breaker amp rating question

2439 Views 4 Replies 4 Participants Last post by nap, Jul 19, 2009

Red Squirrel

Discussion Starter · Jul 19, 2009

Say I need to run a 240 volt circuit that needs 15 amps, would I get a 15 amp double breaker, or would I need a 30 amp? Does the rating assume the amperage to be at 120 volts? As 15 amps at 120 is less power then 15 amps at 240. Also, is it against code to have all the breakers add up to a bigger number then the main breaker? I only have 100 amp service and if I go and add another high amperage breaker I will probably surpass it, if it's not already surpassed. Technically it's safe as if I happen to use all that power at once, the main will do it's job and trip. And one last question, are breakers fairly standard or do I need to get the same brand? My panel is fairly old, it's a Stab-Lok.

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jbberns

· #2 · Jul 19, 2009

1. 15 amp double pole.
2 It's ok to have breakers that add up to more than your main. I'd say most panels do. I wouldn't worry about it unless your main starts tripping a lot.
3 Use the same brand breaker as the panel.

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Scuba_Dave

· #3 · Jul 19, 2009

Yup, breaker size is breaker size - the device being wired should specify 120 or 240v

I have over 800a of breakers in my house between main panel/subs & a 200a Main breaker

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Red Squirrel

Discussion Starter · #4 · Jul 19, 2009

That's good to know. Thanks.

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nap

· #5 · Jul 19, 2009

Red Squirrel said:
My panel is fairly old, it's a Stab-Lok.

replace the panel.

if you want reasons, google stab lok. You will get more than enough info to scare the dickens out of you.

On top of that, buying a stab lock 2 pole breaker will be about 1/3 the cost of a new panel (not including installation). At least it was the last time I had to hunt one down.

but a 2 pole 15 amp breaker allows 15 amps of current. A 2 pole 30 is good for 30 amps.

and as long as the main is not tripping (except in the case of a FP stab lok panel) it means the panel is adequately large enough to supply whatever you are powering. As Dave said, adding up the breakers often to more than the main breaker. Not a problem.

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