Creating a 220 circuit?

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On Sat, 15 Nov 2003 04:29:44 GMT, "Wade Lippman"

Let's assume the guy that ran the circuits to the garage knew a LITTLE bit about electricity.
Now...let's assume that even YOU know a little bit about electricity.
Now...takin' into account what you know about electricity (and if you get this wrong, BTW, we won't hold it against you)...
...would you run 2 circuits off the SAME leg? Or would you run 2 circuits...one from EACH leg?
Remember...your answer has NO bearing on what he actually has there. But MOST garages have no need for 2 20A. circuits. One circuit alone can usually handle the garage door opener, lights, etc.
So...TWO circuits MIGHT have been a plan for some 220 stuff...but not necessarily.
My last post on this to you. Just seems like you've got a hair up your ass again.
Have a nice week...
Trent
Fighting for peace is like screwing for virginity!
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Yes, and you MIGHT be a normal person just pretending to be an dumb jerk. But you aren't, and his circuits aren't "a plan for some 220 stuff." I take back what I said about your imagination; that is really wild!

And just because you put things up your ass, you can't assume everyone else does.
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I'd do it only if it was convenient and it made sense to do it for balancing loads across legs. New construction in cookie-cutter houses, they'd not pay attention. If they were part of seperate revisions, no, wouldn't pay attention. Under normal circumstances, it'd be mostly a matter of luck.

Codes like having major motors on their own circuit. If it was a two door garage, two circuits QED. There is also some code requirements about per-bay ampacity requirements up here (block heaters etc).

Absolutely NOT.
Unless the two circuits were in the same cable, 220V is _not_ a legal "future" plan, and thus is irrelevant. Period.
IF the OP's 220V device was within the ampacity limit of the existing 12ga wire, the best and cheapest way to legally get 220V is to convert just one of the 120V circuits to 220V (swap a dual breaker in place of the single, wire the white wire to the other breaker. Mark both ends of the white wire with tape or whatever. Still have the other 120V circuit.
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Chris Lewis, Una confibula non set est
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On 16 Nov 2003 00:25:38 GMT, snipped-for-privacy@nortelnetworks.com (Chris Lewis) wrote:

Cable? I guess I'm not following. I'm talking about running 3 wires + ground thru conduit. Is that what yer talkin' about?

We don't even know where those 20A. BREAKERS are? lol
Have a nice week...
Trent
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The OP appeared to be talking about a pre-existing cable installation, not conduit.
Wires sharing conduit count as "cable" in this context. But, if you were to combine two 120V circuits (which have one neutral apiece) in this way, you'd have to common the neutral (abandoning one of them).

In the breaker panel one would assume. Where else?
If you were converting a 120V circuit to 220V, you can often get away with swapping an existing single breaker with a half-width dual, no panel shuffling required.
--
Chris Lewis, Una confibula non set est
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On 20 Nov 2003 21:18:34 GMT, snipped-for-privacy@nortelnetworks.com (Chris Lewis) wrote:

I always get a kick out of threads that go the way this one has gone...creating all kinds of assumptions.
The 'appeared' in this case seems to be one of those instances. It didn't 'appear' to ME whether there was cable run out there...or wires in a conduit. I've seen a lot of both type of installations.

Yer right, of course...or I hope yer right. I wonder where the breaker box is...that's what I *REALLY* meant to ask. It could be in either location...or both.
Have a nice week...
Trent
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only if the 2 breakers are on different phases. you get 3 wires from the utility, one ground and 2 hot ones.
if both breakers are on the same hot wire, you can't do 220.
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Re: Creating a 220 circuit? Group: alt.home.repair Date: Thu, Nov 13, 2003, 6:25pm From: snipped-for-privacy@jj.com (jj)
I would like a 220 circuit to use with a 4500 watt heating element.I have two separate 110 circuits in my garage,each on GFCI and each with a 20 amp breaker.Can I run a black wire from each of them,a white wire from one and a ground from the other and create a 220 circuit in a separate receptacle?If so,can I still use these "donor" receptacles as 110s when I am not using this new 220? only if the 2 breakers are on different phases. you get 3 wires from the utility, one ground and 2 hot ones. if both breakers are on the same hot wire, you can't do 220.
Just fcking great tell the guy how to get 220 from two seperate breakers really smart advice.
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I didnt' tell him how to do it, just that he can't simply take 2 black wires and make a 240V circuit.
if he wants to find out how to do it, he can easily find it on the web, it's not like it's a big secret.
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Well, 4500 watt would draw about 21 amps or so. There is a slight chance you could run them off the two twenties. But it would cost a pile of money for electric, and you woulnd't have enough left over to run any tools.
I'd pitch that idea in the scrap.
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he calculated with 220V as the original poster said, while you probably calculated with the real 240V voltage.
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voltage is 240 +-5%.
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Allowable voltage at the _panel_.
By the time it gets to the fixture, it could (allowably) be down another 6%. 220V is the _minimum_ code-permitted voltage at the device. That's where the "220" terminology comes from.
The 4500W is "worst case draw" under "allowable conditions", which with a resistive load will be 240V _plus_ 5%. Which means that under "average" conditions, the wattage will be less than 4500.
With an electric motor, it's the opposite. Max current is at _minimum_ allowable voltage while producing rated power.
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but I have always heard that wiring should be sized to have no more than a 3% drop. Comments?
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That's correct. But you're forgetting something. The panel may already be 5% lower than 240V. Which means that the "wire sizing for no more than 3% drop" from the panel to the outlet will get you close enough to 220V not to matter. In other words, the two "permissible" voltage drops when added together get you to 220V.
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Way back when, the poster said that a 4500w heater drew 21a at 220v.
A 4500w heater would have 12.8o resistance, so it's draw at 220v is 17a. Yes?
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This is how I figure it:
I believe the 4500W is computed at max permissible voltage: 240V + 5% = 252V This leads to a current of 17.86A, 14.12ohms.
Minimum operating voltage (worst-case total voltage drop) is 220V. Assuming resistance the same (it will be lower due to lower operating temperature), that's 15.6A. Which is 3433W. But that ignores the temperature coefficient of the heater element - true power and current would be somewhat higher, how much higher depends on the unit.
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Methinks the difference between the 19 and 21 relates to what number you use as a divisor. If you use 220, you get about 21
Watts/volts =amps
Stan
On Fri, 14 Nov 2003 02:25:51 GMT, "Wade Lippman"

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no, using the 80% rule for constant loads, he would need a breaker and wires rated for at least 25 amps (which don't exist, so go for 30 amps)
heating is done with double 20A breakers and special wires for electric heaters, and you can't go above 3800 watts per heater (80% of max)
as far as heating is concerned, I'd really go with an electrician since there's a risk of fire. it's not the same as creating another outlet or running a wire for a new light.
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