Before buying a set of HomePlug powerline ethernet adapters, I'd like to know if the 120 V sockets I plan to use are on the same phase or not. Is there any easy (and inexpensive) way to figure that out? Those adapters don't really work across different phases. I live in the US.
Find which circuits they're on. If they are on the same side of the breaker box and there is an odd number of breakers between them (not the numbers, but the spaces) they will likely be on the same leg. If they're on the opposite side, count evens. This isn't 100% assured, but it should work. A peek inside will tell you for sure.
Find out what breaker the receptacles are on and then look at where those are plugged in. They're interleaved with every other breaker down the row being on the same bus. If they're on opposite sides you can usually swap two side by side breakers to get the one you're interested in on the side you want it.
The X-10 folks sell a bridge you can put across the phases that will pass the high frequency PLC signals across to the other phase. It is basically just a capacitor but it is in a U/L listed package.
pull a fuse or switch a breaker and test each outlet, you will then know which ones are on the same circuit.
That doesn't tell you which side of the center tap they're on. The two "hots" are interleaved down each side of the panel, so an odd number between will be on the same "side" of the transformer.
Not if the breakers go to a 3-wire. The black and red of a 3-wire have to remain on opposite phases or you risk burning up the neutral and starting an electrical fire.
Sigh. If you connect the red & black to the same phase for a 240 volt load, it gets zero volts.
I already know they are NOT on the same fused circuit. I just don't know if they are still on the same phase or not.
Like the original poster, I was talking about 120 volt circuits and then expanded upon your answer to clarify when a 3-wire is is used as the homerun to the panel. A 240 volt load has nothing to do with it. With a 3-wire homerun, the black and red have to be on opposite phases in order to have the neutral carry the unbalanced load. If the breakers for the black and red were on the same phase, then the neutral could end up carrying the full load of both circuits and burn up. So because of potential 3-wire homeruns, one cannot simply swap breakers that are next to each other without knowing if it can be safely done.
Well when you know what fuse/breaker each is on, then you know which phase each is on just by looking at the panel.
I hadn't thought of those, I've seen it done once, but I don't particularly care for the idea. Personally I always use standard 2 conductor cable so each 120V circuit gets its own neutral.
Multiple circuits are usually on the same phase. What you want to do is get a circuit tester and string it from the hot line of one to the hot line of the other. If there's enough differential voltage to light the tester, they're on different phases. If there's not, they're on the same phase, but perhaps not the same circuit.
Or you could use a voltmeter. The voltage between different phases in a house is 240 volts or so. The voltage between different outlets on the same phase is a lot less than 120V. In a building with 3-phase power, you will see either about 240 or 208 between phases. Again, if it's a lot less, it's the same phase.
OK, I made a couple of pics of the breaker panel and I hope you can view them on the following links.
These are the breakers:
The circuit breakers I am interested in are the blue ones on the left and the one immediately above them, labelled "Foyer, etc." For some reason it's 30A, while the blue ones below are 15A. I'd like to be sure that the "Foyer" breaker is on the same phase as the 2nd from the bottom, labelled "Kitch/Fam Rm Lights." I'd rather not call en expensive electrician to install a bridge capacitor or whatever.
The following link shows some info about the breaker panel and it's pasted inside of the panel door:
I hope it can help you experts to answer my original question so I don't end up with a useless HomePlug kit.
They are not on the same phases. The "Foyer" breaker is on the "A" phase while the "Kitch/Fam Rm Lights" breaker is on the "B" phase. What might be confusing you is those blue breakers are mini breakers. They are nothing more than two 1/2" tall breakers bound together to fit into one 1" tall breaker slot. Each 1" tall breaker slot is on a phase. The first left/right pair starting at the top is on the "A" side, the second left/right pair is on the "B" side, the third left/right pair is on the "A" side, the forth left/right pair is on the "B" side, etc.
Um sorry I make a mistake in identifying the "A" and "B" phases. Everything I wrote is correct except that you'll need to swap every "A" with a "B" and vice-versa.
Oh, shoot! There goes my HomePlug idea unless I really want to call an electrician. But that in itself would probably cost more than a good HomePlug kit. Anyway, thanks for the reply.
The legs/phases/buses in the panel are interleaved, so the first slot is leg A, the next one down is leg B, the one below that is leg A, and below that B, and so on. The blue breakers are doubles, so each pair of those is a slot. In your case the garage light is on the same phase as the kitchen lights
It just occured to me that X-10 and HomePlug frequencies are quite different and I wonder if that X-10 bridge would even work for HomePlug.
Does not matter he just wants the adapter on the same bit of wireing.
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