240 V breaker/phase question

I am getting ready to install a 2000W 240V heater that will be supllied by a 30A subpanel running off the main panel (10/3 w/g).
I have a "1/2 size" dual 15A breaker I pulled out of the main panel a while ago, but was thinking I will need a full size breaker, so that the two 120V suppies to the heater will be running off different phases in the subpanel. The way the 1/2 size breaker feeds off the main panel is through only one "side", so that both 120V to the heater will be essentially supplied by the same 120V feed from the main panel, so the two 120Vs to the heater will be "in phase". If I use a standard size breaker, then it will bridge the two sides of the subpanel, so it will supply the heater with two 120V from different phases. Is this a correct assumption?
thx
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On 31 Oct 2005 08:55:32 -0800, snipped-for-privacy@hotmail.com wrote:

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this is Turtle.
Yes the above will work but you just broke the NEC code as to having a 240 volt service breaker being joined together if one trips the other will go with it. This only depends on how safe you want to be or does being in code matter to you.
TURTLE
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I am not sure what you mean. At the main panel, my 30A breakers are tied. As I understood it, this IS code. The breakers need to be tied together. At the subpanel, the two 15A breakers are also TIED, since they will feed the same device.
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: >I am getting ready to install a 2000W 240V heater that will be supllied : > by a 30A subpanel running off the main panel (10/3 w/g). : > : > I have a "1/2 size" dual 15A breaker I pulled out of the main panel a : > while ago, but was thinking I will need a full size breaker, so that : > the two 120V suppies to the heater will be running off different phases : > in the subpanel. The way the 1/2 size breaker feeds off the main panel : > is through only one "side", so that both 120V to the heater will be : > essentially supplied by the same 120V feed from the main panel, so the : > two 120Vs to the heater will be "in phase". If I use a standard size : > breaker, then it will bridge the two sides of the subpanel, so it will : > supply the heater with two 120V from different phases. Is this a : > correct assumption? : > : > thx : > : : this is Turtle. : : Yes the above will work but you just broke the NEC code as to having a 240 volt : service breaker being joined together if one trips the other will go with it. : This only depends on how safe you want to be or does being in code matter to : you. : : TURTLE
HUH? What are you talking about? If it's a split-phase system, the breakers are required to be ganged. Flip one, they both flip. Did I fall asleep or something?
Regards, Pop
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This is Turtle.
i read it as he was going to use a single breaker and the side off another double breaker.
Yes you feel a sleep for you did not read into what i read.
TURTLE
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Your question is a little unclear to me. My answer would be any 240V appliance must be fed by the proper size double breaker so that if one leg trips, they both trip or if you turn off the breaker to replace the plug for example, you will be turning off both legs.

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using two full size breakers next to each other? Yes, they will catch both sides.
When I put my last 240 breaker in, I got a duplex breaker. It has 4 half size breakers. The top and bottom ones are tied to form a 240 breaker, and the middle two are joined to form a second 240 breaker. Don't know if you can do that, but if you are short of space...
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Off of a 30 amp sub? 2000/240 = 8.33 amps You can run this heater off of a 15 or 20 amp double pole breaker.

Partially correct, but you will not find 2 phases in your panel unless you have a really weird service. You will likely have a split single phase 240 volts, and you'll have to be tapping both sides of the split to get the 240 volts.

If you are wiring a 240 volt appliance, then you won't want to wire up the load wires to what would essentially be zero volts.

Semi-correct... First, research the definition of electrical phase. Then realize that you do not have 2 phases in your panel. You have a single split phase 240 system with a center-tapped grounded neutral for 115 volt appliances.

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