This weekend, my new shop walls are going up, and I need to start thinking about how to wire it. Ideally, this is what I want to do:
1 120V circuit for machines (many, many plugs)
1 220V circuit for hard core machines (a few plug)
1 120V circuit for lighting
1 120V circuit for any dust collection
The last circuit there would probably just be 1 whip across the floor joists to plug in a ceiling-mounted collector unit, so that's trivial and could even come off a circuit in the next room.
I plan on this shop being used for a hobbyist but I'm also thinking of resale of the home, especially if the potential buyer is any kind of handycraftsy person. Is 4 circuits too much? How many outlets would you recommend, and is that 220V line really necessary? I have no current plans for 220V machines but that doesn't mean I may not get them eventually. Is it really necessary to have the lights on their own circuit (this was recommended to me repeatedly, but nobody could tell me why).
That depends - are you with the code enforcement division? ;^)
I put it all in and ran it all in smurf tube so I could change it later if necessary. My shop has OSB walls so I can screw the conduit and outlets in where ever I need them.
Heh, no. I've done a few really tiny wiring projects (install a GFCB, for example), I'm just trying to guess if I can do all this on my own. I did took a few home electricity classes in high school, but that was 10 years ago.
I'd say if in doubt, don't take a chance burning the house down. Find an electrician that will let you do the grunt work and hook everything up for you.
Your plan seems sound enough. Watch the amperage on the circuit you have for machines; 20amps is my suggestion. I have a couple 20-amp circuits for machines which is not overkill given that I could easily have the compressor cut in (loss of pressure) if I started using a saw. Given the number of lights I have, I have two 15-amp circuits for lights. However, part of the reason for two circuits was to simplify the wiring.
As to the *potential* for 220V, it's trivial to convert that to/from
120 *if* you have sufficiently-sized wire (move the white to/from hot, change to/from ganged breakers).
As long as you have clear access the wiring part is rather easy. Check your local library for books on home wiring. There are likely some available which will get you acquainted with what you are going to do. If you aren't currently using 220V you can hook it up as 110 in the meantime. That way when you have a need for 220 all you need is a new breaker and a receptacle. Leave a bit of slack in the main panel so that you can rewire if that happens.
Good start. I'd check that "many, many" receptacles bit, though. IIRC, NEC limits 110 volt circuits to a max of 8 outlets per. If I even think 2 tools will be used on the circuit at one time, I add another circuit.
I'd guess your dust collector is a 110 volt. Many are 220. Make sure.
I'd also, if possible, run a second 220, or at least make sure there's space for the breaker. If you have no current 220 equipment, figure out how long you expect to stay in the house. If it's 5 years or more, and you keep woodworking, you'll want 220 gear at some point.
Lights are put on their own circuit for a simple reason: if you're feeding wood to your table saw and the saw binds, you will be glad the lights are on another circuit when the saw breaker blows.
Charlie Self
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Electrical circuits are like clamps, you can NEVER have too many.
The following are some general guidelines for a distribution system.
Use two (2) dedicated 20A ckts for lighting.
If you loose one, you still have the other.
Yes, you want 240V circuits, lots of them.
Your table saw will be much happier on 240VAC as opposed to 120VAC.
How about a decent air compressor and/or a dust collector, they both like
240 VAC.
Forget 15A circuits.
Use 20A c'bkrs and #12 AWG wire as a minimum for 120 VAC distribution.
Even though this shop is in your basement, consider adding a 60A panel fed from the main panel and dedicated to your shop.
Panels, c'bkrs and wire are relatively inexpensive. Labor is expensive; however, it is the job unknowns that really drive up the cost of the finished job.
Is lights on their own circuit _necessary_? No. *GOOD*IDEA*(tm)? hell yes.
why? what happens to the lights if "something else" sharing the circuit overloads and causes the breaker to blow?
The _first_ thing you need to do is consult the electrical code requirements for your locale. each 220 outlet may _have_ to be on a separate circuit, just for starters..
As for 4 circuits being "too many", I've got _ten_ circuits in my *kitchen*. (one for lights, one for stove, one for refrigerator, one for dishwasher, and _six_ circuits for the outlets.) Admittedly, I've got a -lot- of counter-top appliances, and running several at the same time _is_ likely e.g. electric skillet, microwave, toaster, bread machine, and blender.
I'd recommend at least 3 220 circuits. each with a single outlet. (Note, if you don't have 220 use _currently_, you can put a single 'split' duplex outlet in the box, and have 2 120VAC outlets -- until you need the 220u)
Then I'd add _at_least_ two 120V outlets, -- put *lots* of outlets around the walls, and alternate which circuits they're on. (you may need to run, for example, a vacuum and "something else")
*ANY* chance that 'more than one' person might be working in the place _at_the_same_time_ ?? If "absolutely not" (even in the future, after you've sold the place), then go ahead and wire to support *only*one* device in use at any time.
Other things to think about, that may affect electrical needs: Air conditioning? Dehumidifier?
Not enough IMO, if there is any possibility that more than one person will be working in the shop simultaneously. I recommend two 20A 120V circuits at a minimum for machinery.
Again, probably not enough, if there is a possibility of two people in the shop at once. Two 30A 240V, or one each 20A and 30A, is better.
Good idea. Lights should never be on the same circuit as the receptacles that power your machines. Example: the first time I used my table saw after moving into our current house (workshop in basement), I unknowingly plugged it into a receptacle on the same 15A circuit as the overhead lights. The instant I turned it on, the fluorescent lights dimmed to the approximate brightness of a birthday candle. NOT a good thing.
You may in time decide that a 240V dust collector would serve your needs better. So anticipate that need, and run *both* 120V and 240V circuits.
OK, wait a second here. Ceiling-mounted units are dust *filters*, not collectors. You really should have one of *each* IMO. (That subject has been beaten to death in this ng. Check Google for all the gory details.)
Four circuits is not enough IMO -- you can *never* have "enough". Yes, the
220/240V line is necessary. Having the lights on a separate circuit is not required by Code, but as I noted above it's sure a good idea.
My shop contains a table saw, dust collector, shaper, lathe (all 240V), bandsaw, radial arm saw, drill press, belt/disc sander, spindle sander, jointer, grinder, planer, mortiser, scroll saw, air filter, two exhaust fans, and a variety of portable power tools (all 120V). SWMBO and the kids (15 and
12) are woodworkers too, so it's not unusual that we have the dust collector, the air filter, and two or three machines running at once.
We have six circuits in the shop:
The lathe and the dust collector share a 20A 240V circuit.
The table saw and shaper share a 30A 240V circuit.
Bandsaw, drill press, air filter, scroll saw, and mortiser share a 20A 120V circuit.
Radial arm saw, jointer, and planer share a 20A 120V circuit. (I know it seems that this overloads the circuit, but the shop is kinda small, and its layout prevents the use of more than one of these at a time.) The grinder and sanders are on this circuit as well.
Lights are on a 15A 120V circuit.
Exhaust fans are on a 20A 120V circuit.
Portable tools usually get plugged into the same circuit as the air filter. sometimes the same circuit as the lights.
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Save the baby humans - stop partial-birth abortion NOW
There may be something in some locale where the IBEW has a strangle hold on the code officials but there is nothing in the NEC about this.
One thing that wasn't mentioned but may be implied. If these circuits are exposed, they should be in conduit. I know some AHJs are fairly lax in providing physical protection and allow Romex on running boards in utility areas. As an inspector I would see a wood shop, where you are handling large pieces of lumber, as a place requiring physical protection for the wiring. If this shop has a concrete floor, some AHJs might ask for GFCI protection in the 15 & 20a 120v receptacle circuits. (citing the same dangers you have in a garage or basement) That would be a stretch tho.
I have two circuits for lights (there's a little more than lights on these circuits, including garage door openers) and found it very convenient to have THREE switches for the lights, three banks of fluorescents. Means I can turn on some, most, or all, depending on what I'm doing. Didn't see the advantage of turning on all nine 2-bulb, 4-foot, fixtures just to fetch a screwdriver or somesuch.
Oh, and earlier I mentioned the number of circuits I have in my garage/workshop but overlooked another circuit for my 10,000BTU window air conditioner [gloat!]. On recent
100+ degree days (Wednesday, Dallas/Fort Worth had a record 109 for the date!) my shop was a comfy 77. Helps to turn the A/C on in the morning, when the ambient is 80+/-, and to have insulated the walls and garage doors (my ceiling, though, is still just a 1/2" layer of drywall, no insulation in the attic).
I tend to believe what my electrician, who has 50+ years of experience, and the city electrical inspector tell me, as far as what is required. :)
Locale is in the suburbs, outside of Chicago.
'Standard' here is BOCA building code (not NEC), 1997, with two lines of 'over- rides'. One forbids any new aluminium wire, and I don't remember, off hand, what the other one is.
Circuits above 20A capacity, *are* limited to single outlet. I was planning to put 30A circuits in my new kitchen, so I could have 2 1500 watt devices in use on a common circuit. No can do, so I've got 6 circuits worth of kitchen outlets instead.
12 ga is rated for 20A. This is adequate for a 'true' 3 HP load at 120V, or 6 HP at 240.
Assuming, as well, that you're not using anything bigger than 20A breakers,
If you have _really_ long runs, it's recommended to go one size larger than needed. Going 'larger than needed' also cuts down on the losses in the wiring. The cost difference between 12 ga, and 10 ga, is relatively small, and -- especially if you're doing the work yourself -- the labor cost is essentially unchanged.
I think I made the disclaimer about any place where the IBEW has a choke hold on the politians. Chicago is the prototype. #2 is New York City. Most of the country is on the NEC. Florida took the extra step to say the whole state is on the unamended NEC in their unified building code.
You couldn't do that in the NEC either. It specifies that kitchen "small appliance circuits" (serving the countertop) SHALL be 120v 20a GFCI only. Where were you going to find kitchen appliances with NEMA 5-30 plugs? You also can't put a 5-15r or 5-20r on a 30a circuit.
Be sure you get receptacles listed for 10ga terminations. That isn't the 43 cent one. It is the ~$2 one, (commercial/spec grade) but you should be using them anyway in a shop. Your plugs will run cooler and last longer. Don't back stab the devices, Use the screws. Some back wired devices do use screw clamping, they are OK. Just not the spring type.
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