110, 220, 208 Volt Electrical Outlet Question

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I recently move to a new home. One plug in the garage wasn't wired with an outlet yet. It appeared on the panel as "Heater" and has two breakers. I think it's what they call a 208 volt heater plug (why 208?) Are these common? Can I use it as a 220 instead (Table Saw)? There doesn't appear to be a neutral only two hots. I'm guessing 12 gauge wire. Thx.
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I'm surprised that there would be a 208 volt service in a residential area. The utility that serves your area would provide 220v and half of that is the 110v that is standard in the US. For you to have anything different would require a step-up or step-down transformer (in your case) somewhere in the circuit. Check around your circuit breaker panel for a transformer on the wires that run to the plug you mentioned. If there isn't any transformer than you probably don't have 208v. However, you may want an electrician check it out. Circuit breakers won't step-down the voltage. Hope this helps.
frank

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208 is just a generic name. In a regular US home that will have 240v on it (AKA 220,230). You can look here to see what it really is
http://www.quail.com/nema.cfm
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snipped-for-privacy@aol.com (Greg) writes:

208 is anything but a generic name.
And it is entirely possible that some newer residential environments (especially multifamily homes) will have 208 service (which is _NOT_ the same as 220).
Don't post if you don't know.
scott
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It's two, 110~120's 15amps each and a ground.What's it for. Can I use it for a 220 table saw? Why no neutral? Thx.
(Greg) writes:

it (AKA

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Because you don't need one. 220V is two 110 legs....180 degrees out of phase. If you measured the voltage between either leg and neutral it would be 110V, but between both hot legs, it is 220V. Some appliances (like a dryer) require a neutral because some functions of the appliance (like the light) run on 110V. On the inside, a dryer is really a hybrid device.
Basic motors and heater are not hybrids; they don't need 110, therefore do not need a neutral.
Steve
(Greg) writes:

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On Wed, 4 Feb 2004 15:34:33 -0500, "Stephen M"

If I remember correctly, 208 volts is derived from two legs of a 120 volt, three phase supply. 208 = (120) (sqrt 3)
Joe
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for
Table saw don't ordinarily need a neutral, though the magnetic switch on mine does.(don't ask...) Two 120v wires can mean either 240v or 208v.
It would be very unusual to have 208v in a home, so it is probably 240v and is probably okay; but if it really is 208v you could burn the motor out. It is prudent to test it with a voltmeter and/or check with your utility to make certain.
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Toller wrote:

It will need a neutral if it also has a 110V device (such as a light bulb, for example).
Also I read somewhere that some new regs require 4-conductor wiring for all 220V outlets. However, I do not have a reliable source for that statement (nor do I know if it applied to just outlets or devices as well), take it as a rumor I suppose.
--
gabriel

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all
You only need 4 wires (3 conductors and a ground) if you have something that actually needs the neutral; such as a table saw with a 120v light bulb (?). Otherwise you only need 3 wires.
My dryer puts 7a into the ground (technically an "uninsulated neutral") which is a little spooky, but I have never heard of anyone having a problem; which could result if the neutral connection broke somehow and energized the case.
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Do you mean the safety 'green' wire? That's highly dangerous as well as illegal... could put power anywhere because of the water pipe grounding. There was a case here of some ones house going on fire because of excess ground current in a neighbors house!! For some reason, probably linked to the electric company location of their ground, the current found its best path thru the ground leads of the next house, and the attic caught on fire where the leads entered the house.
I talked to a company engineer, and he said they detected 70 amperes of 'lost' ground current in one of their feeds!!
You should re-wire it with the proper 4 wire connector...
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gabriel wrote:

It all depends on the AHJ. 220 V receps inside house need a neutral, 220 outside such as in a garage don't need neutral per the building inspector here in Phoenix and that only covers new installations. Existing 220V still only requires 2 hot and a ground.
Gary
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It tests around 115 on each side therefore not 208. Someone I know called it a 208, they were wrong. Thx.

and
to
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it
That is not adequate; 208a will test about 115v to ground on each also. You have to test hot to hot.
208v has two 120v hots 120 degrees out of phase. Between them they are 208v. 240v has two 120v hots 180 degrees out of phase. Between them they are 240v. (strictly speaking they are not out of phase, but it is close enough to the truth for this purpose.)
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They test at around 240

called
You
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Out of phase is as good and reasonable a description as anything else.
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If I'm not mistaken you can't have true 208 without 3 phase power, i.e 3 hots coming into your house. Most US residences will have 2 hots which is correctly referred to as single phase 220 service. This is what you've got. probably a heater or a dryer.
Any electricians confirm this?
(Greg) writes:

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It's at ground level next to my garage door. It's gotta be a heater at 220 V
(Greg) writes:

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You can have true 208V single phase without 3 phase power being supplied. Line-to-Line is 208 V and Line to Neutral is 120 V.
However, in my experience, it is highly unusual to have 3 phase power supplied to a residence. The most common US residential service is 120/240.
(Greg) writes:

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Does it matter that the breakers are both on the left hand side of the panel? Not one on the left and one on the right? Does that mean both lines are coming in to the plug on the same phase? And not 180 degrees out?
(Greg) writes:

on
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