On Feb 19, 12:32*pm, "RonABC" wrote:
I am about to add electric baseboard heat to a finished attic space in a
house that I own.

The wiring diagrams in a book that I have and on the Internet show to create
a 220/240-volt system using a 12/2 feed up to the heater(s), with 12/3 going
from the heater to the thermostat. *I assume that means that at the panel
box there would be a double breaker to create the 220/240-volt, and that the
white wire would be coded at the panel and at the heater to be black. *But,
that seems a little strange to me.

Is that how it is supposed to be done, or is it better or more correct to
run 12/3 as the feed and use the black and red wires as the hot wires?

Assuming your thermostats are 230 volt 'line voltage type' ?????

Also don't know why you need 3 conductor; either from panel to
thermostat or thermostat to heater!

More normal (and exactly how this house 1970 is wired) is 12-2 red/
black (with a bare ground conductor of course).

Black/white can be used provided the white is colored or taped (red
nail polish will do) to identify that it is hot (not neutral!).

You are correct, the red and black are connected through a double-pole
circuit breaker for #12 AWG that's a 20 amp DP breaker. Don't forget
the ground connection at each point also. For 230 there is no neutral.
Use standard wiring practice; insurance companies (both for property
and life insurance) can be picky!!!!!!!

With some (double pole thermostats) both red and black connect
'through' the thermostat. Most of my original ones do so.

But I have one or two that are single pole; in that case the black
goes through the thermostat and the red is connected straight through.

Make sure you thoroughly understand how the thermostat must be wired
also that they are the correct type. There have been cases where
people have hooked up low voltage thermostats to 230 volt line voltage
and blown the sh** out of them. In one case starting a small fire!

Low voltage thermostats are commonly used to control the low voltage
controls of furnaces etc. Or they can, using extra hardware (control
relays) control line voltage heaters. That then becomes a matter of
why use relays, where to mount them and how to get low voltage wire
from them to the 'low voltage thermostats'! Different discussion
altogether.

BTW we have found electric baseboard heaters and line voltage
thermostats very reliable. Since 1970 we have less than $100 in
maintenance. Two thermostats and one circuit breaker.

Any doubts get advice/help. In this area we have had three fatalities
(all children!) and a total of 3 fires all blamed on electrical
problems prior to Feb 15th, this year of 2009!

No matter what heating is used do not let people sleep in areas
without escape routes; whether that is basements or attics etc. Equip
(for only a few dollars) any new areas with smoke detectors.