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I'm doing a service panel change on my home and I always take a picture of the panel before just to use as a reference in case something in my labeling isn't making sense. So this is the before picture and it appears to show two 30a double pole breakers back to back in the middle of the panel. I added white circles around the wires so you can see what I'm talking about but it would appear that there are 3 240v circuits being ran off of just the 2 double pole breakers. It's done in a bit of a weird way but I kind of see how it made sense when whoever did it. I know square d's are made to accept 2 wires but I was not sure that this is ok to do considering the draw of the 3 different appliances these wires are used for. I have not traced those wires out so I can't say for sure what they feed. Is this an acceptable wiring to duplicate after I do the panel change or should I just add an additional 30a double pole to connect up that 3rd branch circuit?

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    Maybe it's just a bad photo, but the black and white wires going into breaker 7, look to be too small for a 30 ampere circuit. – Tester101 Aug 9 '17 at 10:45
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    What do those 240V circuits feed? – ThreePhaseEel Aug 9 '17 at 11:42
  • I am pretty sure Square D's panel labeling allows two wires per breaker binding screw, one on each side of the screw. Three wires on breaker 7 and 19? Now that looks real suspicious. – ArchonOSX Aug 9 '17 at 15:57
  • Do you have electric baseboard heaters? – Tester101 Aug 9 '17 at 16:07
  • Yea I definitely just need to trace out the couple circuits in in question here. The service change is done and all the work passed inspection today. Only thing I wasn't aware of was those weird new grounding bridges that need to be install somewhere beside the panel. I'll keep you guys posted. I do believe it is just deceiving in the picture the size of the wires involved. I'm not looking at it right now but I think it's all 10 wire used. – Joey santos Aug 10 '17 at 4:56

I can't think of any way this could be code compliant wiring, but it might make more sense if we knew what the circuits were supplying.

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    When you install the new panel, try to keep the wiring a bit more tidy. – Tester101 Aug 9 '17 at 10:48

No problem

In house wiring with flexible cables (NM/Romex), it is common practice to run circuits serially - going from one outlet to the next, etc. However, there is nothing wrong with wiring a circuit in a "Tee" configuration - branching in two or more different directions.

There is also nothing wrong with the "Tee" starting right at the breaker. This is why some breakers allow two wires, to spare you a splice in the panel (which is also allowed). It should be noted that this is one circuit. It just happens to tee at the breaker.

The most obvious application for a "Tee" at a breaker is electric heat. For instance a 30A breaker can support four 1500W heaters in various parts of the house.

The rules, though

**Every* wire in the entire circuit must match the breaker rating.

Why? In any circuit, you have no idea where a short will be. Worst case is a limited short which draws somewhat more current than the circuit rating. It's now a "race" to see which overheats first: the wire or the circuit breaker. For safety, that must be the circuit breaker.

So if the breaker is 30A, every wire in the circuit must be 10AWG. (we're presuming a circuit which branches, so the odd exceptions for certain single loads do not apply.)

That funny business over on breaker 7, with the conspicuously thin wire, looks super wrong. That is an example of the amateur, horked-up, no good hackery that happens when you don't have readily-available spare spaces in your panel. This is why it's so important to get a Really, Really Large Panel.

I see where you're ripping out a 30-space Homeline panel, it's not obsolete and GFCIs are cheap for it. So I'm guessing either you need a bigger main, you prefer quality, or you're out of space. (double-stuff breakers are also plentiful and cheap for this panel, but that's ugly business.)

Since you're at 28, I'd aim for somewhat more than 40. Homeline doesn't go any bigger than 40. Others do but price is steep. You can also use subpanels to increase your available spaces, and you can do that later.

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    If the installer was simply feeding two baseboard heaters from each breaker, why would there be only 3 wires on each breaker and not 4? Or do you think the installer is feeding 3 120V heaters with a shared neutral? – Tester101 Aug 9 '17 at 16:05
  • I'm pretty sure that SquareD has a 60 circuit HOM panel these days...(it's one of the plug-on neutral boxes tho) – ThreePhaseEel Aug 9 '17 at 22:22

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