Electrical question

[Jason Morgan]

Im wiring the new Garage/shop and was wondering about wire gauge for my 220V circuits. Am I ok with 220V 1P circuits using 14/3 conductor? or do I need 12 or 10? These are going to be 20A circuits that will I think never see more than about 12 A draw (Im going to keep one tool per circuit)

Thanks

[Jason Morgan]

I did a search and found that I should be using at least 12 gauge and 10 would not hurt, but is not technically needed for 20 A circuits. I dont ever plan on running anything over 3hp motors and if I do, Ill run another dedicated circuit.

[Brian Weick]

Jason, that scenario , although current - may change- you should build in additions to your calculations so you don't have to re-wire your setup all over again. you should calculate the amperage of the machines your hooking up to that as well to determine the Gage of the wire and the circuit breaker at the panel-call your local electrical supply- give them the information of the machines and the E panel box and what you will be running- they will be able to tell you exactly what you need and more than happy to help. - Always go to a electrical supply store in your area to get answers on electrical systems and hookups- you don't want your building turning into ashes!
Brian

[Bill Arnold]

Jason,

When wiring my shop, I used 12/2 w/ground for all 110V circuits and 10/2 w/ground for all 220V circuits. At present, the largest motor on any 220V circuit is 3HP, but I wanted to be sure I had plenty of capacity for any future changes. Each 220V machine is on a dedicated circuit. Ceiling lights in each area of the shop are on seperate breakers; no more than five duplex 110V outlets are on a breaker. This arrangement provides for plenty of isolation.

[Jason Hanna]

Isn't the rule of thumb you figure the voltage/amps of the machine, and that tells you the size of breaker you need for the circuit (round up) and then size of the breaker tells you the size of the wire?

Never size the wire to the machine, always the wire to the breaker. If I'm not mistaken, it doesn't do you any good to grossly oversize the wire beyond the breaker unless you forsee swapping out the breaker in the future for a high amp breaker.

[Von Bickley]

Jason,

All my wiring in my shop is #12 and I did electrical work for many years.

[Josiah Bartlett]

You may want to wire at least some of the circuits with 3 conductors + ground in case you get a future machine that requires a neutral. Some welders do, and maybe other things will too.

[Eric Gustafson]

Jason,

All my wiring in my shop is #12 and I did electrical work for many years.

Von,

What is the highest load in your shop? Any 220v tools? Anything larger than 3 hp?

Just curious as I am determining my shop requirements now, including how large of a subpanel to install.

[Jason Morgan]

Thanks for all the help. I think I am going to go with the "overkill" approach and go 10/2 for the 220's and 12/2 for the 110's. Now to plan the layout and possible future additions. I know that I'll never have it perfect, I am just shooting for the max versitility.

Thanks again.

[Ken Fitzgerald]

Jason,

I built my shop 3 years ago. I wired the 120 circuits with 12/2 and the 220 circuits with 10/2......I just bought a bandsaw.....4.8 hp.....Sure glad I used 10/2 on those 220 circuits. The cost difference between the 12/2 and the 10/2 is miniscule as compared to how much time and effort it would take now to remove the plywood from the walls to rewire or even to run conduit externally to the interior walls. If your walls are open, I'd run 10/2 on the 220 circuits. JMHO....

[Roland Chung]

Jason,

If you want maximum versatility, consider installing a 3/4" emt (or bigger) conduit run from your subpanel and pull the appropriate wires as you need them.

How about a 100 amp panel -

Large compressor - 240v - 20A (or bigger) - 2 spaces
Dust collection - 240v - 20A (or larger) - 2 spaces
Lighting - 120v - 15A-20A - 1 space
Stationary tools - 240v - 20A x 2 - 2 spaces
Stationary tools - 120v - 20A x 2 - 2 spaces
Outlet circuits - 120v - 20A x 2 - 2 spaces

Not that you would be using anything close to the 100amps, but it might be hard to locate a smaller capacity subpanel with enough spaces. If you want to save a bit, only run the conduit and wire for your present needs, the conduit will allow you to pull additional wires as your needs change.

Want it behind the drywall, run flex.

[Von Bickley]

Von,

What is the highest load in your shop? Any 220v tools? Anything larger than 3 hp?

Just curious as I am determining my shop requirements now, including how large of a subpanel to install.

My highest load would probably be my contractor TS. I have it wired for 120 volts and will leave it like that in case I have to take it somewhere to use. I have a couple of 220 volt circuits but the only 220 volt tool that I'm presently using is a squirrel cage fan for air circulation.

My shop is inside a pole building that we are presently living in part of. We put in a kitchen area, a bath room with washer and dryer, and a bedroom. We will soon be starting construction on a new home and will pull power from the pole building to the new house.

The pole building has a 400 amp service with a 200 amp panel in the shop and temporary living area. We have a 200 amp disconnect outside to take power to the new house, and we have a manual transfer panel in the shop that we can hook up a 4500 watt generator to in case we lose power. The generator would only be used for a few lights, refrigerators and water pump.

[Rick Christopherson]

Thanks for all the help. I think I am going to go with the "overkill" approach and go 10/2 for the 220's and 12/2 for the 110's. Now to plan the layout and possible future additions. I know that I'll never have it perfect, I am just shooting for the max versitility.

Thanks again.

Jason, there is nothing wrong with using #10 wire for your 240 volt circuits, just so long as you understand that the likelihood of actually using it is going to be extremely low in a garage workshop. People advise others to do this all the time, telling them to plan ahead, however, this isn't planning ahead.

Just for comparison, a 3hp Delta Unisaw will run from a 15 amp circuit (but I wouldn't recommend it). For the typical garage workshop virtually all of the tools are 3 hp or less. The most notable exception is a 5hp compressor. Even though I have heard of some people putting in 5 hp dust collectors in their garage, this is kind of silly for the amount of space.

Number 10 wire is horrible to work with, and right now it is terribly expensive. Do you really foresee getting any 5 hp tools?

By the way, in your original posting you commented about 3 conductors (plus ground). This is not required, and used even less. I am not an expert on welders, that a previous poster commented on, but to the best of my knowledge, not even they require the neutral.

[SCOTT ANDREWS]

[



The pole building has a 400 amp service with a 200 amp panel in the shop and temporary living area. We have a 200 amp disconnect outside to take power to the new house, and we have a manual transfer panel in the shop that we can hook up a 4500 watt generator to in case we lose power. The generator would only be used for a few lights, refrigerators and water pump.[/quote]


I would kill to have 400 amp service.Nice

[Bob Feeser]

Im wiring the new Garage/shop and was wondering about wire gauge for my 220V circuits. Am I ok with 220V 1P circuits using 14/3 conductor? or do I need 12 or 10? These are going to be 20A circuits that will I think never see more than about 12 A draw (Im going to keep one tool per circuit)

Thanks

I just use the wire at what it is rated for. I am not an electrician, but to me 14/3 is for 15 amp lines, and I use a 15 amp outlet on it. For 20 amp I use 12/2 or 3 with a ground, always a ground, even if it is just to ground the outlet box. Then I put a 20 amp outlet on it, which has the right angle leg on it.

Without going into every line that enters my shop, if I had to do it over again, I would put a load center/panel in my shop. Run one large wire into the panel, thereby eliminating any concerns of wire distance, because thin wires have that concern over greater distances, and thick wires do not. Even more importantly, it is nice to be able to go to a single switch panel and turn the shop off at the end of the day. If electrical storms are present, like they are in my neck of the woods, you don't want all of your high power machines, plugged into outlets, waiting for a lightning arc. Since surge suppressors for 30 or 40 amp tools are hard, and expensive to come by, and the common ones that are rated for 15 amps are annoyingly always tripping when you turn on tools. Even my radial arm saw pops one of them, so 20 amp circuits are very popular for woodworking.

Consider running a couple of outlets off of one line, instead of limiting yourself to one wire for each outlet, especially with the price of copper. But consider which outlets they are, because you don't want your shop vac to be plugged into the same circuit as your tool. If you had an outlet you were sharing with your scroll saw, and the one you plugged your belt sander, or hand tool into, that would not be a concern, since you do not run these concurrently.

With a 200 amp, and a 125 amp panel feeding my house, I was able to run a lot of power into the shop. It is really nice being able to walk over to a dedicated station, and simply flip a switch. My shop is about 725 sq feet, which is sufficient to be able to do that. Positioning and layout helps a lot.

Don't plan your circuits based on what you anticipate the draw will be, but rather what the standard demand parameters dictate. My good buddy is a professional electrician, and I forget all of the specifics because it has been a while since the electric was upgraded. I will say that prior to the upgrade it was a real pain in the butt, having to plug and unplug stuff all of the time.

All of my 220 20 amp circuits are run with 12 gauge wire, except the one that is isolated for my heat pump band heater only. I don't want to jump off topic here about that one. I don't think you will run into too many 15 amp 220 circuits. It doesn't hurt to be running 12 gauge 20 amp for that. They key is to always match the circuit breaker with the gauge of the wire. The thing to be avoided is a 14 guage wire with a 20 amp breaker.

You know their are exceptions to every rule, and I am sure their is an electrical professional right now, blowing a breaker reading this, so take what I say with a little skepticism, like I said, I am not an electrician.

Instead of trying to make one circuit do all, think in terms of multiple outlets, each with their own rating and purpose. Hooking up a 15 amp tool to a 20 amp line is not going to give you the kind of protection for the tool overheating, let's say with a lockup, or jam, than if you had hooked it up to a 15. (Assuming the 15 amp breaker would break before the motor would cook completely)

On the other hand a 30 amp tool doesn't like to be starved with a smaller line either. Run as many different size outlets into the shop as you can, and use each of them at their ratings. Shop lights can run a lot of them off of a single 15 amp 14 guage wire.

Heavier equipment especially 220 volt 30 amp level is best run off of a dedicated line.
Hey at least I know enough to be dangerous. Hope this helps.