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Outbacker 06-02-2006 09:05 AM

Ganged circuit breakers
In my electrical panel, there are 2-15 amp breakers that have been ganged together and they were for used for supplying power to a large baseboard heater. I have removed the heater and will not be replacing it. I would rather run the wiring out to my shop for more power. Anyway, do the ganged 15 amp's equal 30 amps? If I run the power out to the shop, will I have theoretically 30 amps to the plug? It seems logical to me, but I would rather ask. Thanks.

Square Eye 06-02-2006 10:43 AM


The tandem breakers = 15 amps @ 120 volts x 2 breakers = 15 amps @240 volts.

Tandem breakers draw power from each leg of the 240 volt power source. Each leg is 120 volts. The breaker on each leg is 15 amps.

Outbacker 06-02-2006 01:54 PM

Thanks. What is the advantage of having ganged breakers? I know this seems like a silly question, but if I am still getting 15 amps, what does the 240 volts provide? Thanks again.

Square Eye 06-02-2006 02:23 PM

Amps x volts = watts

Flow x pressure = power

120 volts is plenty good for most household devices and accessories. To run a heating element large enough to heat a home or an A/C compressor, 240 volts handles the power much more efficiently. More voltage and less amperage runs cooler. More amperage generates more heat which is energy being dissapated into the air. A 120 volt motor running at the required amperage to match a 240 volt motor's output power, runs much less efficiently, is much larger, and will run much hotter and will not last as long as the 240 volt motor.

A tandem breaker, when overloaded, kicks both sides of the 240 volt hot wires. Each leg is 120 volts, if only one side had a problem in it's circuit, the tandem breaker will kick and shut power down to both sides. This protects the equipment from running underpowered or from damaging anything around it.

The powerlines out on your street are commonly 14,400 or 7,200 volts before it's reduced in the transformer in front of your home. Higher voltage is easier to deal with than higher amperage. If the power companies had to produce 120 volt at the required amperage, the wire would be as big around as you are tall. I think of voltage as pressure, amperage as flow, and watts are the resulting power.

inspectorD 06-02-2006 02:39 PM

I could not have explained that better.. that is exactly how I tell my students how it works.
I liken it to plumbing which everyone understands.
Nice job Square Eye...ever teach?:D

Gord Kurtenbach 06-14-2006 09:00 AM

related question
Hi. I'm renovating my kitchen and just moving the receptacles a bit. I found this thread and thought it might answer as question I have.

In our breaker box there are 2 15 amp breakers that are ganged together so they act as one switch. These are wired to single 14/3 cable with the black carrying the hot from one of the breakers and the red carrying the hot from the other breaker. The neutral is just the one white wire. This is then wired to 2 receptacles so that each receptacle is has its own breaker but share the neutral.

Seems this is just way of avoiding having to run two cables.

My question is: Is this a safe/accepted practice?


petey_racer 06-14-2006 06:34 PM

From what I know this is a very typical way of wiring kitchen receptacles in Canada.

Square Eye 06-14-2006 09:35 PM

Code in the USA requires 12-2 w/g and 20 amp breakers.

Tandem breakers and shared neuterals are acceptable to some inspectors, not to others. I have no idea what Canada electrical code is. Check your local electrical supply house. The guys who work in these places often have experience and can help with this sort of question.

petey_racer 06-15-2006 04:13 AM


Originally Posted by Square Eye
Code in the USA requires 12-2 w/g and 20 amp breakers.

Tandem breakers and shared neuterals are acceptable to some inspectors, not to others.

In the US, under the NEC, tandem breakers (in a panel that accepts them legally) and multi-wire circuits (shared neutrals) ARE legal.

Also, the NEC does not "require" 12/2. It simply requires 20 amp circuits for kitchen receptacles. If I want to run 12/3 an split wire the receptacles Canada style that is my choice, but it is still quite legal.

Square Eye 06-15-2006 06:07 PM

You wouldn't get away with it in Russelville, Ky. Mr. Whitehead didn't like it so it wasn't allowed.

The code is subject to the interpretation of the inspector.

I said 12-2, sorry, yes you'd have to run 12-3 to share a neutral.

What is your problem with me Petey?

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