220 V circuit breaker to two 110 V circuit breakers

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Old 05-13-11, 07:03 PM
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220 V circuit breaker to two 110 V circuit breakers

Hello everyone,

Is it possible to convert a 220 V circuit breaker into two 110 V circuit breakers. I believe I can do this with a three wire with ground. Install the red wire and black wire on the 220 V circuit breaker each one on its independent screw. The white wire and the ground wire then go to the ground. My only concern is if I exceed amperage on one of the circuits then both circuits will pop because they are connected. Perhaps there is a way to remove that connection that is typical with 220 V circuit breakers.
 
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Old 05-13-11, 07:20 PM
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In general it is allowed to do what you propose; this is called a multiwire branch circuit. There are some important details to get right though before it is safe and legal. Modern code may substantially restrict which rooms the MWBC can supply depending on the code version enforced in your region. What exactly do you plan to do with the circuit?

One of the disadvantages of a MWBC is that both poles will trip if either one overloads. There is no way around that.
 
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Old 05-13-11, 08:50 PM
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I mainly plan on using it for tools in a shop. The shop is the place were the wire will be run which is located in the garage. I actually have run wires like this before but at that time it wasn't connected to a 220 V circuit breaker but rather two independent 110 V circuit breakers. I thought there might be some problem because it is a 220 V circuit breaker. The place where I ran those first wires was in the garage as well. The 220 V circuit breaker at this time is not being used so why buy another one if I can just use this one. Much more economical this way. Thank you as always.
 
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Old 05-13-11, 09:20 PM
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Is this an attached garage or a detached garage? If it is detached and you already have circuit you can't run a second circuit.

Tech note: Nominal voltage in the US hasn't been 110/220v for many decades. Residential 1 is 120/240v.
 
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Old 05-13-11, 10:04 PM
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It is an attached garage. I am aware of the voltage coming into a residential home. I thought that people use 110 because of the fact that as electricity goes down the line it loses its voltage which is why light bulbs at the end of a circuit generally do not last as long as those closest. So essentially with that you could either say 110 or 120 and still be technically correct because your voltage isn't consistent throughout. But I guess in the olden days voltage coming into a home was 110 instead of 120. Who knew? Thanks for the lesson and help.
 
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Old 05-13-11, 11:35 PM
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Angry

Since it is an attached garage what you plan is ok but you must have GFCI protection on each 120v circuit after the split to 120v.

I thought that people use 110 because of the fact that as electricity goes down the line it loses its voltage
No, voltage should remain about the same.
which is why light bulbs at the end of a circuit generally do not last as long as those closest
Never heard that and it isn't true.
 
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Old 05-14-11, 08:01 AM
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My only concern is if I exceed amperage on one of the circuits then both circuits will pop because they are connected. Perhaps there is a way to remove that connection that is typical with 220 V circuit breakers
What hasn't been pointed out yet is that the 2008 NEC requires that you use a 2 pole breaker (240V circuit breaker) for a multi wire branch circuit so you don't want to remove the connection to convert the 2 pole breaker into two 1 pole breakers. Yes, both poles will trip if one is overloaded, but the code panel thought that to be much safer than just having one pole trip. What code do you fall under? If you don't know, try contacting your local building commission (AHJ). If you still don't want the connection on the 2 pole breaker and want to remove it, try looking locally for some 12-2/2 w/G romex which has two neutral conductors. Colors you'll find are black, white, red, white w/red stripe plus a bare ground. If you use 12-2/2 romex you can use two separate 1 pole breakers as you may have used in the past.
http://www.southwire.com/ProductCata...=prodcatsheet6
 
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Old 05-14-11, 11:07 AM
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Originally Posted by 951Michael View Post
which is why light bulbs at the end of a circuit generally do not last as long as those closest.
That's backwards anyway.. Reducing the voltage to a bulb makes it last longer. As for the voltage drop, there isn't anywhere near enough wire length inside a house to induce a noticeable voltage drop. You only run into this when say, running a circuit to a barn, dock, pool, etc that is hundreds of feet from the house. Even then, voltage drop is a function of the wire size, so as you increase the distance you increase the wire size to offset the drop.

Originally Posted by CasualJoe View Post
... so you don't want to remove the connection to convert the 2 pole breaker into two 1 pole breakers. ..... If you still don't want the connection on the 2 pole breaker and want to remove it ...
AFAIK there are no breakers that you can actually do this with because multipole breakers have an internal common trip mechanism. The handle tie is simply for identification purposes and common reset. Even with the handle tie removed, a trip condition on one pole will trip both breakers
 
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