How many 1" breakers do I really need?

[Jim O'Dell]

I'm sitting here rethinking this load center thing. How many slots for 1" breakers do I really need? My main shop is 24 X 20, with a separate 10 X 14 room I'll use for finishing, maybe assembly. For 220 circuits, I'm planning 1 for each of the following...table saw, cyclone, compressor, ac/heat unit for finish room (when it doubles as a dog quarantine room), bandsaw, drill press, future jointer, and one for the welder my dad turned over to me. That's 8 slots. Then for 110 circuits for lights, wall plugs, and the spot for the lunch box planer, say I really divide that up and used 7 circuits, that's only 15 spots total. Surely a load center that will accept 20 full size breakers will be enough, or am I missing something???
How many slots do you currently use, and how many free slots are available for future use??? Thanks! Jim.

[Mark Aho]

I'm not an electrician, but I've done a bit of my own wiring, and as far as I know, all 220V breakers are double pole meaning they are twice as big as a 110 breaker (they take 2 slots). This is because they get power from both of the hot service lines (each are 110 and together that makes 220).

That means your (8) 220 circuits would need 16 slots in the box.

I'm not sure on the exact terminology, and I'm sure someone else will fill you in better.

[Jim O'Dell]

Mark, thanks. I knew that! Must be that I'm so full from dinner out at Ginger Bown's tonight. So 16 plus 7 puts me over the limit for a 20 slot unit, 30 might be ok. Might still be best to go for the 40 slot unit... who knows, maybe I'll light up the creek behind the house! Thanks for the gentle 2X4 slap! Jim.

[Mark Aho]

No problem, I just happened to be thinking about wiring when I saw your post. I am filling my main breaker box a lot faster than I thought I would and am quickly running out of room. I am going to have to add a sub-panel (or two) just to meet my needs. (This is for my whole house not just a shop).

So......I suggest you go with a 30 slot at least, because it's a lot better to have slots you may not use right away (or ever) than to not have enough slots and have to start playing around with subs or changing boxes.

[Tim Morton]

Jim, you might want to think along the lines of sharing some of those circuits. I do not think you need a sperate 220 circuit for each of those 8 tools unless you think you will be running them all at the same time. Search out Frank's shop thread...he had alot of great info on electrical layout. You should be able to whittle that down to 4 without comprimising anything.

[Jim O'Dell]

Jim, you might want to think along the lines of sharing some of those circuits. I do not think you need a sperate 220 circuit for each of those 8 tools unless you think you will be running them all at the same time. Search out Frank's shop thread...he had alot of great info on electrical layout. You should be able to whittle that down to 4 without comprimising anything.

Tim, I had thought about that, but I happened into most of a bulk roll of 10/3 with ground at 75% off HD's regular price when they were closing out a store from a relocation. So I have the wire cheap, boxes and receptacles won't change, it's just the price of the breakers, so I figure, why not, just go ahead and do separate runs. I understand that you don't daisy chain 230 circuits, but have to go to a junction box, and route from there. So this saves me the junction box, and trying to work this huge wire into them, join 3 sets of wires, etc, etc. I think the frustration factor alone would more than offset the price of the extra breakers!! ;-)) The cyclone, compressor and AC/Heat unit will all be within 10' of the load center. 2 will be in the ceiling, and the other 3 spaced out down 1 wall. The interior is completely gutted, so it's easier to run the wiring (like 10/3 w/gnd is going to be easy to run!) I tend to do things as overkill as I can given the money available at the time, and what deals pop up in front of me. It's just my nature. Drives the LOML batty. Jim

[jack duren]

you can tie a few tools together like a planer and a tablesaw or RAS. the only good thing about separating and using more breakers is the ability to tie in to an existing outlet with another tool,light,etc in the future without concern of overloading.

a dust collector,saw,compressor,lights,heater,radio,etc can eat alot of amps at one time.....jack

[Steve Stube]

Jim, I'm not sure if we share the same meaning of daisychain.

I understand that you don't daisy chain 230 circuits, but have to go to a junction box, and route from there.

You can surly have multiple outlets on a 220V circuit if you use pigtails at the receptacle box (junction box). If you prefer separate circuits that is fine too. I may not understand you - is it making up the pigtails that is the source of frustration?

[Randy Meijer]

..... it's just the price of the breakers, so I figure, why not, just go ahead and do separate runs.....

I don't know what your local code says about GFCIs; but breakers with built in GFCIs can be a little more costly. Something you might at least think about a little bit.

[Steve Cox]

Since I just did a full re-wiring job I'll share my experience. My main panel is in the garage/shop and I put a 100A sub right next to it. In the main panel I have seperate circuits for the lights (110V 20A), heater (220V 30A), and I left the garage door on its' original circuit. All existing outlets in the garage were blanked off, the two GFCIs were replaced with ones that don't have any receptacles. All new outlets were run out of the sub-panel. This means when I leave the shop at night I can turn off and lock the sub-panel which means no one can turn on any tools but I still have lights, heat, and the door works. I have two very small children and this seemed like an important safety feature to me. As far as the circuits go, I have 220V circuits for the compressor, cyclone, tablesaw, bandsaw, jointer, planer, plus two extras for future use (shaper and edge sander?). All of these are 20A circuits using 12/2 wire which means you will have heavier wire and an extra one as most 220V tools in our shops don't require a neutral wire. I only have two 115V 20A circuits and this has been more than adequate for me so far. The lathe, drill press, drum sander, and spindle sander are the only 115V tools that I have and only the drum sander comes close to needing its' own circuit but it's not used enough to justify it. The two 115V circuits are arranged so that they alternate around the perimeter of the room so if you plug into two adjacent outlets you are on seperate circuits. If you count all that up I am using 16 slots for 220V and two slots for 115V. So 20 is adequate for me. Long post I realize but I thought I'd throw some of my info out there to help you think about your needs and wants. Good Luck!!!

[Tony Falotico]

Jim, I wired in six 220V circuits, but until now have only connected two. The others are there, wire in the wall from receptacle box to load center. If and when I need one, all I have to do is add receptacle in existing wall box and breaker in load center.

To answer you question, I have 20 slots in my panel box in a 20' x 28' shop, 11 are used, nine are spares. If I hook up the other four 220 circuits, I'll only have one slot left. For the lighting circuits I used the double 15 amp 120V breakers, so I have two breaker slots used for three circuits, one is empty. I definitely wouldn't go less than 20, probably 24 - 30 if I were to do it over again.

[Jim O'Dell]

Jim, I'm not sure if we share the same meaning of daisychain.



You can surly have multiple outlets on a 220V circuit if you use pigtails at the receptacle box (junction box). If you prefer separate circuits that is fine too. I may not understand you - is it making up the pigtails that is the source of frustration?

Steve S., I think the frustration would come in trying to tie 3 pieces of 10 guage solid strand wire, 4 wires each, inside a box. Especially one that also has an electrical receptacal in it. Possibly a pro can do that, but I have enough trouble doing it with 14 guage solid wire, on a 110 circuit!! Does this make more sense?

Steve C., I agree with how you separated the power for safety sake with the kids. The only little ones we have are 4 leggers, and while we think they are pretty smart, I think a locked door to the detached shop will be safe for them Big Grin

Randy, I'm thinking about using the GFCI outlets instead. Correct me if I'm wrong, but I seem to remember that if a GFCI outlet is the first in the chain of outlets, that all are GFCI covered?? If this isn't true, I may have to rethink the breaker issue. Also, a question on code....I live in an uncorporated area, at least so far. Anyone know who I would contact for what codes I should be following? Just use NEC?? Who do I call for electrical inspection before I can have power hooked back up?

Thanks Tony, I think that solidifies the need for more than 20 slots. 30 would probably work great, but it seems they are harder to find than 40, although there are some that are 30/40.

Thanks for all the great input. I REALLY appreciate the info and help. Jim.

[Mike Mayer]

Consider conduit: One advantage is that you can run #10 stranded wire for 30A circuits. Much easier to deal with than solid wire. You can use ENT (blue plastic) or EMT (metal). ENT is easier to pull through holes in studs and works well if enclosed in walls. If you run multiple circuits in one conduit they can all share a ground wire, so you save on wire. It is also easier to share neutrals on 120V circuits. You don't have the mass of wire entering the panel if you have multiple circuits in each run of conduit.

[Jim Becker]

The cost difference between a "full size" panel and a smaller one isn't great in the whole scheme of things and you also have plenty of room to work inside, too. I have a 200 amp panel in my shop building that replaced a small, 100 amp panel. (that originally was supplied with inadequate 50 amps on too-small wire) It's been a pleasure working in the larger panel from time to time as the shop evolves.

The idea of sharing 240v circuits is valid if you choose to do it and work with combinations that make sense. I perfer to use a j-box for sharing, however, as it's easier to make changes over time if outlets get relocated. Further, the 240v recepticals are fairly large and doing the splicing in a j-box is easier, IMHO. I have some shared outlets and some dedicated in my shop...about 5 240v circuits in all.

[jack duren]

a 100 amp breaker box is sufficient in most cases. i run a business off the 100 amp box and doubt ill fill the box. plenty room.

on a seperate building with a 200 amp box i would drop a separate meter in....jack