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What does this breaker mean?
- Thread starter kengchang
- Start date
Common trip breaker. Both of the 15A poles marked "Second Floor Power" trip together. For some reason it needs 15A of 240V power on the second floor. The Water heater, kitchen lights and family room lights also trip together. Since you have empty spaces, I think someone cut some corners where separate 120V and 240V breakers could have been used.
If you number the outputs that switch controls as: 0, 1, 2, 3 (left to right or bottom to top), then
* 0 & 1 are phase 'B', each 15A
* 2 & 3 are phase 'A', each 15A
* 1 & 2 are paired so that they both turn-off/trip at the same time
* 0 & 3 are paired so they both turn-off/trip at the same time
* 2nd-story power gets two lines of power, Phase A & B, via switch output 0 & 3, for a total of 30A
* 1 & 2 is are split as 120V outputs, 15A each and you have loads as labeled using them.
* 0 & 1 are phase 'B', each 15A
* 2 & 3 are phase 'A', each 15A
* 1 & 2 are paired so that they both turn-off/trip at the same time
* 0 & 3 are paired so they both turn-off/trip at the same time
* 2nd-story power gets two lines of power, Phase A & B, via switch output 0 & 3, for a total of 30A
* 1 & 2 is are split as 120V outputs, 15A each and you have loads as labeled using them.
Hmmm I am not aware my 2nd floor has any plug that runs 240V. So I should buy another 120V breaker to separate it?
Really, you should talk to the person who installed it and ask why they did it this way. If that's not possible, turn each pair off and see what doesn't work any more.
woferry
Member
Most likely, to save wiring effort (and/or cost), some runs were done using /3 romex (i.e. 12/3 or 14/3) instead of /2, meaning there are 2 hots and one neutral (3 conductors, plus ground ideally), and the two circuits share a neutral (the 'second floor power' might go to a separate sub-panel also, I guess, but with 15A breakers that seems unlikely to me). Using /3 wiring is OK when the two circuits are on opposite phases as the neutral won't see the sum of the currents (in fact if the two phases drew the exact same amount of current the neutral wouldn't carry any current at all). But you need to ensure that if one of the hots is de-energized (either because the breaker tripped or someone switched it off to work on the circuit) the other one turns off as well, or else someone might think it's OK to work on the circuit because the hot line is off, and the neutral line may still be carrying current. In those quad-style breakers, the top two switches are on one phase and the lower two on the other, so the linked circuits can either share the middle two switches (linked via the rod) or the outer two linked using that metal plate.
In my 1960-built house one circuit pair used 12/3, as the two circuits were each single-outlet located right next to each other (kitchen and garage which share a wall, far from the breaker panel). Everything else was separate 12/2 runs, except for the higher-current appliances like the dryer and range. Though when Tesla re-wired everything into the new backup load panel they mis-identified which circuits shared the neutral and linked the wrong ones, I wound up having them correct it as the city inspector had everything open for inspection and I realized it was done wrong.
In my 1960-built house one circuit pair used 12/3, as the two circuits were each single-outlet located right next to each other (kitchen and garage which share a wall, far from the breaker panel). Everything else was separate 12/2 runs, except for the higher-current appliances like the dryer and range. Though when Tesla re-wired everything into the new backup load panel they mis-identified which circuits shared the neutral and linked the wrong ones, I wound up having them correct it as the city inspector had everything open for inspection and I realized it was done wrong.
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