# Electrical help: 20 amp vs 30 amp

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• posted on January 8, 2005, 7:14 pm

Hey, I'm not old. (38). ;-) As long as I've been sparkin (wired my first house in 1992), it's been two hots and a ground.
I have a buddy who's a electrical contractor who pretty much taught me enough to be dangerous. I'm still not sure why electricity works the way it does. I just do what I've been taught. SH
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<%-name%>
• posted on January 7, 2005, 11:19 pm

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.
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<%-name%>
• posted on January 7, 2005, 10:58 pm

Use the 30 amp. Also, the power would be hot, hot, ground and NOT neutral, hot, ground. SH - The "used to wire houses" woodworker
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<%-name%>
• posted on January 7, 2005, 10:58 pm
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
size=2>...</FONT></DIV><FONT size=2>&gt;I had an electrical&nbsp; question a few months ago about this, and got<BR>&gt; several varied responses - mainly because I did not have enough<BR>&gt; information I believe. Now I actually have something to<BR>&gt; work with!<BR>&gt; <BR>&gt; I have a brand new Grizzly 1023SL sitting in the basement<BR>&gt; (almost) ready to plug in. I have a copper,10 gauge (3 wire - ground,<BR>&gt; neutral, hot) coming from a 30 amp (unused) breaker which used to<BR>&gt; power a water heater (now gas). Our house has 200 amp service and<BR>&gt; is less than 20 years old (just for reference).<BR>&gt; <BR>&gt; Grizzly recommends 20 amp/220. Do I need to change<BR>&gt; out the 30 breaker for a 20? If I leave it as is, will I<BR>&gt; harm the magnetic switch or anything else?<BR>&gt; <BR>&gt; Thanks for any input.<BR>&gt; <BR>&gt; Lou</FONT></BODY></HTML>
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<%-name%>
• posted on January 8, 2005, 4:47 pm
wrote:

Please turn off HTML before you post again. Thank you.

No reason at all to think that. He has a 220V table saw that needs a (minimum) 20A circuit, and he's asking if it's OK to hook it up to a 30A 220V breaker. No mention of 110 anywhere.

No he doesn't. He already has a 220 breaker.

Wrong. He needs a three-wire cable (hot, hot, and ground). The table saw, being a 220V device, doesn't need the neutral.

Wrong again. The gauge of the wire is determined principally by the rating of the breaker protecting it. For the 30A breaker that the OP says he has, the *minimum* wire size is 10ga copper (or 8ga aluminum) regardless of the distance from the breaker to the equipment. In residential applications such as the OP's, it is *highly* unlikely that the load can be far enough away from the breaker as to require a heavier gauge of circuit conductor.

Well, at least *that* is good advice.
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
Get a copy of my NEW AND IMPROVED TrollFilter for NewsProxy/Nfilter by sending email to autoresponder at filterinfo-at-milmac-dot-com You must use your REAL email address to get a response.
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<%-name%>
• posted on January 10, 2005, 3:45 pm
Man, if the OP thinks he had confilicting advice last time, what is he going to think now?
--

Larry Wasserman Baltimore, Maryland
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<%-name%>
• posted on January 7, 2005, 11:04 pm

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.
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<%-name%>
• posted on January 7, 2005, 11:11 pm
Leon wrote:

...
Don't think that's code unless you're using the dryer outlet or the saw, not both?
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<%-name%>
• posted on January 8, 2005, 12:01 am

Perhaps. Most of the time it is one or the other but both together is still about 12 amp under the circuit capacity IIRC.
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<%-name%>
• posted on January 8, 2005, 1:38 am
Leon wrote:

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...
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<%-name%>
• posted on January 8, 2005, 2:13 am

still
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

About the time I had mastered getting the toothpaste back in the tube, then
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<%-name%>
• posted on January 8, 2005, 2:52 am

Yeah I agree and did not make the install modification permanent in the event that I do ever move or have an inspection.
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<%-name%>
• posted on January 8, 2005, 2:51 am

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.
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<%-name%>
• posted on January 8, 2005, 2:48 pm
Leon wrote:

Of course, the other outlet needs to be wired to the same ampacity of the breaker to protect that wiring as well as the original...otherwise, one would have an unsafe condition in that section of the circuit. I was agreeing w/ the load of the saw as not being an excessive load w/ the dryer for short periods, especially since one has to be there to operate it...
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<%-name%>
• posted on January 8, 2005, 3:04 pm

Yes, and it is. I think we are seeing eye to eye here Duane... Thank you.
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<%-name%>
• posted on January 7, 2005, 11:08 pm
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.
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<%-name%>
• posted on January 8, 2005, 12:01 am
Lou said:

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
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<%-name%>
• posted on January 8, 2005, 3:09 am

Whats the last water heater you saw connected to a 30a 120v line? It has to be 240v; he just thought the 2nd hot was a neutral. (However, it does suggest he shouldn't be doing any of this himself.)
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<%-name%>
• posted on January 8, 2005, 5:14 am

Actually I saw one 5 years ago on a small 10 gallon tank.
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<%-name%>
• posted on January 8, 2005, 4:50 pm

Not if it used to power a water heater like he said. He's probably looking at black-white-bare and thinking he's seeing hot-neutral-ground, when in fact it's really hot-hot-ground on a 220V circuit.
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
Get a copy of my NEW AND IMPROVED TrollFilter for NewsProxy/Nfilter by sending email to autoresponder at filterinfo-at-milmac-dot-com You must use your REAL email address to get a response.