Recently I have some across several baseboard electric heaters that were wired together. Usually they use the thermostat controlers that were designed to run only one heater or at the most two heaters. The real solution is to use contactors. These are heavy duty relays designed to hadle 30 amps or more. You can have dual or tripple 30 amp breakers going to the contactor then have the heaters wired in groups of two, or three with 10 gauge wire, connected to the contactors. This is a example of a system for running four baseboard heaters.
My brother contacted me about his heating sytem dying. I discovered the the coil of the top contactor was shorted and the 24 volt transformer was fried. So I disiconnected it and he could just use the bottom contactor to power half of his heaters temporarily. However the bottom one quickly died. The coil on the bottom contactor had shorted as well. It turns out thse contactors have a problem. The coil gets so hot that it partly melts the coil form and then it shorts out. The picture is of a three phase system, the three phases on the left and the heaters are on the right.
Another issue is that there is no schematic diagram of how to wire multiple heaters up. Here is a simplified wiring diagram for up to six heaters. Another contactor can be added for up to12 baseboard heaters. On a three phase system you can use a tripple 30A breaker but then you need 20 amp breakers or fuses if you have smaller 12 gague wire going out to the heaters. That setup saves room in your breaker box.
