I’m mostly a hand tool guy but I’ve acquired an early 80’s Delta Unisaw. It’s wired for 220 but I don’t have an outlet wired for that. Should I rewire the saw to run on my garage outlet, or have an electrician upgrade an outlet to match the saw?
I foresee two main uses for the saw. First, it will be used for milling square edges on rough cut hardwood boards, mostly around 4/4 thickness but occasionally up to 8/4 after jointing and planing the faces and other edge. Secondly, I’ll use it to create accurate jigs for my hand tool workbench, such “Mike Pekovich’s Go-To Workholding Jigs.”
So, outlet upgrade or saw wiring downgrade? (If in fact it would be a “downgrade”).
Replies
I don't believe there is a way to "upgrade" a 110v outlet to 220v. To get 220, you need to run an appropriate wire from the breaker box to the outlet location. You also need room for the 220 breaker in the breaker box -- 2 slots. If it is not outrageous to run the new wire, a new 220 outlet is what you want to do.
To run on 110, you need to check the motor size and amp rating on its label. Your circuit is probably rated for 20 amps. If the motor is rated anywhere close to that (above 15 amps) at 110, you will not be happy with running it on 110, as you can trip the circuit breaker (or worse, burn out the motor) when it starts to bog down. If it came with a smaller motor than the max, it might work.
Thanks! Yes, running a new wire is what I meant. I had to do the same recently for an AC replacement and I think I paid about $200 for the work to be done. I'll check the motor as you described!
Check your garage outlet. Not all garage circuits are 20 amp. Many are 15 amps which might not be sufficient for the saw's motor, especially if you already have other outlets on the same circuit that may at least occasionally be in use at the same time. A new 220V circuit may be useful for other tools in the future if your garage is your shop.
I would change your outlet to 220v. You likely have a 3 belt 3hp motor which is fantastic. To change from 220v to 110v on your motor you will double the current draw, which I’m pretty sure would exceed the existing outlets capacity. Check the amp load on the motor to verify its draw at 220.
Mine is 25 years old, runs on 220 / 15A 14/2 wire circuit ( inspected and approved. Your plug should have the two flat prongs in a horizontal plane. This indicates a 220v 15a circuit. If one is vertical you would require a 20a circuit with 12g wire.
Your electrician, given enough slack in your box and a spare breaker slot, should be able to rewire the box to have the white lead on 1 breaker, black on another (balanced across your incoming feed). Change the outlet to a 15a 220v. Very easy if you have the space and a bit extra wire in the box.
Thanks! I'll take a look at it tonight to see what I've got.
What HP motor?
If you have the option rewire the outlet. 8/4 hardwood will NOT be fun on a 110V saw. While you're pulling wire pull an extra 220 leg for your next upgrade and just leave it as dead-ends on both sides, that's the hard part.
Agreed. My saw starts up faster and runs cooler on 220.
An old Unisaw.. 220 absolutely!
Go to 220 if it’s possible. Not just for the table saw, but any future tool you may pick up. Only having 110 greatly limits your options.
If it’s 3 hp such as my Unisaw, on a 120V outlet you will need 30 amps so unless the wiring from the electrical box to the outlet is #12 which I doubt, you will need to run a new circuit so might as well run a 240 circuit and keep the motor.
Small correction Gulfstar, here in the US 10 gauge wire is required for 30 A service. This is even less likely to be what is installed, but 12 gauge has been the required wire to use for 120v outlets for the better part of 2 decades or maybe longer and is rated for 20A and is likely the wire in place.
This is probably true but with LED's, low power TV's and other things, the power (current) load is now lower. I think with a 3 HP saw at 220 volts, the max current is around 10 amps. I have 12 gauge in my shop for the saw and a 20 amp breaker, never had a problem. In reality the saw doesn't use 3 hp most of the time. I also originally had 26 48" T-8 florescent bulbs split into two circuits. They were specked around 35 watts each so I used 14 gauge wire. When I replaced them with direct wire LED's, the power dropped to 16 watts per bulb and the current load is around 2 amps per circuit.
What works is one thing, what voids your insurance is another. Check the code, if it's not clear just put in the heavier gauge wire.
Ysu65
Current draw is relative to voltage. A tool that draws a peak 10 A on 240V will draw 20A on 120v and since the general rule is not exceed 85% of the breaker would require a 30A breaker and 10Ga wire.
Your set up is fine and legal only because it is on 220/240v. A 20A breaker and 12Ga wire would fail on 120v.
Wire size has nothing to do with voltage only amperage.
My bad, 30 amp is #10 in the great White North.
If you can afford the extra money, consider putting a subpanel in the garage. Rather than running a #12 cable back to the main panel, run a #6. When you want to run another circuit in the garage -- and you probably will -- the subpanel will be right there.
This is exactly what I did. My garage is detached and 50 ft from from the house. 60 amp sub-panel was worth every penny. The original 120v 15 amp circuit is still there but only for the lights the sub-panel does everything else. I put a switch in front of the panel. This turns off all machines.
I have to say that from the non-US part of the world, we tend to find these questions a bit bizarre.
It is what it is I guess, but 220/240V is far better if you can use it.
You get much lower power drop on a cable as current draw is less for the same power, you have more power more readily available and it's frankly madness not to have it available in a workshop.
Even with 240 at every outlet, I still at times find myself wishing for the raw power of 3-phase.
When you go 220, make sure that the wiring will handle 20A at each outlet - some of the better gear (say a true 4HP saw or planer) requires that much...
Well it all started with Edison and my guess is it was 100V. Actually 200V 3 wires that gets distributed in the residence as 100 between the live wires and the ground and 200V between the two live wires. They quickly realized increasing the voltage reduced the copper losses so through the years they increased t0 220, 230 and now 240V. The larger power consuming appliances are on 240V circuits for obvious reasons, in the shop we still require the 120V for smaller motors such as the portable tools but I would not imagine my 5hp planner on 120V. Higher voltages are reserved for commercial buildings, not allowed in residential so there you enter the 3 phases world with a max voltage of 480V in the US and 660V, 3ph in Canada. Note, your 120/240V motors are actually 120V even when supplied with 240, the wiring distributes the 240 in two 120V .
One last factor to consider, not all electric motors are "reconnectable" as either 120V or 240V. Those motors are hard wired to either one or the other voltage and can't be changed. So you may not have a choice of using 120V. This will be indicated on the motor nameplate. If you're not sure your electrician will be able to tell you.
But as others have said, given a choice the 240V would give much better performance and reliabilty.
The idea of a sub-panel in the workshop is also a very good plan.
220, 221. Whatever it takes.
I run my saw off my oven 240...
Tap into any 2 pole 240 breaker you have availible. Just make sure your wiring matches your breaker size regardless of the motor amp draw. Breakers protect wires not loads.
Also make sure you have a way to ensure the other paralell load wont run when your saw is....
I dont bake while i woodwork and its only me and the dog so...