Shop wiring advice

[Cecil]

A couple of months ago, y'all gave me advice about putting 220 in the shop.  Basically I am planning on running 2, 220, non-dedicated circuits, with each circuit having multiple outlets on the wall and ceiling.

As I get ready to do the electrical work, I am looking for advice on the 120.  Currently there is a single 120V circuit feeding all the receptacles in the wood shop.  I plan on adding 2 more.  I know it will take more wire, but I am thinking about putting every third receptacle on a circuit, rather than grouping them, one circuit per area.  My wood shop is a 4 car garage. 

Think, 1 2 3 1 2 3 1 2 3 rather than 1 1 1 2 2 2 3 3 3.

Other than the extra expense for the wire, what are the pros and cons of this.  I know code will make me separate the wires (no more than 2 under a staple, through a hole, etc.).  Thanks.

[rwe2156]

A couple of months ago, y'all gave me advice about putting 220 in the shop.  Basically I am planning on running 2, 220, non-dedicated circuits, with each circuit having multiple outlets on the wall and ceiling.

As I get ready to do the electrical work, I am looking for advice on the 120.  Currently there is a single 120V circuit feeding all the receptacles in the wood shop.  I plan on adding 2 more.  I know it will take more wire, but I am thinking about putting every third receptacle on a circuit, rather than grouping them, one circuit per area.  My wood shop is a 4 car garage. 

Think, 1 2 3 1 2 3 1 2 3 rather than 1 1 1 2 2 2 3 3 3.

Other than the extra expense for the wire, what are the pros and cons of this.  I know code will make me separate the wires (no more than 2 under a staple, through a hole, etc.).  Thanks.

Yes, good idea. When I had my shop wired, the electricians did it that way, just ran 3 hots different colors, neutral, ground and labelled circuit breakers accordingly.  Of course if you use conduit it is much easier.

Something REALLY handy is you can split an outlet into separate circuits.  For example if you want plug a shop vac and miter saw into the same outlet.

[Islandman]

A couple of months ago, y'all gave me advice about putting 220 in the shop.  Basically I am planning on running 2, 220, non-dedicated circuits, with each circuit having multiple outlets on the wall and ceiling.

As I get ready to do the electrical work, I am looking for advice on the 120.  Currently there is a single 120V circuit feeding all the receptacles in the wood shop.  I plan on adding 2 more.  I know it will take more wire, but I am thinking about putting every third receptacle on a circuit, rather than grouping them, one circuit per area.  My wood shop is a 4 car garage. 

Think, 1 2 3 1 2 3 1 2 3 rather than 1 1 1 2 2 2 3 3 3.

Other than the extra expense for the wire, what are the pros and cons of this.  I know code will make me separate the wires (no more than 2 under a staple, through a hole, etc.).  Thanks.

you might make sure some of your lighting is split between at least two breakers, so that if you're working one night and pop a breaker, you will not lose all your lighting.

[panamint]

A couple of months ago, y'all gave me advice about putting 220 in the shop.  Basically I am planning on running 2, 220, non-dedicated circuits, with each circuit having multiple outlets on the wall and ceiling.

As I get ready to do the electrical work, I am looking for advice on the 120.  Currently there is a single 120V circuit feeding all the receptacles in the wood shop.  I plan on adding 2 more.  I know it will take more wire, but I am thinking about putting every third receptacle on a circuit, rather than grouping them, one circuit per area.  My wood shop is a 4 car garage. 

Think, 1 2 3 1 2 3 1 2 3 rather than 1 1 1 2 2 2 3 3 3.

Other than the extra expense for the wire, what are the pros and cons of this.  I know code will make me separate the wires (no more than 2 under a staple, through a hole, etc.).  Thanks.

Here is some info I saved from another person asking for advice with wiring a shop. I did not write this or have not check any of this info to see if it up to code. Just use it for ideas for your shop.


Firstly, since you are not overly familiar with electrical I'm kind of hoping the following advice will be used for the sake of communicating your needs and wishes to a licensed electrician.
 
For the conduit you may opt to use either gray PVC electrical conduit or steel EMT. EMT looks much nicer and, with a bit of skill, can be bent to conform to necessary turns and around obstructions in ways that PVC does not readily lend itself towards. The "skill" part of the equation is key, though. Most of your conduit runs will consist of a mix of 1/2" and 3/4" conduit, though the feed to your subpanel will be considerably larger (likely 1-1/4" to 1-1/2") and require a comparably sized hole in your walls to reach the main panel. If you opt for EMT, you will likely discover you end up using considerably more 1/2" than you do 3/4". Whatever you opt to use, consult Code fill tables (or search for an earlier post of mine that includes the fill charts) and avoid over filling your conduit.
 
For your sub panel you will want to run a 100A panel of around 20-24 circuits which will require a single double-pole breaker in your main panel. If running copper I suggest opting for #2AWG, or #1AWG if using aluminum for the feeder. I would go ahead and run a #4 copper ground, though Code will allow you to get by with much less (as little as #8 copper or #6 aluminum) -- I like to keep resistance to ground to a bare minimum (then again, I tend to have lots of electronics and PCs lying around).
 
For your drill press, and other motors of 1HP or less, there is really no advantage to converting these to 220V, so go ahead and keep them wired for 120V and run them off your regular 120V accessory receptacles along with your existing 120V power hand-held and mobile tools.
 
Plan for 2 20A 120V receptacle circuits along each of your major walls. Install 4 receptacle blocks (a pair of duplex receptacles) with each duplex receptacle on its own circuit. This will allow you to plug a high-demand tool like a portable thickness planer, shop vac, etc. in one side while still allowing you a second circuit (in the neighbouring receptacle) for a second device without overloading either circuit. ALL of your 120V receptacles (with rare exceptions I won't touch on here) should be GFCI protected with either GFCI circuit breakers OR an upstream GFCI receptacle. I tend to prefer the breakers even though they cost more because you can always reset them at the panel -- GFCI receptacles sometimes get buried behind other junk. If you opt for the cheaper GFCI receptacles purchase the 20A rated receptacles with an indicator lamp. For all your 120V receptacles opt for 'spec grade' (typically individually packaged) 5-20R receptacles -- these will hold up to the abuse in a shop environment and can safely deliver the full 20A circuit rating to a single device when needed. I like to wire heavy-duty 120V shop circuits with #10AWG copper to reduce voltage drop under high loads, but you can wire with #12AWG if on a tight budget.
 
For heating, I would suggest one or two 4-5KW electric heaters, many of which include ceiling mounts to help keep them up and out of the way and a safe distance from combustibles. A 4KW resistive heater will require a 20-25A circuit breaker, a 5KW will need a 25-30A breaker. Your ordinary household space heaters are typically limited to no more than 1500W and tend to be woefully inadequate when it comes to heating even a modest sized shop (unless you have exceptional insulation).
 
Don't forget to account for a 20-30A dedicated 240V circuit for a future Cyclone DC (same circuit can still be used for a lesser DC wired for 220V and a 15-20A breaker). Run #10AWG copper to this circuit (#12 ground), which will allow it to be upsized to 30A should you ever need to. The DC will run at the same time as your other power tools, so it needs a dedicated circuit all its own and can not be shared with any other tool.
 
Most of your 240V power tools can be serviced by 20A receptacles, but go ahead and wire these with #10AWG copper so that you can convert selected receptacles/circuits to 30A where necessary to handle larger motors. Some 3HP motors are rated for 20A circuits while some may require 25-30A (refer to owners manual). Your 5HP air compressor will require a dedicated 30A (and possibly 40A -- in which case you will need to run #8 copper w/ #12 ground) circuit all its own -- you may either hardwire it directly with a local disconnect switch OR you can wire it to a plug with an L6-30R/P (if 30A) receptacle/plug in which case the disconnect switch is not required.
 
Unless you know exactly what your layout will be for the next 4 years, I suggest you install at least 2 non-dedicated (e.g. not counting DC, compressor, heaters, etc.) 240V circuits and receptacles along each major wall in your shop (this is based upon my experiences). This will allow most of your larger 240V tools to connect to the nearest receptacle without long extension cords without having to constantly plug and unplug tools. Feel free to modify this suggestion depending upon your anticipated layout. For your 20A receptacles you may either use ordinary 3-prong 6-20R receptacles or the twist-lock L6-20R receptacles. Wire these circuits with #10AWG copper (and #12 ground) so that they can be adapted to 30A circuits if needs dictate such for a specific tool. GFCI protection (in the form of GFCI breakers) is not required for 220V circuits, but I would still advise investing in 220V GFCI breakers if there are specific circuits that may be used in wet or damp environments (e.g. out in the driveway) such as with your welders -- this will give you protection if you get caught in the rain while welding, etc.
 
Your arc welder, at 50A, will, of course, require a circuit all its own using a 50A receptacle and should be wired with #6AWG copper (and #12AWG ground) unless its manual states that a smaller guage may be used -- in which case I still suggest going one gauge size larger than the manual calls for if it is smaller than #6. The #6 wire will require at least 1" EMT conduit.
 
For your lighting circuit I like the 2-tube 4' flourescent F32T8 lamps with modern electronic ballasts. If you have white ceilings you can save money by purchasing the non-reflector models. If you lack white ceilings then you will need the reflector. For a typical 2-car garage you will likely want about 10-12 such fixtures. I also suggest purchasing 2 to 4 emergency lights (available from Lowes and HD) to complement your lighting. These lights should be placed on their own dedicated circuit, shared only with the emergency lights and POSSIBLY your ceiling mounted ambient air filter, but nothing more. Since these circuits (and possible receptacles) will NOT be accessible from floor level, you will not require a GFCI for this 120V circuit. You may wish to wire your lighting as two distinct banks that can be individualy switched. I have my lighting in two banks, each representing 50% illumination so that I can have 1) no lights, 2) 50% lighting and 3) 100% lighting. The emergency lamps should be located about 5-6ft in from each wall and their light heads aimed towards your major stationary tools and workbench. My shop required 3 such units for reasonable illumination. The emergency lights will allow you to quickly locate the OFF switch on your power tools while ensuring your hands remain a safe distance from the blade while you switch them off -- without emergency lights you are left fumbling in the dark at night and could have a terrible accident if the power suddenly comes back on after a second or two! They are very cheap insurance.
 
If you do any sort of proper Code installation with your new shop electrical, you are probably going to find that while there is good money tied up in it all, it will probably not be worth the hassle of tearing it all out and patching the walls (even with conduit and surface mounted outlets there are still lots of screw holes) when it comes time to move. The conduit and wiring left over after you tear it out will be in lots of odd lengths that make future use more challenging with lots of waste and the outlets, switches, and receptacles are not where the money is. The real money is in the load center (panel) and the breakers with a bit more invested in $40-60/ea lighting fixtures. Tearing out a load center, even a sub panel, is a lot of work when you realize that it all still has to look good before you can sell your house -- otherwise the mess you make will cost you more in terms of sale price than you saved by tearing it all out for re-use at your next place.
 
When it comes time to punch holes in your brick, you will want a good rotary hammer drill for the job. They will punch through brick like a hot knife through butter.
 
If you have not already done so, this is a great time to install a double-pole Surge Breaker in your main panel. If you have not had your ground rod tested for resistance and your home is an older home with a single ground rod, I would strongly encourage you to have 2 additional 10ft ground rods each driven 6ft to either side of the existing ground rod. Low ground resistance is key to the proper dissipation of power surges and lightning strikes. All the surge protection in the world will fail to do its job when it really counts without a good low-resistance path to ground that the traditional single ground rod seldom provides.
 
I am hoping this answers most of your questions, but I also know it has likely created a few new ones as well. Feel free to ask and I am sure there are others here who can recommend a good licensed electrician in your area.
 
My comments should all be consistent with the 2008 NEC Code (I don't have the 2011 book) but your local Codes may vary, when in doubt ask your local inspector(s) for relevant advice as their word is always the final authority. For the usual legal disclaimer: I am not a licensed electrician. My grandfather was the electrician in the family and I spent a good many of my earlier years (and most of my childhood) assisting him with primarily residential and small-business electrical.

[Cecil]

panamint:

I can glean some good info from that, but I have a hobby shop, in a residential neighborhood.  That looks like industrial wiring to me. 

RE: Receptacles, I believe buying a better quality is the right thing to do.  However, how do I know a receptacle is "spec grade?"  I don't believe just because it is individually wrapped it is better.

[Alan S]

... I am looking for advice on the 120.  Currently there is a single 120V circuit feeding all the receptacles in the wood shop.  I plan on adding 2 more.  I know it will take more wire, but I am thinking about putting every third receptacle on a circuit, rather than grouping them, one circuit per area. ...

I ran two 20A 120V circuits with groups of outlets every 6-10 feet.  The way I placed them was to use boxes with two double outlets in each, one pair of outlets on each circuit.  I used different colored outlets for each circuit (just white and ivory).  That way I can use either circuit in any spot, and tell at a glance which circuit something is on.

[Foggy]

Here is some info I saved from another person asking for advice with wiring a shop. I did not write this or have not check any of this info to see if it up to code. Just use it for ideas for your shop.


Firstly, since you are not overly familiar with electrical I'm kind of hoping the following advice will be used for the sake of communicating your needs and wishes to a licensed electrician.
 
For the conduit you may opt to use either gray PVC electrical conduit or steel EMT. EMT looks much nicer and, with a bit of skill, can be bent to conform to necessary turns and around obstructions in ways that PVC does not readily lend itself towards. The "skill" part of the equation is key, though. Most of your conduit runs will consist of a mix of 1/2" and 3/4" conduit, though the feed to your subpanel will be considerably larger (likely 1-1/4" to 1-1/2") and require a comparably sized hole in your walls to reach the main panel. If you opt for EMT, you will likely discover you end up using considerably more 1/2" than you do 3/4". Whatever you opt to use, consult Code fill tables (or search for an earlier post of mine that includes the fill charts) and avoid over filling your conduit.
 
For your sub panel you will want to run a 100A panel of around 20-24 circuits which will require a single double-pole breaker in your main panel. If running copper I suggest opting for #2AWG, or #1AWG if using aluminum for the feeder. I would go ahead and run a #4 copper ground, though Code will allow you to get by with much less (as little as #8 copper or #6 aluminum) -- I like to keep resistance to ground to a bare minimum (then again, I tend to have lots of electronics and PCs lying around).
 
For your drill press, and other motors of 1HP or less, there is really no advantage to converting these to 220V, so go ahead and keep them wired for 120V and run them off your regular 120V accessory receptacles along with your existing 120V power hand-held and mobile tools.
 
Plan for 2 20A 120V receptacle circuits along each of your major walls. Install 4 receptacle blocks (a pair of duplex receptacles) with each duplex receptacle on its own circuit. This will allow you to plug a high-demand tool like a portable thickness planer, shop vac, etc. in one side while still allowing you a second circuit (in the neighbouring receptacle) for a second device without overloading either circuit. ALL of your 120V receptacles (with rare exceptions I won't touch on here) should be GFCI protected with either GFCI circuit breakers OR an upstream GFCI receptacle. I tend to prefer the breakers even though they cost more because you can always reset them at the panel -- GFCI receptacles sometimes get buried behind other junk. If you opt for the cheaper GFCI receptacles purchase the 20A rated receptacles with an indicator lamp. For all your 120V receptacles opt for 'spec grade' (typically individually packaged) 5-20R receptacles -- these will hold up to the abuse in a shop environment and can safely deliver the full 20A circuit rating to a single device when needed. I like to wire heavy-duty 120V shop circuits with #10AWG copper to reduce voltage drop under high loads, but you can wire with #12AWG if on a tight budget.
 
For heating, I would suggest one or two 4-5KW electric heaters, many of which include ceiling mounts to help keep them up and out of the way and a safe distance from combustibles. A 4KW resistive heater will require a 20-25A circuit breaker, a 5KW will need a 25-30A breaker. Your ordinary household space heaters are typically limited to no more than 1500W and tend to be woefully inadequate when it comes to heating even a modest sized shop (unless you have exceptional insulation).
 
Don't forget to account for a 20-30A dedicated 240V circuit for a future Cyclone DC (same circuit can still be used for a lesser DC wired for 220V and a 15-20A breaker). Run #10AWG copper to this circuit (#12 ground), which will allow it to be upsized to 30A should you ever need to. The DC will run at the same time as your other power tools, so it needs a dedicated circuit all its own and can not be shared with any other tool.
 
Most of your 240V power tools can be serviced by 20A receptacles, but go ahead and wire these with #10AWG copper so that you can convert selected receptacles/circuits to 30A where necessary to handle larger motors. Some 3HP motors are rated for 20A circuits while some may require 25-30A (refer to owners manual). Your 5HP air compressor will require a dedicated 30A (and possibly 40A -- in which case you will need to run #8 copper w/ #12 ground) circuit all its own -- you may either hardwire it directly with a local disconnect switch OR you can wire it to a plug with an L6-30R/P (if 30A) receptacle/plug in which case the disconnect switch is not required.
 
Unless you know exactly what your layout will be for the next 4 years, I suggest you install at least 2 non-dedicated (e.g. not counting DC, compressor, heaters, etc.) 240V circuits and receptacles along each major wall in your shop (this is based upon my experiences). This will allow most of your larger 240V tools to connect to the nearest receptacle without long extension cords without having to constantly plug and unplug tools. Feel free to modify this suggestion depending upon your anticipated layout. For your 20A receptacles you may either use ordinary 3-prong 6-20R receptacles or the twist-lock L6-20R receptacles. Wire these circuits with #10AWG copper (and #12 ground) so that they can be adapted to 30A circuits if needs dictate such for a specific tool. GFCI protection (in the form of GFCI breakers) is not required for 220V circuits, but I would still advise investing in 220V GFCI breakers if there are specific circuits that may be used in wet or damp environments (e.g. out in the driveway) such as with your welders -- this will give you protection if you get caught in the rain while welding, etc.
 
Your arc welder, at 50A, will, of course, require a circuit all its own using a 50A receptacle and should be wired with #6AWG copper (and #12AWG ground) unless its manual states that a smaller guage may be used -- in which case I still suggest going one gauge size larger than the manual calls for if it is smaller than #6. The #6 wire will require at least 1" EMT conduit.
 
For your lighting circuit I like the 2-tube 4' flourescent F32T8 lamps with modern electronic ballasts. If you have white ceilings you can save money by purchasing the non-reflector models. If you lack white ceilings then you will need the reflector. For a typical 2-car garage you will likely want about 10-12 such fixtures. I also suggest purchasing 2 to 4 emergency lights (available from Lowes and HD) to complement your lighting. These lights should be placed on their own dedicated circuit, shared only with the emergency lights and POSSIBLY your ceiling mounted ambient air filter, but nothing more. Since these circuits (and possible receptacles) will NOT be accessible from floor level, you will not require a GFCI for this 120V circuit. You may wish to wire your lighting as two distinct banks that can be individualy switched. I have my lighting in two banks, each representing 50% illumination so that I can have 1) no lights, 2) 50% lighting and 3) 100% lighting. The emergency lamps should be located about 5-6ft in from each wall and their light heads aimed towards your major stationary tools and workbench. My shop required 3 such units for reasonable illumination. The emergency lights will allow you to quickly locate the OFF switch on your power tools while ensuring your hands remain a safe distance from the blade while you switch them off -- without emergency lights you are left fumbling in the dark at night and could have a terrible accident if the power suddenly comes back on after a second or two! They are very cheap insurance.
 
If you do any sort of proper Code installation with your new shop electrical, you are probably going to find that while there is good money tied up in it all, it will probably not be worth the hassle of tearing it all out and patching the walls (even with conduit and surface mounted outlets there are still lots of screw holes) when it comes time to move. The conduit and wiring left over after you tear it out will be in lots of odd lengths that make future use more challenging with lots of waste and the outlets, switches, and receptacles are not where the money is. The real money is in the load center (panel) and the breakers with a bit more invested in $40-60/ea lighting fixtures. Tearing out a load center, even a sub panel, is a lot of work when you realize that it all still has to look good before you can sell your house -- otherwise the mess you make will cost you more in terms of sale price than you saved by tearing it all out for re-use at your next place.
 
When it comes time to punch holes in your brick, you will want a good rotary hammer drill for the job. They will punch through brick like a hot knife through butter.
 
If you have not already done so, this is a great time to install a double-pole Surge Breaker in your main panel. If you have not had your ground rod tested for resistance and your home is an older home with a single ground rod, I would strongly encourage you to have 2 additional 10ft ground rods each driven 6ft to either side of the existing ground rod. Low ground resistance is key to the proper dissipation of power surges and lightning strikes. All the surge protection in the world will fail to do its job when it really counts without a good low-resistance path to ground that the traditional single ground rod seldom provides.
 
I am hoping this answers most of your questions, but I also know it has likely created a few new ones as well. Feel free to ask and I am sure there are others here who can recommend a good licensed electrician in your area.
 
My comments should all be consistent with the 2008 NEC Code (I don't have the 2011 book) but your local Codes may vary, when in doubt ask your local inspector(s) for relevant advice as their word is always the final authority. For the usual legal disclaimer: I am not a licensed electrician. My grandfather was the electrician in the family and I spent a good many of my earlier years (and most of my childhood) assisting him with primarily residential and small-business electrical.

Heat PVC until it's soft and it can be formed much better and easier than bending EMT. Just get it hot, hold it in place for whatever goofy bend you need, cool with a wet rag.

[DFJarvie]

I'm the last guy to say get an electrician but it sounds like you need some power to the shop. Good advice about panels above but get someone to figure out what you need for a panel.

You need minimum 50 amps or more in the shop. A TS and D.C. Eat up 20 amps then you may need AC or heat. More amps added.

You can get the electrician to set up the panel and you can run all the wiring. If you feel comfortable you can make all the connections in the box.

You want to make sure you have enough power so you can do what you want.

[®smpr_fi_mac®]

I'm in the process of wiring my shop, too. Like you, I'm adding *lots* of outlets. My shop is 24x24x12'. I installed a 60A box in the garage to provide power.

I'm only running two 120V, 20A circuits for outlets, though. I'm spacing the outlets every 4-6'. I'm using 2-gang work boxes, with two sets of outlets in each one. All of the *left* side outlets in the boxes are one circuit; all the *right* side ones are the other circuit.

I have another circuit for my lighting (LED strip lights on the ceiling).

I'll install another two 120V, 20A circuits to handle two air scrubbers on one and two ceiling fans on the other.

I'm running two 220V, 30A lines, but only because it's convenient to run two instead of just one. On those two circuits will be a total of six 220V outlets for my stationary equipment.

Hope this helps a bit.

[HomerLee]

I built a 24' x 30' shop years ago. Stick built and insulated. Ran a gas line and installed a gas wall furnace so I do not need to worry about circuits and watts used for heat. My sub-panel in the shop is 60 amps which has been adequate for all I've ever needed. There is such a thing as demand factor to consider. If the shop is intended for one man, how many machines can you run at one time? My worst case is running my 3hp cabinet saw, dust collector, and having my air compressor automatically start. With a 60 amp panel I have never had a problem.

IMO a hundred amp panel for most woodworking is overkill unless there will be multiple people working.

(Former licensed electrical supervisor)