I put my panel in. 4 years ago now and I haven't added a circuit yet. When you do add a circuit it's only about 15min of power outage. Do you really think this will be all that beneficial? Worth the $500 it's going to cost you? Personally I'd think you could spend that money on something you'd get more benefit from like tools or a heater or something.

 

[wyliesdiesels]

Why are u putting in a subpanel?

Is your main panel full?

 

[sands35]

I'd think 60A would be more than enough. 6-3 wire makes it easy. You won't be using every tool all the time. Also, can you wire 240 for the fixed equipment? You get to side step GFCI and TR requirements for the garage and then not worry about popping a breaker. Bigger table saws and jointers can be marginal on a 120 circuit.

 

[pharper]

As I mentioned earlier - it doesn't really matter anyway. But I did want to point out that load calculations aren't done by just adding up the circuits. There is a bit of a formula. Rarely do you use the entire circuit's capacity when in use and rarely do you use everything at once. For example - probably never run your tablesaw and joiner at the same time.

Adding circuits without turning off power to the house. OK - sure I guess. Just thinking back to when I put my panel in. 4 years ago now and I haven't added a circuit yet. When you do add a circuit it's only about 15min of power outage. Do you really think this will be all that beneficial? Worth the $500 it's going to cost you? Personally I'd think you could spend that money on something you'd get more benefit from like tools or a heater or something.

Good points. The heaviest load would be running the jointer (30a), dust-collector (20a), and AC (20a). I'd also have some fluorescent or led lights on as well.

The other reason is a lack of space in the current box. I'll be adding 2 x 20a 110v general use circuits, 1 x circuit for lights, and 3 x 220v circuits.

 

[pharper]

Why are u putting in a subpanel?

Is your main panel full?

Fairly close to full. I'm planning on 1 circuit for lights, 2-3 general use 110 circuits, and 3 dedicated 220v circuits.

 

[pharper]

I'd think 60A would be more than enough. 6-3 wire makes it easy. You won't be using every tool all the time. Also, can you wire 240 for the fixed equipment? You get to side step GFCI and TR requirements for the garage and then not worry about popping a breaker. Bigger table saws and jointers can be marginal on a 120 circuit.

60a might work. I guess I'd take the advice of whatever electrician does the work. I'll be doing 240 for my tablesaw, jointer/planer, dust collector, and AC. Only planning on 2-3 general use 110 circuits. I'm guessing I can protect those circuits with a single gfci outlet, correct?

 

[pharper]

I found a picture I had taken of the inside of the existing box. There's a bit more room than I thought.

 

[checkthisout]

I found a picture I had taken of the inside of the existing box. There's a bit more room than I thought.

You got all the room in the world there. No need to mess with getting a subpanel.

Now, send Wylies and Forcefed a commission check. They just saved you $500.00 bucks!!

 

[pharper]

You got all the room in the world there. No need to mess with getting a subpanel.

Now, send Wylies and Forcefed a commission check. They just saved you $500.00 bucks!!

Glad they were able to talk some sense into me.

 

[ForceFed70]

I found a picture I had taken of the inside of the existing box. There's a bit more room than I thought.

That's LOTS of room. Use double density breakers for your new circuits and you'll still have a bunch of free slots for future use.

 

[pharper]

Thanks everyone. Very helpful!

 

[theoldwizard1]

I counted 13 empty slots. Plenty of space, especially if you install a couple of tandem breakers.

 

[BDT/NWMN]

Thinking I would take the money planned for the subpanel; and apply it toward some led lights...... give Platonic Solid a buzz for some expert advice on led lighting..