220 circuits

[Rodbolt]

I am beginning the process of wiring my new garage and would like some input on 220 volt outlets. I'm wiring a 30 amp circuit for my compressor. I want to also run a few others for welding/plasma cutting. Here's my dilemma. What amperage of 220 circuit should I put in, and how many 220 outlets do you have in your shop? I don't currently have a 220 welder or plasma cutter but would like to upgrade in the future. Are 50 amp outlets sufficient? Going higher significantly increases in copper $$$. Also, is it worth the expense and trouble to have 3 or 4 220V outlets in the shop so you don't have to run an extension cord to your welder? Thanks for all your help out there!


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[Milton Shaw]

I would recommend putting some lower amp outlets in also. Compressor would normally be a 20 amp etc. If you add any 220 volt equipment then additional circuits would be a problem saver. 50 amp for most light industrial equipment - welders and plasma cutters would be the standard.

 

[Charles (in GA)]

Without knowing what equipment you will be running, and where in the shop it will be placed, its about impossible to determine what you need to install. You could end up wasting a bunch on wire and receptacles to discover that it isn't enough or in the right places.

Plasma and Compressed air (and possibly a refrigerated air dryer for the compressor due to the plasma's need for very clean dry air) will run at the same time. What of amps of service do you have to the shop. Detached?, attached? (to the house) separate service? supplied from the house?

Its240 volt, NOT 220 volt.

Charles

 

[Rodbolt]

Without knowing what equipment you will be running, and where in the shop it will be placed, its about impossible to determine what you need to install. You could end up wasting a bunch on wire and receptacles to discover that it isn't enough or in the right places.

Plasma and Compressed air (and possibly a refrigerated air dryer for the compressor due to the plasma's need for very clean dry air) will run at the same time. What of amps of service do you have to the shop. Detached?, attached? (to the house) separate service? supplied from the house?

Its240 volt, NOT 220 volt.

Charles

I'm not sure what equipment the future might hold otherwise I'd spec it out accordingly. I'm interested in feedback from guys who've had 50 amp outlets and been able to run larger mig welders for instance. I'm thinking of outlets near the main working areas and one by the door in case I want to weld in the driveway. It's a stick frame shop so I'm a bit under the gun to do wiring now before the drywall goes in so I'm trying to make good decisions there.

The shop is detached from the house and has its own dedicated 200 amp service from the power pole so power is not a problem.


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[PowerMan]

I'm not sure what equipment the future might hold otherwise I'd spec it out accordingly. I'm interested in feedback from guys who've had 50 amp outlets and been able to run larger mig welders for instance. I'm thinking of outlets near the main working areas and one by the door in case I want to weld in the driveway. It's a stick frame shop so I'm a bit under the gun to do wiring now before the drywall goes in so I'm trying to make good decisions there.

The shop is detached from the house and has its own dedicated 200 amp service from the power pole so power is not a problem.


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The problem is protection against fires. If you run a 50A circuit, and you plug in, lets say your 3HP compressor, legally the 50A breaker is too big to protect that compressor motor from catching on fire if there is a problem inside of it. The National Electric Code specifically dictates the size of circuit you need in terms of minimum (for wire size) but also maximum (for device protection). So unless you know the size of the motor or load (welder / plasma cutter), you can't really go around just running wires everywhere yet. It will take some advanced planning.

And don't think that (aside from being expensive) you can just get away with running 50A wire everywhere, then connecting it to a 20A breaker if the device needs closer protection. It's unlikely that you can fit the wire size necessary for 50A into the terminals of a 20A breaker.

If it were me, I would run mostly 10ga wire, which is good for 30A (in most garage distances) because that will fit in a 20A or 30A breaker and receptacle terminals and the difference in cost for short runs of 10ga vs 12ga is minimal. Then if you use a 20A receptacle and a 20A breaker, the wire is over sized but that's OK. If you need 30A, you are ready and all you need do is change the receptacle and breaker. For the 40 and 50A circuits, I would look at exactly what needs those and where you want to put them.

 

[2ManyProjects]

I am beginning the process of wiring my new garage and would like some input on 220 volt outlets. I'm wiring a 30 amp circuit for my compressor. I want to also run a few others for welding/plasma cutting. Here's my dilemma. What amperage of 220 circuit should I put in, and how many 220 outlets do you have in your shop? I don't currently have a 220 welder or plasma cutter but would like to upgrade in the future.

As Charles points out, the only way to be sure is to know what equipment you're (eventually) going to have in there. Failing that, its all guesswork, pure and simple. If for whatever reason you MUST do that guesswork now, the only semi-safe assumption is that you will eventually want/need more capacity than you (now) think; so "guess high".

Are 50 amp outlets sufficient?

Sufficient FOR WHAT? Without knowing that, it is impossible to answer reliably or usefully.

Going higher significantly increases in copper $$$.

True. But it's still way cheaper than putting in something which later turns out to be insufficient, and thus having to not only (eventually) spend the $$$ for the high-capacity stuff, but also write off your investment in the "bargain basement" stuff. Not to mention the additional (duplicated) work.

Also, is it worth the expense and trouble to have 3 or 4 220V outlets in the shop so you don't have to run an extension cord to your welder?

This is strictly a question of convenience vs. cost, and thus a judgement call. Hence, only you can answer that.

I would recommend putting some lower amp outlets in also. Compressor would normally be a 20 amp etc.

That's not a safe assumption. There are MANY "moderate" size compressors out there which would require at least a 30A circuit; I daresay, very possibly more of them than those which would be happy on a 20A feed. Just for example, ALL of these: http://www.aircompressorsdirect.com/tools/3-hp-single-stage-air-compressors.html would require more than 20A.

If you add any 220 volt equipment then additional circuits would be a problem saver. 50 amp for most light industrial equipment - welders and plasma cutters would be the standard.

Again, you're painting with too wide a brush. Welders have their own oddball requirements; and IF the outlet is dedicated to an arc welder, the wiring serving that outlet can actually be much lighter than you would normally think (whether or not this is a good idea remains a separate discussion). Plasma cutters are all over the map, in terms of their power requirements; some can even require 480V 3-phase (tho' the odds on such an "ambitious" model being found in a home hobbyist's shop are probably pretty slim). The point is, WE JUST DON'T KNOW.

I'm not sure what equipment the future might hold otherwise I'd spec it out accordingly. I'm interested in feedback from guys who've had 50 amp outlets and been able to run larger mig welders for instance. I'm thinking of outlets near the main working areas and one by the door in case I want to weld in the driveway. It's a stick frame shop so I'm a bit under the gun to do wiring now before the drywall goes in so I'm trying to make good decisions there.

Here's a thought... Instead of trying to predict things you really can't yet know, run some generously sized conduit from the service panel to ALL the locations where you THINK you might want a 240V power outlet, leaving a pull rope (but nothing else) inside each run. At each of those outlet those locations, install a box with a blank plate, and call it "Done" for now. If/when you do decide on exactly what equipment you're going to put at one of those locations, you can use the pull rope to run properly sized THHN through the conduit, and install your outlet (or a local disconnect for hardwired equipment -- which would include at least most of those air compressors I cited above, BTW). Obviously, the pull rope should be a bit more than double the length of the conduit run, so that it can be used repeatedly for multiple pulls.

The shop is detached from the house and has its own dedicated 200 amp service from the power pole so power is not a problem.

Good.

The problem is protection against fires. If you run a 50A circuit, and you plug in, lets say your 3HP compressor, legally the 50A breaker is too big to protect that compressor motor from catching on fire if there is a problem inside of it.

That is DEAD WRONG.

There is absolutely NO requirement for the breaker in the service (or sub-) panel to protect whatever equipment might be plugged into an outlet. Nor is that breaker even remotely intended to do so. Its SOLE job is to protect the WIRE running from that panel to the outlet, period.

The equipment itself (whatever it might be) should (and at least usually will) have its own over-current protection, if needed.

The National Electric Code specifically dictates the size of circuit you need in terms of minimum (for wire size) but also maximum (for device protection).

Really? Let's pretend I'm from Missouri: Show Me.

I know of NO provision of the NEC which prohibits oversizing wires.

And don't think that (aside from being expensive) you can just get away with running 50A wire everywhere, then connecting it to a 20A breaker if the device needs closer protection. It's unlikely that you can fit the wire size necessary for 50A into the terminals of a 20A breaker.

Red Herring.

If the wire is adequate for 50A, then there would be absolutely NO reason to use a 20A breaker, ever; so this is a moot point.

 

[coolreed]

The Amperage requirement depends on the Welder you want to use.

I would recommend at least a dedicated 50A circuit for welding.

I would also recommend at least a 30A capacity for a compressor.

In addition, if you want to run four 220 outlets I would have each on it's own circuit breaker.

Do not worry about the cost of wire. Just use the proper sized copper wire for each circuit. Make sure all connections are tight.

I have two 220 outlets in my garage. One is a 50A Circuit and one is a 30A.

Be Safe and Best of Luck

 

[Milton Shaw]

One thing that has not been suggested is to run 10/3w/g and then tape off the red wire at each end. That way you are ready for 240 30amp at any location with just an outlet and breaker change. There again not much more expense than running just 12 /2/w/g, or at least not as expensive as doing it over with the heaver wire at a later time.

 

[pattenp]

Do you mind explaining your thinking a little further. I'm not following. If it's a single purpose 240V circuit with one outlet then why use three conductors?

One thing that has not been suggested is to run 10/3w/g and then tape off the red wire at each end. That way you are ready for 240 30amp at any location with just an outlet and breaker change. There again not much more expense than running just 12 /2/w/g, or at least not as expensive as doing it over with the heaver wire at a later time.

 

[Rodbolt]

One thing that has not been suggested is to run 10/3w/g and then tape off the red wire at each end. That way you are ready for 240 30amp at any location with just an outlet and breaker change. There again not much more expense than running just 12 /2/w/g, or at least not as expensive as doing it over with the heaver wire at a later time.

I don't foresee the need for three conductors. I think most of the replies have missed the real root of my question and instead argued details. Basically, do you wish you had wired more 240 outlets in your shop, and has 50 amps limited you in any way or is it enough service for most hobby welding/shop projects. I know that my compressor and lift are much smaller circuits, I've already designated them.


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[Kevin C]

I have a couple of empty runs of 3/4" conduit to the back of the shop. Each one terminates to a 4" box. REasy to pull wire later. I hid the runs behind sheet rock.

 

[wyliesdiesels]

As Charles points out, the only way to be sure is to know what equipment you're (eventually) going to have in there. Failing that, its all guesswork, pure and simple. If for whatever reason you MUST do that guesswork now, the only semi-safe assumption is that you will eventually want/need more capacity than you (now) think; so "guess high".

Sufficient FOR WHAT? Without knowing that, it is impossible to answer reliably or usefully.

True. But it's still way cheaper than putting in something which later turns out to be insufficient, and thus having to not only (eventually) spend the $$$ for the high-capacity stuff, but also write off your investment in the "bargain basement" stuff. Not to mention the additional (duplicated) work.

This is strictly a question of convenience vs. cost, and thus a judgement call. Hence, only you can answer that.

That's not a safe assumption. There are MANY "moderate" size compressors out there which would require at least a 30A circuit; I daresay, very possibly more of them than those which would be happy on a 20A feed. Just for example, ALL of these: http://www.aircompressorsdirect.com/tools/3-hp-single-stage-air-compressors.html would require more than 20A.

Again, you're painting with too wide a brush. Welders have their own oddball requirements; and IF the outlet is dedicated to an arc welder, the wiring serving that outlet can actually be much lighter than you would normally think (whether or not this is a good idea remains a separate discussion). Plasma cutters are all over the map, in terms of their power requirements; some can even require 480V 3-phase (tho' the odds on such an "ambitious" model being found in a home hobbyist's shop are probably pretty slim). The point is, WE JUST DON'T KNOW.

Here's a thought... Instead of trying to predict things you really can't yet know, run some generously sized conduit from the service panel to ALL the locations where you THINK you might want a 240V power outlet, leaving a pull rope (but nothing else) inside each run. At each of those outlet those locations, install a box with a blank plate, and call it "Done" for now. If/when you do decide on exactly what equipment you're going to put at one of those locations, you can use the pull rope to run properly sized THHN through the conduit, and install your outlet (or a local disconnect for hardwired equipment -- which would include at least most of those air compressors I cited above, BTW). Obviously, the pull rope should be a bit more than double the length of the conduit run, so that it can be used repeatedly for multiple pulls.

Good.

That is DEAD WRONG.

There is absolutely NO requirement for the breaker in the service (or sub-) panel to protect whatever equipment might be plugged into an outlet. Nor is that breaker even remotely intended to do so. Its SOLE job is to protect the WIRE running from that panel to the outlet, period.

The equipment itself (whatever it might be) should (and at least usually will) have its own over-current protection, if needed.

Really? Let's pretend I'm from Missouri: Show Me.

I know of NO provision of the NEC which prohibits oversizing wires.

Red Herring.

If the wire is adequate for 50A, then there would be absolutely NO reason to use a 20A breaker, ever; so this is a moot point.

Glad u corrected all the misinformation on this thread, especially that spat about fire hazards!