Curious about my wiring here in my old apt. I'm in the US with 240V on two phases for my baseboard heating here, at least I think. I tore off the thermostat from the wall to do a wiring check to consider throwing a Shelly in there to monitor energy usage and what I found I really didn't expect. I figured I would find a single live and neutral for both the source and the load. But, there seems to be 2 phases available with a neutral between them. I'm not sure how the wiring is supposed to be, or if this is just normal here. Pic is of the measurements I took with my meter. My question is, what gives? there is 120V between the two "neutrals" wired to the thermostat. The shelly wiring guide says to throw those two together. I am obviously not doing that. p.s. the white cap in the back is a couple of bare wires tapped together, assuming ground. This is an old apartment that my landlord's old husband has been maintaining by himself for a while. There are two rooms with baseboard heaters wired into this panel. I assume they are wired in series, cause there simply aren't enough wires to account for both of them.
>>2885947It is a 4-wire line voltage thermostat. One side, either black or red should have both legs of the 240v supply. They tend to be reversible, so no guarantee on which side is which. The other side should go to the load(heater). One of the white wires is most likely the other 120v leg, it should have a piece of black or red tape to mark it but electricians are lazy. There is typically no neutral used in a 240v base board system.
>in the US with 240V on two phasesIt's still just one phase.
>>2886107What you described is not how my wall thermostat is wired. There is a black and white hot, with 240v between them but they are attached to a black and red wire at the top of the thermostat, see OP image. The thing is, each of those hots have 120v to each of the remaining two legs (guessing the load). Nothing is labelled. The image you posted is of a baseboard-mounted thermostat, mine is a Honeywell wall mounted one. I just wanna understand what is supposed to go where at this point! I figure this setup can't be too uncommon, it's the US after all
>>2886554If there's 240v between the two then it doesn't need a neutral. The power flow betweens the 240v without going to a neutral.It's like one of the 120s you measured is + and one is - and together they're 240
I know the thermostat and loads don't need a neutral. Shelly calls for a neutral, but I'm assuming that's fine. My problem is that I have disconnected everything and turned the breaker on, and I still see 120V across either live wire and either leg of the heater wires. This is with everything disconnected... Won't I cause a massive short by bringing the "neutral" from the heater to the + or - 120V? If the heater truly was floating, I shouldn't see a potential between them and the live wires at all. If I really have both wires from the heater then they should be floating. What am I actually missing here?
>>2886581There is no neutral, you have two legs, both 120v to ground. In residential wiring, always remember, all neutrals are white but not all whites are neutral. Your heaters are also likely in parallel, not series as they would only run at half power in series assuming they are the same size. Check the actual heater connections to see the tie in point for the other heater, it may not be done at the thermostat.As for your thermostat wiring, they should be labeled on the case, but looks like top are source, bottom are load. Most likely case for your confusion is you have a ground fault in one of your heaters or their wiring, so you are measuring one leg to ground off each side.
