I have 240V baseboard heaters with the termostat inside the heater. I
want to put wall switches in the same place as the light switches so
that I can turn off the heaters when I leave the room without getting
down on the ground to adjust the thermostat. I know that a single pole
switch will work but I wanted to know if there was any reason the code
required a double pole switch? Thanks!
The baseboard heaters are 2000W. If I put 2 of them on the same 20A
circuit I am at 83% of the rated breaker capacity (I am using standard
Siemens breakers). Do I really need to put each one on its own
Thank you for your time,
You cannot exceed 80% of the wire rating or of the breaker rating? I
thought it was of the breaker rating? And my real question is: are
baseboard heaters considered intermittent loads?
If the wire is properly matched, it works out to both.
And my real question is: are
What is intermittent about a heating element that maybe on from a few
minutes to hours at a time?
I'm glad I'm not your tenant. You seem to want to cheap out on this and
potentially cause a serious safety situation. Use the right double pole
switch, use the right wiring.
120V circuit has a neutral and a hot; if you stand in a bath tub and touch
the two wires one by one, you will get shocked by the hot, and not by the
240V circuit has no neutral; it has two hots (each one is 120V relative to
ground). If you touch the two wires one by one, you get shocked twice.
If you switch off only one hot, then the heater wiring is still carrying
120V. This is potentially dangerous.
I fail to understand why it is dangerous for the wire to be carrying
120V into the heater. So what? The (optional add-in) integrated
thermostat only breaks one pole. Are you saying it is dangerous?
Based on your posting alone it appears that if one is dangerous then
the other must be as well.
Do it if you want to; it is neither legal nor safe.
With a switch off, there is to be no voltage at a device. With a single
pole switch, someone working on the heater will be very surprised.
Your heaters could easily be on for hours at a time. Do you think that is
Do what you what, but don't hope that people will tell you it is okay.
Ah, but it is. Call it crazy, but the NEC (and I believe the CEC
as well) permit the use of single pole thermostats with 240V heaters.
I don't like it either, and when installing a heater, I'll use
a two pole thermostat.
But, anybody fiddling with the wires of a 240V heater, relying
_only_ on a thermostat to shut power off, probably deserves what
As an interesting sidenote: somewhat akin to the special ampacity ruleso
for motors, the CEC has special provisions for dedicated electric heater
While you cannot exceed the 80% rule for the breaker, you can load the
wire to 100% of its rating.
In other words, if you have a 15A heater on 120V, you can use
a 20A breaker and 14ga wire.
Which suggests to me that the continuous 80% ampacity limit is largely
for the breaker's benefit, not the wire.
This doesn't apply to the NEC.
Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
What you are saying is true but I expect code requires a double pole.
Someone working on the unit would not depend on the thermostat to remove
all power but would most likely expect it to be removed by the switch.
Kind of like power to a lamp with a non polarized plug being plugged
into a switchable socket. It is possible for the lamp to have voltage
even with the switch turned off.
Yeah, but as I posted, I don't know where my mind what when I made that
last statement. Immediately after I hit the send button I realized what
I had said. With the switch off there should not be any voltage on the
If plugged into an ordinary socket it could have voltage on the outside
rim of the socket.
I am happy as (insert expletive here) that you are NOT my landlord.
You've asked nearly the exact same question three times. You must be a real
FWIW, back when I rented, I (as the tenant) was responsible for the
He's probably too cheap to convert that apartment to separate metering
so the tenant can pay for the electricity, and would then also have an
incentive not to waste it.
Or, maybe he's renting an "illegal apartment" in an area zoned only for
single family housing and can't do that. <G>
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