Electrical question

[Joe Bourbois]

Awhile back, I had two 220v outlets installed in my garage shop. They are both directly below one of electrical panels. They are shown in the first picture below.

I wasn't there when the installation occurred so I wasn't able to ask the electrician any questions. My question relates to the breakers he put in for the two plugs. The outlet on the right is connected to the breakers occupying spaces 20 and 22 (you can see the silver bar that joins the breakers). The outlet on the left is connected to the breakers occupying spaces 17, 19, 21, 23.

Why the discrepancy between the two outlets? They are identical outlets and I know he used 12 ga wire to both.

Thanks for any advice or comments.

[Brian Bischoff]

Joe,

If I am looking at your photo correctly, you really have a 12 slot panel. In some panels you are allowed to use half size breakers as you have on the right side of your panel which potentially could allow you to have 24 circuits in a 12 slot panel. Many people (me included) do not like half-sized breakers unless absolutely necessary. Normally when numbering your slots you have 1,3,5,7,9,11 on the left and 2,4,6,8,10,12 on the right. When you use half-sized breakers you don't re-number them to 1-24. You have circuit 10A, 10B, 12A, etc. Actually what you have is a full size double pole breaker on circuits 9&11 for one outlet and a half-sized double pole breaker on circuits 10 and 12 (actually 10B and 12A) for the other. As you can see, the half-sized double pole breaker is positioned so that it has one leg on one phase (10B) and one leg on the other phase (12A). This should work fine.

Brian

[John Davidson]

Joe,

If I am looking at your photo correctly, you really have a 12 slot panel. In some panels you are allowed to use half size breakers as you have on the right side of your panel which potentially could allow you to have 24 circuits in a 12 slot panel. Many people (me included) do not like half-sized breakers unless absolutely necessary. Normally when numbering your slots you have 1,3,5,7,9,11 on the left and 2,4,6,8,10,12 on the right. When you use half-sized breakers you don't re-number them to 1-24. You have circuit 10A, 10B, 12A, etc. Actually what you have is a full size double pole breaker on circuits 9&11 for one outlet and a half-sized double pole breaker on circuits 10 and 12 (actually 10B and 12A) for the other. As you can see, the half-sized double pole breaker is positioned so that it has one leg on one phase (10B) and one leg on the other phase (12A). This should work fine.

Brian

I have been wiring for years and Brain has hit the nail on the head. I have never thought it was that big a savings to justify using smaller panels and half size breakers but many contrctors do it. I perfer the full size breakers but can not say that I have ever seen a problem from using the half size ones.

[Von Bickley]

Joe,
Brian explained it very well. The only thing different is the physical size of the breakers. I agree with Brian on preferring the full size breakers but sometimes you don't have the choice. Everything looks O.K.

Von B.
"Wantabe Woodworker" and certified electrician

[Joe Bourbois]

Thanks guys! You've explained it very well. I feel better now.

[Chris Padilla]

Why are you guys scared of half-sized breakers? They are fully approved and accepted by the code aren't they?

Just curious.

[Jim Becker]

Why are you guys scared of half-sized breakers? They are fully approved and accepted by the code aren't they?

Yes, they are fully approved, etc. But sometimes folks "over use" them and might actually over populate a breaker center based on amperage, etc. I used a bunch of them in the shop prior to getting the new service put in as it was the only way to get enough 240v circuits in the smaller box. Most cabinets are also rated for "both" types. Like anything...moderation is sometimes a good idea, but as long as you play by the rules you'll be fine.

[Rob Russell]

... But sometimes folks "over use" them and might actually over populate a breaker center based on amperage, etc.



Specifically,there is an NEC maximum of 42 "overcurrent devices", where an overcurrent device is defined as a pole on a breaker. Putting it differently, you can have a max of 42 hot legs supplied by one breaker panel, where a 240 volt circuit counts as 2 legs.