I am trying to resurrect an old baseboard system I pulled out 5 years ago to replace exterior walls...http://www.hearth.com/talk/threads/backup-heat.101152/ All of the heater loops were powered by 4 adjacent 20 amp single breakers. One of the cables went through a Honeywell box that the thermostat goes to and then to one end of the string of heaters. The second cable went directly to the other end of the string of heaters. A few ?s: 1. I would like to string 10 of the units together. They are 240V single phase 600 watt 2.5 amps. Do my 4 20 amp breakers effectively give me a 40 amp circuit? i.e. 25 amps is ok? 2. All of the cabling is 12 wire. Does this mean I can't string 10 units together safely? 3. It looks like half the strings of heaters are wired parrallel on the two white wires and the other half on the two black wires. Does this make sense? 4. Should both cables come out of the wall with 240 across the black and white when the tstat is calling for heat and only one when the tstat is not calling for heat? I think I need to wire these as two separate circuits because of the total current on 12 wire? Thanks for the help.