Yet another shop power question

[lrogers]

I was thinking this week (very dangerous stuff) about the wiring for the new shop. When I wired my current shop, I used 12 gauge wire and 20 amp breakers for the 110v stuff and 10 gauge wire and a 30 amp breaker for the 220 circuit.
Since the new shop is going to be much bigger and built to last for the rest of my wood working days, I thought about running 10 gauge wire to the saw and at least a few of the other circuits. The thought being that if the need arose at a later date for a 220 circuit, I could just change out the breaker and outlet giving me the maximum in versatility with a minimum of fuss.
Is my thinking sound here?

[Nick Keenan]

I'm generally not a big fan of trying to outsmart the future. As Louis Mayer said, nothing is harder to predict than the future. Unless there is some construction feature that will make future wiring changes inordinately difficult, I think you will be happiest if you build it for your needs today and change it when the time comes.

That said, I would think the maximum in flexibility would be to run 12/3 at 220v and split it into two 110v outlets at the junction box. For now you've got 20A on two separate circuits side-by-side, so you can run two power hungry tools right next to each other. This is a basic circuit that any electrician will immediately understand. In the future you can change it to 220v by changing the outlet (*) and you've got 4800 watts, over 6HP of power. Once you get much beyond 20A you can no longer size wire by simple rules of thumb, and factors like the length and positioning of the wire become important, so you really should have the device there when you run the circuit.

One consideration is that 110v is usually run with the outlets daisy-chained, which is a no-no for 220v, where you want one outlet per circuit.

* Note: If you want to make a circuit switchable between 220v and 110v, you can use a tied circuit breaker either way. However, it limits the usefulness of the 110v circuits as both will shut off when one trips the breaker. If you want to put the two legs on separate breakers then you need to change breakers to go to 220v. Either way it's pretty cheap and easy.

Nick

[lrogers]

Thanks for that info Nick. When I wired the current shop, only the light circuit was daisy chained, all others were one outlet per circuit. This has worked well, so that's also the plan for the new shop.
I've got plenty of time to plan the new shop so when it's built, it will be right.

[stewchi]

Using conduit with THHN or other spooled wire (IE not ROMEX) makes it very easy to upgrade the wire in the future. Pulling wire through conduit is pretty easy.
I would guess however you probably will not need to. The size of the wire is purely a factor of the current. 12 gauge is a good size for both 240V and 120V. The advantage of 240V is that you can have twice the power for the same current IE same wire size. This saves money (internal parts of motors, wire in the home etc). With a 20A 240V circuit you have 4800 watts of power, in comparison the BT3 uses about 1500 watts so unless you will have a bunch of machines 3 times the size (electrically) of the BT I would stick with 12 guage wire and 20A circuits for both 120V and 240V.

[LarryG]

Also, 10ga wire is a b*tch to work with since it's considerably heavier and less flexible than 12ga. Of course wiring a building is theoretically a one-time job but you don't have to struggle to hook up too many receptacles to 10ga before you start muttering under your breath and wishing it was 12ga.

[bolson]

If you plan your runs properly, it actually isn't that hard to go back and fish new wires. Especially if you leave the attic of your shop unfinished because they you can go up top, drill a hole in the top plate, cut a hole in the wall and pull a new wire. It is only hard to add circuits when you have to go through joists in a finished ceiling with finished rooms above.

If it were me I'd pull 12/2 and call it done. 12/2 is cheap especially if you buy in 250' rolls. 10/2 is about 2x the cost. You can run 12/2 as 220v circuits buy you can only limit the amps to 20amp 220V. This is how I wired my shop, you just have to mark the neutral as hot with electrical tape. Only 5 hp motors need more than 20amp and then you are usually dealing with a dedicated circuit anyway (compressors etc.) If you ever get a 5 hp TS or jointer (unlikely) you can then pull a couple of 30a 220v

My only recommendation is to overwire. I put a receptacle on about every stud. Yeah everyone who helped my drywall made fun of me, but I am never far away from a receptacle. Put in 2x the circuits you think you'll need and more outlets than you think you'll need, no body every says I have TOO MANY receptacles. Receptacles are about $3 each.

[Tom Miller]

I have a lot of 20A outlets daisy chained since these are meant to power the one-at-a-time tools. A double box of outlets (4 outlets) every 6 feet or so is good. I have several quad outlets like this that are full since the tools tended to cluster themselves (1: Band saw, table saw, router, lathe, 2: Drill press, jointer, planer, corded drill).

I'll ditto LarryG's remark about 10 gauge being a pain in the butt to work with. Also, you may find that 10 gauge won't fit your outlets, especially if you use the quick connect holes.

Regards,
Tom

[lrogers]

You guys are right on top of things. I went to the electric shop forman here at work and he said the exact same thing you all did!

Brad, you are so right about over wiring. I THOUGHT I had over wired the current shop, but now wish I had added a few more circuits.

Well, now that the power question has been resloved, I only have about a thousand more issues to clear up!
Last night I was talking with LOML about the new shop and she asked if I had a cost estimate yet. I told her that I had found a place on the web that would deliver a pre-fabbed shop that would take about 80 hours to assembly for $16K. When I revived her, I told her I expected the budget to be about $6-8k and she didn't bat an eye (didn't tell there may be a few over-runs)!

[bolson]

Larry,

I even did something a bit different. I made it so that every wall has 2-4 circuits

On the main machine wall I have 4 circuits. 2 220, 2 120. These are wired every other so you know the neighboring receptacle is on a different circuit. I also designed it such that if you need to separate the circuits, all you need to do is cap the wires in the middle of the run (or split the duplex receptacle in the middle) and pull a new wire to the opposite end of the run and the you have new circuits on the corners of the wall.

In all I MUCH prefer single duplex outlets on every other stud on different circuits than running double gangs every 2-4'. I was re-attaching my workbench to the wall last night and instead of running the drill on an extension cord, there was an outlet hand at every site I needed to put in a screw. It was the first time I have used a power drill without tripping over extension cords. Basially I designed my wiring to NOT have to use any extension cords.

Breakers are cheap and receptacles are cheap. The most expensive part of the install was the 6/3 cable to the sub and the sub itself.