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What does 2/4 circuits mean?
I am researching how to install an electrical sub-panel in my garage. In looking around the hardware store's website, the number of breakers/circuits that the panel can physically hold is listed as 2/4, or 12/24, or 30/60 etc. I'm not sure what this means? I would like to be able to install 3 breakers total, 1 for interior lighting/outlets, 1 for exterior lighting/outlets, and 1 2-pole breaker for my radial arm saw that needs more juice.
I'm not getting into all the specific electrical details like wire sizing, breaker sizes etc. here, I have done that elsewhere and understand how that all works, and I don't want it to confuse anything else here. I just want to know if a panel is capable of handling 2/4 circuits, does that mean it physically has enough space to install 4 total breaker switches (say 2x20's and 1 x double 40). Google is not being very helpful with this one. Thanks for any help you can provide!
2 Answers
- Irv SLv 78 years agoFavorite Answer
The second number usually refers to 'piggyback breakers.
Two breakers in one slot. You usually don't want these.
In a garage you will need GFI breakers and they don't piggy-back.
You need 4 slots for your present requirements.
If your garage is a separate building, you need six,
(two for a required 2P. 'MAIN plus the 4 you plan').
It doesn't make sense to go to the trouble of installing a panel with no spare capacity,
so buy a 12/24. the box size increase costs little you needn't fill the slots till you
add the extra breakers.
Same goes for cable and mains- at least one size 'over'.
Remember to allow for a start surge for that saw motor.
Source(s): Retired Electrical Consultant - DavidLv 68 years ago
Circuit breakers come in 2 physical thicknesses, so 2 thick or 4 thin breakers fill the same (2) breaker "slots." This is so that breaker you forgot when you first installed the panel can be installed later, by taking out a thick breaker and inserting 2 thin ones in the slot!
BUT the thin ones do not work as "double" breakers, necessary for 220/240 volt circuits.
So, while the 4/8 size would handle your present needs, I would suggest you go to the next higher size available. Some day you might want to install air conditioning, what with global warming and all! It is SO much easier to install a breaker or two in the existing box than it is to replace box and all.
Source(s): Professional electrician for many years.
