On Sun, 29 May 2016 03:47:25 -0000 (UTC), Diesel
wrote:


Sat, 28 May 2016 23:17:05 GMT in alt.home.repair, wrote:

On Sat, 28 May 2016 20:04:33 -0000 (UTC), Diesel
wrote:


Thu, 26 May 2016 05:50:22 GMT in alt.home.repair, wrote:

"Continuous load" means you size the circuit to 125% of total
load (14.6*1.25=18.25a)
so 18.25a is OK on a 12 ga wire with a 20a breaker

You're going over the 80% trade standard load (16amps on a 20amp
circuit) at that point,

Excuse me but the load is 14.6a. The 18.25a IS 125% of the load so
the 80% has been accounted for.

The load is 14.6A under perfect conditions of a wire 100ft or less
in total length, yes. However, if the last heater happens to be a
bit further away from the panel than 100ft as the OP suggested,
there's a real risk of voltage drop to the last heater with
the others running because the 12/2 wire just can't provide the full
load that far out to the last device. A voltage drop will increase
the amount of amps required by that heater to do it's job. The 12/2
isn't going to appreciate that and neither will the breaker. It will
tolerate being over 20amps until it heats up enough to trip.

The heater is not going to decrease it's resistance and draw more
current to compensate for the voltage drop. It will just be a slightly
smaller heater. Heaters are rated at 120, 208 or 240v. If the voltage
is lower, the heater will just have a lower output.
An example is an oven element. At 240v it is rated 3600w, at 208 it is
only 2700w