View Full Version : Single pole to double pole 240V
rjw76
Apr 4, 2008, 06:59 PM
Hello,
Hope someone can clarify/re-assure me of this. I currently have a baseboard heater in my bath and am converting it to in floor heating. The current setup is using a single pole thermostat (only breaking one of the legs) thus 120V always exists at the heater. Here is what I would like to do. Since I have removed the heater, can I not simply tie the two wires together at the heater to create two lines at my gang box? I may be over thinking this, but my black wire in the gang box is hot as is the red wire at my heater, so if I tie the red to the black at the heater I will have my two hots in my gang box... right?
One more question, the breaker is feeding three separate baseboard heaters with 3 separate thermostats, by implementing the above,will I affect the remaining two? Niether have more than 2 wires at either end, so I am assuming I must have a hidden junction box somewhere?
stanfortyman
Apr 4, 2008, 07:16 PM
Asking if you can tie the red to the black and such is pretty useless to us. We cannot see the wires and do not know what wires are where.
Start by telling us what wires are at what locations. We will go from there.
rjw76
Apr 4, 2008, 08:44 PM
Sorry.. I thought I was pretty specific. I have taken out the heater and thermostat, And have a pair of black and red wires at each (plus a ground). When the breaker is on, The black in the gang box is at 120V and red is 0V and at the heater, the red is 120V while the black is 0V. What I would like to do is tie the red and black at the heater together, thus completing the circuit and producing a hot red wire in the gang box as well... does that make sense?
stanfortyman
Apr 5, 2008, 05:53 AM
NO, it makes no sense. Does your feed comes into the wall box?
You say you ONLY have one black and one red in EACH location?? Are there any other splices in the wall box? Something is NOT right here.
You have a SP t-stat so the red is just spliced through down to the heater. That is why the red is hot. At the same time, the t-stat is breaker in the black leg which is why it is hot in the box and dead at the heater. If you tie red and black together you will inevitably cause a dead short.
What is it you need?? Do you need 120v for something or 240v?
Are you in Canada?
Stratmando
Apr 5, 2008, 07:29 AM
Are you wanting to tie 1 hot leg to heater and have the thermostat control the other leg to complete the circuit?
rjw76
Apr 5, 2008, 10:10 AM
I have one black and one red wire at each location. In the box, the black is hot and at the heater, thered is hot. What I want is to have two hot legs at the gang box, so I can install a double pole thermostat in it. I will no longer be using the baseboard heater, nor the wires that are currently there. That is why I want to tie the hot red at the heater to the black at the heater, thus producing two hot legs in the gang box. Make sense so far? From the gang box, I will feed a new 12/2 cable going straight down to the floor where it will feed the new in floor heating.
Hope that helps... yes, I am in canada
stanfortyman
Apr 5, 2008, 10:26 AM
A-HA! OK, the first thing you need to do is find the junction box where the splices are. There HAS to be another box somewhere, there is no other way you would have only one black and one red at each location.
Without finding this box it is quite unsafe to just tie the black and red together. You have no idea what else this circuit is doing.
Find that box, or the splices, and tell us what you have there.
I asked about Canada because up there you have "240v only" electric heat NM cable with only black and red. We do not have that cable here in the US.
rjw76
Apr 5, 2008, 03:11 PM
Thatiswhat I assumed... I mentioned that below:
One more question, the breaker is feeding three separate baseboard heaters with 3 separate thermostats, by implementing the above,will I affect the remaining two? Niether have more than 2 wires at either end, so I am assuming I must have a hidden junction box somewhere?
My problem is, the entire area is finished and I don't want to be fishing around for a junction box. Knowing that the breaker is feeding 2 additional heaters, is my suggestion still seem danagerous? If so, why? I can't wrap my head around it.
Thanks.
stanfortyman
Apr 5, 2008, 03:19 PM
my problem is, the entire area is finished and I don't want to be fishing around for a junction box. knowing that the breaker is feeding 2 additional heaters, is my suggestion still seem danagerous? if so, why? I can't wrap my head around it.Especially so. You have NO idea what wires go where. By tying the black and red together you will likely create a 240v dead short.
Try to look in other thermostat boxes for the offending splices.
rjw76
Apr 5, 2008, 05:31 PM
All the other t-stat boxes and heaters have the same configuration, only one pair of wires at either end. The only thing I can assume is that there is a junction box that branches out to every heater, right?
stanfortyman
Apr 5, 2008, 07:05 PM
Good assumption I'd say.
I would not assume however that the boxes are physically buried/hidden.
rjw76
Apr 6, 2008, 06:46 PM
Especially so. You have NO idea what wires go where. By tying the black and red together you will likely create a 240v dead short.
Try to look in other thermostat boxes for the offending splices.
I'm still trying to wrap my head around your comment about the dead short, the single pole thermostat is just acting like a switch for the black wire (lets call it L1) in the gang box, preventing the completion of the circuit att he heater. The red wire at the heater (lets call it L2) is hot. So if I tie the red at the heater with the black at the heater, aren't I really doing the same thing? In this case, it is acting like a permanent switch though. As a result, I will have L1 and L2 at the gang box where I can install my 2 pole thermostat. Am I over simplifying this now?