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

[Jim O'Dell]

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

Jack, this building came already set up this way!! Separate power line from the pole, separate meter. Only bad thing is I won't be able to hide how much electricity I use ;-)).

Jim B., I think I remember you talking about junction boxes in another thread a while back. I had considered that until I got the great deal on the 10-3 w/ground that the local HD had left over when they moved. I got what was left on the roll at 75% off. That's when I decided I had enough wire to do home runs to everything. If I need to double up later, I plan on leaving a little slack where I can cut, install a J box, and split off as needed.

Mike, if I was buying the wire at full price, or anything close to it, I would do just as you suggest. But the wire is here, and it was CHEAP!!

Speaking of cheap, (it's that Scottish blood from my Mom's side of the family), the reason I started questioning how many slots I really need is I started adding up the price of the SD 200 amp box, then adding all the breakers. I'm at about 350 to 400 bucks. I need to go back and look at the GE unit HD has. I did see that it says it has copper bus bars. If it has 30 slots and I can save a bundle, it might be worth it. The load center for the house is a GE...might even be able to swap breakers in a pinch if needed.

one more question if I may...most 220 circuits should be 30 amp I'm guessing. The cyclone is the Clear Vue with the Leeson 5hp (3 hp continuous) motor. I have the MM E 16 Bandsaw with the 2.5 hp motor, plan on a 60 gallon compressor that will be rated at about 13 at 90 psi, hope one day to get a 3 hp cab saw (have a Ridgid 1.5 hp contractor saw now), and 6 or 8" jointer. The drill press may or may not get wired to 220 (Delta 17-965), the PTAC I'll eventually put in might need 40 amp, but probably not. Then there is the welder (small unit) I'm sure 30 amp is adequate for this. Anyone see any flaws in this thinking? Thanks again. Jim

[Steve Cox]

All my 220V circuits are 20A. I am using a Jet 3hp cabinet saw, Powermatic 8" jointer, Rockwell 2hp 13" planer, Laguna 16" bandsaw, CH 60gal compressor, Woodsucker 2hp cyclone, and hope to use a 3hp shaper in the future. All of these run on 20A circuits with no problem.

[Peter Mc Mahon]

Hello Jim. I have a Siemens panel and there are double breakers available for it. It is 2 110 breakers [15amp] that fit into a single space. This effectively doubles all of your 110 spots. Peter

[Randy Meijer]

...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...

Not exactly sure what Steve is telling us; but would like to make the point that "TWO" light circuits would be a prudent move. Should you be right in the middle of a milling process and have the light circuit trip and loose "ALL" of your lighting, it would be a very dangerous situation!!!!! With your lights on 2 different circuits, hopefully you would never be totally in the dark with other machinery still running.

[Randy Meijer]

...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....
Jim:


For 120V outlets, what you are remembering is correct. The GFCI does not have to be the first outlet in the circuit; but if it is not, then only the GFCI outlet and any "downstream outlets" will be protected.


I have never wired any 220V circuits with GFCIs so I can't advise as to specifics. Since GFCIs work by comparing amperage in the hot and neutral legs of the circuit, I don't know how that applies to 220V circuits since you have 2 hot legs and no neutral. You probably need to search out some additional info about GFCIs installed on 220 circuits or maybe some SMC member knows the answer.


Here in Texas, building permits are issued by a county office for construction in unincorporated areas unless you are in the ETJ of a city. I assume your local government has a similar structure. I'm sure that someone in that office could inform you of the necessary requirements. Good luck!!!

[Tony Falotico]

Not exactly sure what Steve is telling us; but would like to make the point that "TWO" light circuits would be a prudent move. Should you be right in the middle of a milling process and have the light circuit trip and loose "ALL" of your lighting, it would be a very dangerous situation!!!!! With your lights on 2 different circuits, hopefully you would never be totally in the dark with other machinery still running.


Agree with Randy on this one, I alternated my lights on two circuits with two separate switches for the reasons Randy stated.

[Jim Becker]

Since GFCIs work by comparing amperage in the hot and neutral legs of the circuit, I don't know how that applies to 220V circuits since you have 2 hot legs and no neutral.

240v GFCI is done at the breaker...there is an extra lead that gets installed in the breaker box.

[Steve Cox]

It seems that many people are installing lights on two circuits but I don't understand why. Yes the idea of lights never going out while milling something is a good idea, but please tell me what would cause the lights to go out. Circuits pop when you have an over current situation. If the lights are on, and the circuit is not permanently overloaded (too many lights) what will cause them to go out? The only thing I can think of is a short in one of the lights or the wire going to it and that is an extremely rare circumstance. I can live with that risk. If there is something that causes the whole panel to blow then whatever tool you're working on will stop as well. The point of the circuit being in the main panel in my original post was that the sub that controls all the outlets could turned off and locked as a safety measure for my kids but the lights and heat still work in the shop.

[Jim O'Dell]

I was watching an e-bay listing on a Square D 30/40 200 amp outdoor box, starting bid placed at 49.99. Figuring it would go up, I was looking to see if anyone else was bidding on it, and found the seller had the same box, but the indoor model starting bid 49.99, buy it now 49.99, so I jumped. These don't come with the main breaker, but I had already e-mailed the seller and he has them for 60.00. Both box and main are new, sealed in the box. I think I did alright. 30 slots should be plenty, and if needed, I could add some 1/2" slots to gain some. I also won a bid the other day for 5 - 220volt, 30 amp breakers (used) for 14.99 total plus shiping, and 6 new leviton 120 volt GFCI for 31.00 plus shipping. Now to find some more breakers, and some regular outlets!!!! Jim.

edit: Where are my manners?? I meant to add that I appreciate all the information passed along to me on this thread. I went back looking for who mentioned e-bay to me, may have been on another thread, and couldn't find you, but THANKS for reminding about this resource. On this one project alone, it has already saved me a bundle!!

[Chris Padilla]

Guys,

If you plan to wire in 120 V GFCI, just remember that in a mulitwire situation (i.e. you bring in 2 hots (red and black) and a neutral (white) and ground (green/bare)), each GFCI needs its own neutral. So in this situation, you would need two neutrals. This nearly bit me but thank goodness I put in mostly flex conduit...wasn't too bad to pull a second neutral.

[Jim O'Dell]

Guys,

If you plan to wire in 120 V GFCI, just remember that in a mulitwire situation (i.e. you bring in 2 hots (red and black) and a neutral (white) and ground (green/bare)), each GFCI needs its own neutral. So in this situation, you would need two neutrals. This nearly bit me but thank goodness I put in mostly flex conduit...wasn't too bad to pull a second neutral.

I'm lost, Chris. Are you talking about multi wiring through a conduit that would do multiple 110v circuits? I plan on running 4 individual 110v circuits for outlets, and a few task lights. 2 separate 110v circuits for the main lighting. I will put 1 GFCI at the start of each 110v circuit so that it protects everything down stream, each circuit should have it's own neutral, using 12/2 with ground for the 110 wiring, right? I doubt that I'll do GFCI for the 220v circuits, seeing that I just purchased 5 220v breakers that are not GFCI :-0. Jim.

[Chris Padilla]

I'm lost, Chris. Are you talking about multi wiring through a conduit that would do multiple 110v circuits?

More or less, that is correct. Say per box, you want two 120 V duplex outlets but you want each outlet on a different breaker or circuit. In a non-GFCI situation, you would just run 4 wires: black, red, neutral, green/bare (any romex XX/3)-->this is known as multi-wiring. However, if you want to GFCI protect both of those circuits, you would need to run TWO neutrals...you can't share the neutral if you want both circuits protected by a GFCI! You would need some romex XX/4 or pull a second neutral through the conduit.

I don't have any GFCI protection on my 240 V stuff either...only 120 V stuff.

[Ken Fitzgerald]

Jim.....Chris is talking about "Edison" wiring 120 v outlets. In my shop 2 120v circuits go down each wall. Everyother outlet is on say "circuit A" and the next outlet is on "circuit B". You can wire this type of arrange by running 2 12-2 circuits or using what referred to as "Edison" circuits using 1 12-3. The problem arises when you try to put GFCI in to protect the circuits. In my case I had suspicians that GFCI's wouldn't operate properly with the Edison wiring so I ran 2 circuits using 2 12-2s and each circuit has the first "outlet" as a GFCI outlet. Chris used the Edison wiring idea and ran a single 10-3 or 12-3. The trouble is that GFCI's measure the current difference between the hot lead and the neutral lead. If the is a measureable difference, the GFCI trips thinking something is taking current to ground and not back through the neutral. With the Edison concept using a single 3 conductor cable to provide 2 circuits, the 2 circuits using a common neutral and therefore the GFCIs see a difference in currents if something is operating on one circuit and not the other.......in other words, the GFCI works properly but the circuit won't if you use the Edison concerpt. Thanks Chris for proving my theory and justifying the increased installation costs :rolleyes: ..........my local inspector advised me to use the Edison concept!

[Jim O'Dell]

Thanks Chris, I thought that is what you meant, but wanted clarification in case I wasn't understanding. Ken, I'm with you, I already planned to wire with separate 12/2 w gnd wiring. I won't have any multiple circuits in one box, so even though I didn't know anything about 'Edison' wiring, I would probably not have gone that direction anyway. But conventional wiring makes easier sense to me. Thanks for the info. This place is always an education. Jim