Baseboard Heat Mystery

glaciallakes · 01-23-2009, 09:01 PM

I've searched on here for an answer for this problem but can't figured out so let's see if anyone might have a solution. I have one electric baseboard heater that will not work. Ive eliminated everything within the heater and it seems to be in the wiring in the house, but i dont understand what's going on. The heater is 240V and is on a 20A breaker with a total of 4 heaters cascaded and this one is the last one. When I test the voltage at the problem heater I get 115 V from white to ground, 115 V from black to ground and 0 V from white to black. On the heater that work on the same circuit I get 240ish V checking white to black. I also get 240V at the breaker. It seems like the polarity is messed up somewhere along the circuit but I checked the other thermostats, heaters, and connections, and all seems to be normal. I could be missing something. All the thermostats are single pole. Am I missing something obvious? Please help! Thanks in advance!

dSilanskas · 01-23-2009, 09:11 PM

You have other baseboards on this t stat in the room? And they all are working?

PaliBob · 01-23-2009, 09:25 PM

You may have an open. With pwr off make some comparative resistance measurements.

Stubbie · 01-23-2009, 09:34 PM

Quote:

The heater is 240V and is on a 20A breaker with a total of 4 heaters cascaded and this one is the last one. When I test the voltage at the problem heater I get 115 V from white to ground, 115 V from black to ground and 0 V from white to black

.

Could also be one of two things

Your testing shows that the problem heater is either miswired to the heater preceding it or it is not on the same circuit and has both the heater hots connected to the same leg.
0 volts between white and black at the heater that is not working is telling you that the black and white are on the same leg of the service. They need to be on opposite legs. Thats what the double pole breaker does. If that heater is indeed supplied from the heater preceding it then you have a miswire at the working heater. Your black and white both have been connected to either the black wire or the white wire at that heater. They need to be connected black to black and white to white not black and white to black or black and white to white.

joed · 01-23-2009, 09:37 PM

Disconnect the wires from the heater and measure the voltage again. I think you are going to find one of them is 0 to ground. One of the leads is open. The voltage to ground on the other lead is coming through the heater.
Check the other end of the cable feeding the heater. Probably a loose connection.

Stubbie · 01-23-2009, 09:51 PM

Quote:

Originally Posted by joed

Disconnect the wires from the heater and measure the voltage again. I think you are going to find one of them is 0 to ground. One of the leads is open. The voltage to ground on the other lead is coming through the heater.
Check the other end of the cable feeding the heater. Probably a loose connection.

I suspect that this is going to be the actual problem. I think that is what Palibob was suggesting.

glaciallakes · 02-02-2009, 05:22 PM

Thanks for the replies guys. I havent had time to work on this for a while and double checked the problems. I am very sure that there is a problem in the wiring preceding this heater. The measurements at the problem heater were measured without the heater or tstat hooked up. This heater is on its own tstat and it is right in the heater. the other heaters on the cricuit each have their own tstat. I know which heaters are on the circuit, but I am not sure what order they are in. What tools do I need to try to follow the wires back to find the probable miswiring? Some sort of tone generator. Please advise! Thanks

Steelhead · 02-02-2009, 11:05 PM

Quote:

Originally Posted by glaciallakes

Thanks for the replies guys. I havent had time to work on this for a while and double checked the problems. I am very sure that there is a problem in the wiring preceding this heater. The measurements at the problem heater were measured without the heater or tstat hooked up. This heater is on its own tstat and it is right in the heater. the other heaters on the cricuit each have their own tstat. I know which heaters are on the circuit, but I am not sure what order they are in. What tools do I need to try to follow the wires back to find the probable miswiring? Some sort of tone generator. Please advise! Thanks

This is what I would do:
Turn off power at the breaker. Disconnect the wires feeding each heater. Go to the heater that you suspect has the wires feeding the heater that doesn't work. Connect the black and white wires together - they will be in the same sheathing (I'm guessing this is NM cable?) Now go back to the heater that doesn't work. Using a multimeter or equivalent test for continuity by putting your test leads on the black and white wires. If there is continuity then you have found your wire (cable) if not follow the same procedure for the other cable in the heater where you tied the white and black together. Continue to follow this procedure on all the heaters until you find continuity.

Before you reapply power make sure all your connections are back to normal.

Normal should be: Incoming and outgoing cables should have the blacks tied together and the whites tied together.