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#1
01-07-05, 06:52 AM
Member
Join Date: Jan 2005
Posts: 15

I am a new homeowner and would like to add a couple outlets to the unfinished basement of my 6 month old house. I understand all the wiring details but am a little confused regarding the breaker panel. I guess I just assumed that the total amperage of the breakers installed must be less than the amperage of the main. This cannot be true however since there are much more than 100 amps worth of breakers installed on my 100 amp panel. How do you determine how many breakers(amps) can be run off a given panel? I already have 4 15 amp breakers that are labelled "spare". Does this mean that I can safely add 4 more circuits? How about more breakers? Thanks in advance!!

#2
01-07-05, 07:12 AM
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Join Date: Sep 2000
Location: United States
Posts: 18,497
The sum of the breakers is meaningless. Sometimes they add up to four times or more the main breaker. And you cannot assume that you can add more just because there is space for them. The real answer is complicated, and is called a "demand load calculation". If you google that term, you'll learn more--but you may not want to.

Adding breakers and a couple of outlets does not add any load at all until you plug something in. The extra load is entirely dependent on what it is that you plug in.

We can give you a gut feel if you tell us the square footage of your house, whether your major systems (home heat, cooking, water heat, clothes drying) are electric, and how much if any air conditioning you have.

#3
01-07-05, 08:45 AM
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Join Date: Jan 2005
Posts: 15
Electric washer, dryer, stove, central A/C, and about 1800 square feet of finished living space. Furnace and water heater are gas. I really only need the 2 additional outlets on one circuit for power tools at my workbench but was just curious about the rest. Thanks again!

#4
01-08-05, 11:54 AM
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Join Date: Sep 2000
Location: United States
Posts: 18,497
Two more outlets for power tools creates no significant extra load. Go for it.

#5
01-08-05, 12:01 PM
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Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
If you have breakers marked as spare, and if there is really nothing already on those breakers, then you can connect your new circuit to one of them. However, I would seriously consider buying a new 20 amp breaker and using it in place of one of those 15 amp breakers.

A 20 amp circuit is more versatile than a 15 amp circuit. At the very least I would use 12 gauge wire for the new circuit(s) with the 15 amp breakers, so that you could swap the breaker out at a later date, if necessary.

#6
01-08-05, 02:23 PM
Member
Join Date: Jan 2005
Posts: 15
Originally Posted by racraft
If you have breakers marked as spare, and if there is really nothing already on those breakers, then you can connect your new circuit to one of them. However, I would seriously consider buying a new 20 amp breaker and using it in place of one of those 15 amp breakers.

A 20 amp circuit is more versatile than a 15 amp circuit. At the very least I would use 12 gauge wire for the new circuit(s) with the 15 amp breakers, so that you could swap the breaker out at a later date, if necessary.

Well, Its already run in with 14 so I guess I'm stuck with the 15 amp anyways. Thanks for the advice!!

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