Electrical help: 20 amp vs 30 amp

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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
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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.
--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
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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
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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?
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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
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That's what I was thinking.
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All that is true, and I'm sure as an old sparky you remember when a 240V circuit was just the two hots; the ground wire is a relatively new (40 or 50 years?) requirement.
In any event, I'm also sure you will agree that in a 240V circuit that will supply only a motor or a heater, there won't be any neutral because there is no neutral in a 240V circuit.
Now I am fully aware that dryer circuits are now required to be four wire, that one may no longer use the ground for the neutral path needed for the 120V parts of a dryer circuit which the NEC permitted as a special use. But that's an exception. I think that may also be an exception in range circuits, but for water heaters, table saws, planers, jointers, dust collectors, ACs, etc., all that's required is three (and electrically, all that's needed is two), and neutral isn't one of them.
Your example of the 120V receptacle is simply a variation of a multi wire circuit which looks just like a 240V circuit everywhere along the circuit except at the loads. But a neutral IS needed in a multiwire circuit. It isn't in a 240V circuit excepting the dryer/range applications.
- - LRod
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So do you still maintain, There is no neutral in a 240V circuit (North America)?

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On Sat, 08 Jan 2005 05:13:29 GMT, "Leon"

What I'm trying to say (and apparently unsuccesfully) is that *electrically* there is no neutral or need for a neutral in a 240V circuit in North America. All that's needed for a 240V load to work is the two hots. Period.
The ground is a safety requirement that was added to the NEC several years ago. It isn't electrically required for a strictly 240V load to work (North America). In some other locations with solely 240V service, it may be that they have a 240V and a neutral. Probably not, but I don't know. But in North America, that's not how 240V works.
The "neutral" is a safety requirement that was added to the NEC recently to alleviate the anomalous situation (elsewhere prohibited) in dryers and ranges where the ground had previously been permitted to perform the duties of a neutral as in a multi wire (2 x 120V/shared neutral) circuit. That is, there were some 120V things going on in the machine that is fed by a 240V circuit.
So, in the strictest sense of the words, yes I suppose you could say that there is a neutral in [certain] 240V circuits (North America). But it's not electrically necessary in order to run most 240V loads.
- - LRod
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I am not disagreeing with that statement, "There is no need for a Neutral in a 240V circuit in N America." But some what recently there is that 4th wire being used. My house does not have the 4th but the newer ones do. Previousely you indicated that there was NO Neutral in a 240 circuit. I was just trying to clarifiy what the 4th wire was exactly.
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On Sat, 08 Jan 2005 20:46:07 GMT, "Leon"

It's a neutral. That doesn't contradict my original statement given in my previous post. It performs a function that most closely resembles a multiwire circuit.
The best way to think of all of this is to not think of "neutral" and "240V" in the same breath (I think I may have mixed a metaphor there).
"Neutral" only has meaning at 120V. If there is a neutral wire in a 240V circuit it's because there is some 120V load in the appliance that's being powered. NEC no longer permits the ground wire to perform that function (and rightly so) in new construction. That's why you see 4 wire "240V" circuits.
- - LRod
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Ok, I think I am see what you are saying now....Thanks
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"LRod" wrote:

"Neutral" can be a very confusing term.
Rather than neutral, think of it as an "above ground return".
It can be a current carrying conductor and should be treated as such.
"Earth Ground", usually the green wire in the electrical world, is a totally different issue.
HTH
Lew
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If you're confused by the term "neutral", hire an electrician.

Using the word "ground" to describe the center tap of a transformer is misleading. It is the neutral tap of a multi-tap transformer. It is grounded at some point, but it is not ground, nor is it a "return".
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DJ Delorie wrote:

Could probably find one of my students.

Go back and reread the post. After that go back and enroll again in EE101, the power option.
Lew
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Or the guys who wired my house :-P

Sorry, already have an EE degree. I even know how to make transformers from scratch.
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wrote:

I always thought you made transformers from copper and iron :-)
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You buy enough copper you'll need plenty of scratch.
- - LRod
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just remember watts / volts = amps so a 600 watts runing 240 volts = 2.5 amps and so on. you dont need a neutral but I would run a case ground.

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wrote:

You also should not post in electrical threads. The amount of current draw in a circuit has ABSOLUTELY NOTHING to do with whether a circuit "needs" a neurtral or not.
Neutrals are a part of a 120V circuit. They are not an electrically necessary part of a 240V circuit.
A "case ground", as you and no one else would put it, has been a requirement for a long time, but as a safety item; it is not electrically necessary.
- - LRod
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