Wiring a shop: How many circuits?

[NICK BARBOZA]

I'm doing my wiring right now and so far I'm up to nearly 25 circuits.
3ea lighting circuits 15a each 14ga wire. Each circuit is on its own switch. +/-8ea 4bulb t8 fixtures per switch/circuit.
12ea dedicated 240v circuits for larger tools. For all of these I ran 10ga wire even though all but one of the tools are only need 20a for 3hp motors. All of this wiring is rated for 5hp or 30a. (4 of these circuits are for future tool additions)
8ea 120v circuits throughout the shop. I installed alternating circuit quads every 6-8' around the shop at 50" above floor. one circuit will feed receptacles throughout the ceiling for pull downs/air cleaner/etc..
1ea 40a 240v circuit feeds my rotary phase converter. I only have one 3phase tool right now (16" jointer), so i will be running 10-3 from my RPC to that tool location.

Good luck!!
NWB

[Andy McKenzie]

The one thing you don’t say is how big the shop is - square footage would be a bit of a determining factor for some things.

Definitely have the lighting on a separate circuit. I’ve seen too many places where you pop a breaker with a tool and then are left in the dark to boot. Having two lighting circuits may be overkill. What are the chances you’d pop a breaker on a lighting circuit? Particularly with the low draw of T5s, T8s, and LEDs these days compared to old incandescent setups. But depending on size, it may be useful so you don’t have to light everything up if you’re only working on one side.

Alternating circuits for receptacles is something I’ve done and it seems to work well. I share the workshop with my girlfriend and my father is sometimes over, so it is nice to be able to each be doing our own thing without overloading anything. I also put in receptacles every four feet. That way I can pretty much plug something in anywhere in the shop without using an extension cord.

I’ve ended up with more 220V equipment than I had initially planned on. Fortunately, I was fairly liberal with 220V circuits too, so I’m in good shape. My shaper, tablesaw, planer, and dust collector are all 220V.

The only thing I didn’t quite plan on was I ended up with a 110V 20A bandsaw and thickness sander. Fortunately, I had done the receptacles in 10ga, so I could swap the 15A circuit out for 20A.

The garage is just shy of 18'x18'. It also needs to hold two motorcycles, some bicycles, and a few yard tools. It's still going to feel huge, though... right now I've got just under six by six!

I'm absolutely planning to reserve capacity for more tools later... hopefully enough!

[Andy McKenzie]

I'm doing my wiring right now and so far I'm up to nearly 25 circuits.
3ea lighting circuits 15a each 14ga wire. Each circuit is on its own switch. +/-8ea 4bulb t8 fixtures per switch/circuit.
12ea dedicated 240v circuits for larger tools. For all of these I ran 10ga wire even though all but one of the tools are only need 20a for 3hp motors. All of this wiring is rated for 5hp or 30a. (4 of these circuits are for future tool additions)
8ea 120v circuits throughout the shop. I installed alternating circuit quads every 6-8' around the shop at 50" above floor. one circuit will feed receptacles throughout the ceiling for pull downs/air cleaner/etc..
1ea 40a 240v circuit feeds my rotary phase converter. I only have one 3phase tool right now (16" jointer), so i will be running 10-3 from my RPC to that tool location.

Good luck!!
NWB

Right now I can only dream of having the space it sounds like you have! I'm using LED overhead lighting, so it draws very little power... a 15 amp circuit should handle all the lights I need (probably four fixtures) with tons of capacity left over. I think I remember they draw about a third of an amp each, so really a 2 amp circuit would be fine for those.

Even if I had the tools and power, I think I'd have to stack them to fit everything in....

[Jim Dwight]

I think your plan is pretty solid, provided you are fairly confident you will not add a lot of large tools - and it sounds like you do not have the space. I am in my second shop that is an oversized one car garage. The current one is 14x24. The previous one was a little larger but irregular in shape. Both have only two circuits. A 20A for tools and a 15A for lighting. I used fluorescent lights that pull only a few amps so I also ran a few circuits off the light circuit. I ran a small 1 hp DC on that circuit in my prior shop but I sold it. It was too small. And it took up too much space. My table saw pulls 15A (a Ryobi BT3100) and I pretty much like it. If I upgraded it would be to a hybrid that would work on 120V. My experience is that if the blade is correct, clean and sharp, a 15A 120V motor will cut 3.5 inches deep in hardwood. So why do I need more? So I can use the wrong blade?

Anyway, I think two is the minimum and you are going for 3 so I think you will be fine. A 220V may be something I regret but it isn't impossible to add later. My use would be possibly a welder.

My outlets are also 4 feet off the floor with the 15A ones a few inches higher than the 20A ones. 15A outlets also look different than 20A so you can tell them apart. If you have two 20A circuits in the same box, I think you will be fighting wires big time. 12 gauge wire fights pretty well. If you don't put each circuit on the same side of the box, you won't know which circuit is which. Doesn't seem like a great idea to me but I'm sure it can work. I would put the two circuits in their own boxes and arrange one a few inches higher than the other. If you want to plug different tools into each circuit you need to be able to tell them apart. A DC or compressor would be candidates for the second circuit. If you know where they will be you might even just want to run it that way.

I only use one tool at a time and it's only me in the shop. That's why one 20A circuit works for me. But a second would allow a 1.5hp DC which you might want to run with the tools. I use a shop vacuum with an autoswitch that allows the vacuum and tool to be on the same 20A circuit. Shouldn't work but does.

[Andy McKenzie]

I think your plan is pretty solid, provided you are fairly confident you will not add a lot of large tools - and it sounds like you do not have the space. I am in my second shop that is an oversized one car garage. The current one is 14x24. The previous one was a little larger but irregular in shape. Both have only two circuits. A 20A for tools and a 15A for lighting. I used fluorescent lights that pull only a few amps so I also ran a few circuits off the light circuit. I ran a small 1 hp DC on that circuit in my prior shop but I sold it. It was too small. And it took up too much space. My table saw pulls 15A (a Ryobi BT3100) and I pretty much like it. If I upgraded it would be to a hybrid that would work on 120V. My experience is that if the blade is correct, clean and sharp, a 15A 120V motor will cut 3.5 inches deep in hardwood. So why do I need more? So I can use the wrong blade?

Anyway, I think two is the minimum and you are going for 3 so I think you will be fine. A 220V may be something I regret but it isn't impossible to add later. My use would be possibly a welder.

My outlets are also 4 feet off the floor with the 15A ones a few inches higher than the 20A ones. 15A outlets also look different than 20A so you can tell them apart. If you have two 20A circuits in the same box, I think you will be fighting wires big time. 12 gauge wire fights pretty well. If you don't put each circuit on the same side of the box, you won't know which circuit is which. Doesn't seem like a great idea to me but I'm sure it can work. I would put the two circuits in their own boxes and arrange one a few inches higher than the other. If you want to plug different tools into each circuit you need to be able to tell them apart. A DC or compressor would be candidates for the second circuit. If you know where they will be you might even just want to run it that way.

I only use one tool at a time and it's only me in the shop. That's why one 20A circuit works for me. But a second would allow a 1.5hp DC which you might want to run with the tools. I use a shop vacuum with an autoswitch that allows the vacuum and tool to be on the same 20A circuit. Shouldn't work but does.

Thanks. I can imagine adding a tablesaw, though I think it's pretty unlikely. A lunchbox style planer is a lot more likely: thicknessing and resawing are the two tasks I really don't enjoy with hand tools, so a planer and a bandsaw are nice things to have. But I'm certainly not going to have a lot of space, and since it's just me I doubt I'll be able to run more than one machine and a shopvac or dust collector at once... and a pair of 20 amp circuits should handle that just fine.


Thanks again to all... I've definitely got a few more things to think about than I did this morning!

[Mike Jungers]

Hi Andy,

GFCI outlets or breakers are what you're forgetting! In a garage to be code compliant any general usage outlets below 8' need to have GFCI protection, either the outlet itself or a GFCI breaker. If there is also the possibility of ever pulling a car into the garage there is a minimum height above the floor for outlets which I can't remember right now, and my code book is in the truck. Maybe I missed it, but are you doing the work yourself or hiring a licensed electrician? If you're running the branch circuits yourself i have a few things to add.

Anyway, good luck with your new space!

Mike

[Andy McKenzie]

Hi Andy,

GFCI outlets or breakers are what you're forgetting! In a garage to be code compliant any general usage outlets below 8' need to have GFCI protection, either the outlet itself or a GFCI breaker. If there is also the possibility of ever pulling a car into the garage there is a minimum height above the floor for outlets which I can't remember right now, and my code book is in the truck. Maybe I missed it, but are you doing the work yourself or hiring a licensed electrician? If you're running the branch circuits yourself i have a few things to add.

Anyway, good luck with your new space!

Mike

I'm only forgetting to mention the GFCI circuits! I hate that they cost so much more, but I'm really pretty pleased about the "not burning down my garage" and "not killing me" aspects.

I will be doing much of the work myself, and having it checked by someone who knows what they're doing before anything goes live. I've also got pretty thorough instructions on how to make sure I don't have to rip it out and start over, but I'm willing to hear further advice. If I screw up a dresser, I'm out some wood. If I screw up plumbing, I'll have to make repairs. If I screw up electricity, I probably won't know until something is seriously wrong.

[Mike Jungers]

Right on Andy. Then here's a few professional suggestions: From what you've said I would agree that two 20 amp circuits is going to cover it for you. Dollar for dollar, T-5 High Output florescent fixtures give the most light for the money. 4' and 8' fixtures using 54 watt lamps are available at Big Orange. LEDs use less electricity but the budget fixtures can have poor color rendering which can make finishing tricky. Halogen task lights are good for getting color right. As for the branch circuits, use two wire romex (14-2, 12-2) to supply general purpose outlets; sharing a neutral through GFCI's in certain configurations won't work so just use two wire. Yes, GFCI's are a few bucks but you only need the first outlet on a circuit to be GFCI and the regular outlets down stream are protected. When you buy your outlets, go ahead and get 20 amp receptacles instead of 15 amp. They're better made than 15's and with shop equipment you can see 15 amps from a single piece of equipment. Last but not least a 120 volt smoke detector in any shop is a good idea even if you get the occasional false alarm from ripping maple with a dull blade. Not that I've ever done that...

Good on you for getting a second set of eyes on everything once you're done. You don't want to let the smoke out of anything! Good luck.

Mike

[Chris Damm]

My 20x40 shop has 3 lighting circuits, 2 20 amp circuits on each of e walls and one on the wall with the doors. there are also 4 240v circuits for the big stuff. All the 20 amps are 4 gang boxes.

[Andy McKenzie]

Right on Andy. Then here's a few professional suggestions: From what you've said I would agree that two 20 amp circuits is going to cover it for you. Dollar for dollar, T-5 High Output florescent fixtures give the most light for the money. 4' and 8' fixtures using 54 watt lamps are available at Big Orange. LEDs use less electricity but the budget fixtures can have poor color rendering which can make finishing tricky. Halogen task lights are good for getting color right. As for the branch circuits, use two wire romex (14-2, 12-2) to supply general purpose outlets; sharing a neutral through GFCI's in certain configurations won't work so just use two wire. Yes, GFCI's are a few bucks but you only need the first outlet on a circuit to be GFCI and the regular outlets down stream are protected. When you buy your outlets, go ahead and get 20 amp receptacles instead of 15 amp. They're better made than 15's and with shop equipment you can see 15 amps from a single piece of equipment. Last but not least a 120 volt smoke detector in any shop is a good idea even if you get the occasional false alarm from ripping maple with a dull blade. Not that I've ever done that...

Good on you for getting a second set of eyes on everything once you're done. You don't want to let the smoke out of anything! Good luck.

Mike

Thanks again. I wasn't clear the first time... I'm going with GFCI breakers, rather than outlets. There's always the chance an outlet will get covered by a piece of furniture or something leaned on that wall temporarily, but there's no way I'm going to cover the service panel.

Smoke detector is a good call... I may look around to see if I can find something that will signal inside the house if it goes off. Any suggestions? It'd be nice to know if something goes up while I'm not in the shop.

[Jay Larson]

GFCI - I was told that 'any' outlet had to be on a GFCI. Even the ones on the ceiling for lighting. Another thing the inspector wanted was tamper proof outlets.

Not sure if you have to get it inspected, but you may want to ask beforehand. My inspector was actually very helpful, and grateful, when I asked the questions. It saved him a trip or two.

[Chris Padilla]

It is all up to the AHJ: Authority Having Jurisdiction. Neighboring towns could have vastly differently codes they like to follow.

[Thomas Bank]

GFCI - I was told that 'any' outlet had to be on a GFCI. Even the ones on the ceiling for lighting.

The IRC (International Residentail Code) up to 2006 (LINK) allowed the following exceptions for GFCIs in garages:

• Receptacles that are not readily accessible.
• A single receptacle or a duplex receptacle for two appliances located within dedicated space for each appliance that in normal use is not easily moved from one place to another, and that is cord- and plug-connected.

That disappeared in 2009 (LINK):

• All 125-volt, single-phase, 15- or 20-ampere receptacles installed in garages and grade-level portions of unfinished accessory buildings used for storage or work areas shall have ground-fault circuit-interrupter protection for personnel.

If your AHJ is still using the 2006 code - or earlier - you have the exceptions.

[Steve Meliza]

GFCI - I was told that 'any' outlet had to be on a GFCI. Even the ones on the ceiling for lighting. Another thing the inspector wanted was tamper proof outlets.

Not sure if you have to get it inspected, but you may want to ask beforehand. My inspector was actually very helpful, and grateful, when I asked the questions. It saved him a trip or two.

Agreed, and it can vary a lot between locations. For example, here in Oregon everything in the garage must be GFCI except if you have a single outlet (a duplex is two outlets) for a device such as a freezer and that device blocks access to the outlet, or words that that effect. Anything 5.5' above the floor or less gets a TR outlet.

Personally I hate having GFCI outlets sprinkled all over the place and having to hunt them down so I've resorted to $36 GFCI breakers for many of the circuits.

[Andy McKenzie]

Agreed, and it can vary a lot between locations. For example, here in Oregon everything in the garage must be GFCI except if you have a single outlet (a duplex is two outlets) for a device such as a freezer and that device blocks access to the outlet, or words that that effect. Anything 5.5' above the floor or less gets a TR outlet.

Personally I hate having GFCI outlets sprinkled all over the place and having to hunt them down so I've resorted to $36 GFCI breakers for many of the circuits.

Yep. Something pops, and you know it's on the panel. Either the circuit breaker tripped, or the GFCI did, and they're both right there. It really just feels like a better idea to me.