Electrical help: 20 amp vs 30 amp

[loutent]

I had an electrical question a few months ago about this, and got several varied responses - mainly because I did not have enough information I believe. Now I actually have something to work with!

I have a brand new Grizzly 1023SL sitting in the basement (almost) ready to plug in. I have a copper,10 gauge (3 wire - ground, neutral, hot) coming from a 30 amp (unused) breaker which used to power a water heater (now gas). Our house has 200 amp service and is less than 20 years old (just for reference).

Grizzly recommends 20 amp/220. Do I need to change out the 30 breaker for a 20? If I leave it as is, will I harm the magnetic switch or anything else?

Thanks for any input.

Lou

[Roger Shoaf]

Go ahead and use the circuit. The circuit breaker is there to protect your wires. Your saw probably has an overload cutout on the motor.

Plugging your saw into a bigger circuit is like plugging a night light into a circuit that could power a toaster. No problem.

[LRod]

Roger's analogy is right. You don't sweat running your electric shaver on that 20A bathroom breaker, do you?

The other thing is make sure your terms are straight when you're describing your situation. You actually have a copper, 10 gauge (3 wire - ground, hot,, hot) coming from a 30 amp (unused) breaker which used to power a water heater (now gas). The fact that it used to power a water heater tells us it's a 240V circuit protected by a 30A breaker, thus the wires are hot, hot, ground. There is no neutral in a

240V circuit (North America).

- - LRod

Master Woodbutcher and seasoned termite

Shamelessly whoring my website since 1999

[Slowhand]

Use the 30 amp. Also, the power would be hot, hot, ground and NOT neutral, hot, ground. SH - The "used to wire houses" woodworker

[BAF]

Lou,

Sounds like you're confusing 110 with 220

To run your Griz Table Saw (I have the 1023Z) you need to add a 220 breaker (looks like 2 breakers in 1 and takes up 2 slots) to you panel and then have a 4 wire cable (Neutral, ground, 110 Phase A, 110 Phase B) run to the saw.

The gauge of the wire is determined by the distance the saw is from the panel and the amount of current it will draw (in your case 20 Amps). There's a formula for this but I don't have it handy so you should really have someone who knows what they're doing (electrician?) help you if you have any doubt about doing it yourself!

Good Luck

BAF

Woodworking Business Apprentice Program

[Leon]

Grizzly is probably referring to a minimum vs. an exact recommendation. Use it. I have my TS sharing a 50 amp circuit with a clothes dryer. Like Roger has indicated, the 20 amp breaker is not to protect you saw.

[toller]

You "can" do it, as long as you use a 30a plug and outlet.

Personally I would do the whole thing as 20a. Code only requires the breaker to protect the house wiring, but it is nice when it protects the machine wiring also. I bet when you compare 20a outlet/plugs to 30a, it is actually cheaper to replace the breaker.

[Leon]

With that in mind, and I agree about ground, hot, hot on a 3 wire set up. Many newer homes with 220 have 4 wires, 1 being ground. What do you call the other 3?

[Duane Bozarth]

...

Don't think that's code unless you're using the dryer outlet or the saw, not both?

[DJ Delorie]

There can be, it's a 4-wire circuit (black hot, red hot, white neutral, bare ground) used for multi-voltage appliances like ovens and dryers (240 for heat, 120 for lights, etc).

But a 3-wire 240 doesn't have a neutral. Or at least, it isn't

*supposed* to have a neutral. Circuits wired for 240v without a neutral *should* have the white wire tagged with red tape or something to indicate that it's not a neutral.

[TeamCasa]

Lou, This sounds like a 110v Circuit. You need 220V for that saw. Change the single pole (assumed) 30A 110V breaker with a dual pole breaker (20A -

220V).

Change or tag/lable the white wire as your second leg hot and you're good to go.

Dave

[Slowhand]

Hot, Hot, Neutral, Ground I have the 4 wire running to my table saw. Of which I branched off and created a duplex 110 recepticle where the neutral was needed. SH

[Leon]

Perhaps. Most of the time it is one or the other but both together is still about 12 amp under the circuit capacity IIRC.

[Leon]

"Slowhand"

[Roy Smith]

If you have ground/neutral/hot, it's 110, not 220. If you're trying to run a motor designed for 220, you need to have two hots (one from column A and one from column B). Typically you would do this by putting on a different receptacle and moving rewiring the panel side of the circuit to go to a double-pole breaker. Standard practice is to wrap red tape around the white wire at both ends to indicate that it's now a hot conductor.

Be that as it may, amperage requirements are *minimum* requirements. If the machine needs 20 amps, it's perfectly fine to plug it into a 30 amp circuit. It won't hurt the circuit and it won't hurt the machine.

You do need to make sure you've got the voltage right. Many motors can be configured to run on either 110 or 220 by moving a jumper or connecting to different terminals, but make sure you got it right. A mixup in either direction won't be good.

[CW]

Do yourself a favor. Ask a qualified electrician. The advice you get here will be good/bad/bullshit. Do you know how to tell which one is which? If you did, you wouldn't have to ask. Ask the professional, it's worth it.

[Duane Bozarth]

Don't think that's the issue...I think (US anyway) code only allows a single outlet on a dedicated circuit for the dryer...

Note I'm not saying it's an unsafe combination, just pointing out what might be an issue when (and, of course, if) you were to sell or other reason to need to ensure compliance...

[Roger Shoaf]

Technically I think Duane is correct here. The preferred way would be to have the circuit feed a sub-panel and have two circuits branch off from there. Keep this in mind if you are going to have your electrical inspected.

[Roger Shoaf]

If it can be configured to run on either, run it on the 220.

[Leon]

I see. I feared that when I install the extra outlet so it is mounted out side the wall and easily taken apart in the event I ever move. I have been gonna move since 1986. I'm still here LOL.