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Using a 2-pole, 240v 20amp breaker, two 12-2 cables for 2 circuits

Using a 2-pole, 240v 20amp breaker, two 12-2 cables for 2 circuits

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  #1  
Old 01-11-06, 06:26 AM
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Using a 2-pole, 240v 20amp breaker, two 12-2 cables for 2 circuits

Panel box does not have any open single breaker slots, but does have an open 240 double slot.

Can a 2-pole 240 volt 20 amp breaker (double wide) be used for 2 separate circuits, with each circuit useing its own 12-2 with ground cable? The black wire from each cable would be connected to one of the hot screws. The whites to the neutral bar, and the grounds to the ground bar. If yes, then can each circuit have its own GFCI? Thanks.
 
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  #2  
Old 01-11-06, 07:14 AM
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Well first I will answer your question.

Yes, you can use a double pole breaker as two single pole breakers. Once you leave the panel with two separate 12-2 cables you can do whatever you like with them, including placing GFCI receptracles, etc on them. However, the breaker will trip with an overload on either circuit.

Now for the question. Why would you do this? Replace the 240 volt breaker with two 120 volt breakers. Now you really have two complete and independent circuits.
 
  #3  
Old 01-11-06, 07:46 AM
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I have a split panel, and thought only double beakers could be installed in the top section. The top section has 4 slots for double breakers for; range, dryer, 50 amp breaker for lower section of breakers, and an open slot. If two single 20 amp breakers will fit, that is what I will do. Thanks.
 
  #4  
Old 01-11-06, 02:31 PM
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You left out a very big point in your first post. Don't put anything in the upper half.

If you anticipate new electrical needs, I suggest you have the panel replaced.
 
  #5  
Old 01-12-06, 06:19 AM
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Don't put anything in the upper half.
Even if i am not adding any loads? Only breaking up current circuits. Like putting microwave on own 20 amp circuit.
 
  #6  
Old 01-12-06, 06:38 AM
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Don't put anything in the upper half of your panel.
 
  #7  
Old 01-12-06, 06:55 AM
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OK, Why?

Let me guess first, the upper half is not protected by a "main" breaker and there fore, not safe for a DYI'er. If this is the case then I am willing to hire an electrician to do it.
 
  #8  
Old 01-12-06, 11:14 AM
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All the breakers in the upper half collectively act as your main disconnect. The main disconnect protects the wires feeding your panel. Adding another breaker to the upper half of a split bus panel is equivalent to increasing the amp rating of your main breaker. Unless you first have someone verify that the wires feeding your panel can handle more amperage, it's not safe to add to the load to them.
 
  #9  
Old 01-12-06, 12:09 PM
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You might violate the "six throws" requirement if you put two single pole breakers in there.

I'd get an electrician to evaluate the capabilities of the service, and if it is adequate, install a sub panel.
 
  #10  
Old 01-13-06, 04:54 AM
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First, I want to correct what I said above, I have a split bus panel, not a split panel. Are these two different things? Has this been causing my confussion?

Second, I will add some background.

The panel is a by Frank Adam.

The upper section had four 2-pole breakers, two 30 amps for buit in oven and a counter top cook top. A 40 amp for the dryer. And, a 50 amp that feeds the lower section of 15 and 20 amp breaker. The Oven died and we went with an all in one range that required a 50 amp breaker. So I dissconnected to two 30 amp breakers. Removed one of them and replaced with a 50 amp breaker, and ran new cable from it to 4 prong range outlet. The other 30 amp breaker is still in place but turned off (and labeled to keep off). I want to remove this 30 amp breaker and replace with two single pole 20 amp breakers. Is this OK? Or does the Don't put anything in the upper half of your panel still apply?

If so, what are the thoughts of replaceing four or five 20 amp breakers with twin 20 amp breakers?

Third, I will hire an electrican to make all changes in the panel box.
 
  #11  
Old 01-13-06, 06:13 AM
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I am pretty sure that everyone understood that you meant 'split bus' panel.

As John Nelson pointed out, the set of breakers on the top half of the panel _together_ comprise your main breaker. These are what limit the current flow through your service entrance conductors.

You have already made changes which increase the 'size' of this main breaker, which means that your service entrance conductors could potentially be overloaded.

However when you increased one breaker from 30A to 50A, you took the other 30A breaker out of service, which sort of balances things out.

Now you want to put additional load into service.

This is something that could in theory be done, but is likely not allowed in practise.

Several things need to be evaluated:

1) The condition and amp rating of the service entrance conductors.

2) The total calculated load for your home.

3) The calculated load for the new circuits that you want to add.

If the total calculated load is less than what the service entrance conductors can safely carry, and if the new 'main' rating is less than the service conductors rating, then you could add the new breakers.

Adding skinny breakers on the lower bus is probably safer, but you may start seeing the 50A breaker tripping. Adding load to the upper bus is potentially okay, but you run the risk of overloading the service entrance wires, which is a big danger. In either case you are adding new load to the panel, so you should really calculate the load and make sure that you are not overloading the bus breaker or the service.

Given the age normally associated with 'split bus' panels, I suspect that what you are really looking at is replacing the entire service entrance.

Search this forum for 'demand calculations' for discussions about how to figure your home's electrical load.

I suggest the book 'Your Old Wiring' by Shapiro for a discussion of how to evaluate the condition of old electrical wiring and systems.

I suggest reading the book, and then posting back here discussing the details of what you find and evaluate. I suggest that you read this book even if you end up hiring an electrician, so that you know what questions to ask them.

Best Regards,
Jon
 
  #12  
Old 01-13-06, 01:23 PM
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Thanks Jon (Winnie). Based on your's and other's suggestion to upgrade, that is what I am going to do. The answers to your 3 questions are:
1) The condition and amp rating of the service entrance conductors.
43ish years old and worn at the metal clamps. It has printed on it something like "Narragansett 2-2-4 AL Type SE style ??? 5C" any ideas what that means?

2) The total calculated load for your home
is 25050

3) The calculated load for the new circuits that you want to add.
Is zero, just breaking current circiuts up. Putting Microwave on own circuit...

I am thinking of going to 150 amp service to be sure I have enough amps.
 
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