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Trying to use Powerline data/control devices and need to figure out which phases in my house go to where.

The double breakers are confusing me further - and I know they alternate phases vertically but is it the same phase right to left?

Question: Are the two breakers with red arrows on the same phase?

(120v+120v=240v)

Breaker panel

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  • Your panel is fastidiously well-colored, with all the reds on the same phase, and only 4 blacks which "should" be red. It's legal to mark them as such with electrical tape. You seriously need a bigger service panel, though. All those blue-handle breakers are "double-stuff" breakers with 2 breakers in one space, which makes it impractical to go AFCI or GFCI. Jan 25 '17 at 2:26
  • I know I love how clean it is, townhouse from 90's - developer must've been cutting corners.. Trying to use powerline ethernet on those two, and getting very poor signal. Must be something else// *Or perhaps something to do with the double breakers? Jan 25 '17 at 3:57
  • Also - wondering why the upper right ones are linked together in pairs? They go to the kitchen outlets so I don't see why they're linked unless it's code to do so? Jan 25 '17 at 4:02
  • Probably because they are multi-wire branch circuits. Those don't require common overcurrent trip... But they do require common maintenance shut-off. I am glad your installer had good color discipline, because it is Very Important each side go on a separate pole. Jan 25 '17 at 4:56
  • Terminology question: Why are two circuits on different legs which use the same neutral conductor called "multiwire branch circuits" and not "shared neutral branch circuits"? Jan 25 '17 at 18:38
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Yes, they appear to be on the same leg.

enter image description here

Unless there's something I'm missing.

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  • No appears that is the correct way, thanks for labeling them! Jan 25 '17 at 3:53
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    Q1 It is always true for US panels that the two breakers exactly opposite are on the same leg, right? Q2 If one wants to determine whether two receptacles are on the same leg or on a different leg, one measures the voltage difference between the two hots? Zero volts same leg, 240 V different legs. This will in general require an extension cord plugged into one of the receptacles. Jan 25 '17 at 8:09
  • @JimStewart diy.stackexchange.com/a/13107/47336
    – TFK
    Jan 25 '17 at 12:12
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    Wow, I used to provide really good answers.
    – Tester101
    Jan 25 '17 at 12:22
  • The breakers for 120 V branch circuits for my 45-year-old GE panel are individual 1/2" wide breakers. I mistakenly thought that as one moves down in each column of breakers the legs changed on each breaker, but it actually changes every inch. GE has a mechanical arrangement for preventing a 2-pole (2 x 1/2") breaker from being connected to pins on the same leg. I did not perceive this and tried to force it in. However, I did stop before I damaged the breaker or the panel or hurt myself. A trip to an electrical supply didn't enlighten me. A Google search did. Jan 25 '17 at 13:52

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