Hello, I'm thinking of adding a receiver and TV speaker's to an existing line, but am having trouble understanding my breaker box switches.
I have square D 200 amp breaker box. On the first picture I've attached, left hand side at the top, you can see two slots with a single switch in each. Below that are smaller switches (i.e. two switches per slot). The larger and smaller switches are 15 amps each. Am I looking at this correctly, or are the slots that have two switches on them a TOTAL of 15 amps (i.e. 7.5amp each) vs. 15 amps each? Why are the 15 amp switches different sizes?

I've attached a second picture which shows the full box.
Thanks for the help,
Jk

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Originally Posted by jkennedy99

I have square D 200 amp breaker box. On the first picture I've attached, left hand side at the top, you can see two slots with a single switch in each. Below that are smaller switches (i.e. two switches per slot). The larger and smaller switches are 15 amps each. Am I looking at this correctly, or are the slots that have two switches on them a TOTAL of 15 amps (i.e. 7.5amp each) vs. 15 amps each? Why are the 15 amp switches different sizes?

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Yes, you are correct. The smaller breakers/switches have the same current rating as the larger switches. It is a "per switch" rating, not a "per slot" rating. My local inspector doesn't like the smaller ones, but they are UL approved and he says he can't tell the local electricians not to use them. Normally, I prefer to use full-sized breakers unless the box is full. Then, I'll use the smaller breakers (2 per slot), but only when absolutely necessary.

For all I know, there may be locations where the local inspectors will refuse to let you use them.

Thanks for the info.
One other question. When I add up all the individual breaker switches, the amp total is much higher than 200 amps, which is what the box is rated for. Why is that? Is it just assumed you would not have all the lights/ outlet/ dishwasher/ oven etc running at one time?

Quite correct. The box should be protected with a 200 amp main breaker. If the current drawn exceeds that, it will trip and shut off power to the whole house.

Each pole of those tandem breakers is 15 amps, not 7.5. The tandem ones are the ones with two handles in a single slot.

Quote:

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Originally Posted by jkennedy99

Thanks for the info.
One other question. When I add up all the individual breaker switches, the amp total is much higher than 200 amps, which is what the box is rated for. Why is that? Is it just assumed you would not have all the lights/ outlet/ dishwasher/ oven etc running at one time?

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You are correct. You do not turn everything on all at once.

Think of a tree, with a branch that can support 100 pounds. On this branch are 20 twigs that can support 15 pounds before breaking off. If you hang a 25 pound weight from the twig, it will break, but the limb will not be affected. However, if you load every twig with 10 pounds each, none of the twigs will break, but the branch which can only support 100 pounds so it will break.