Our home is heated with baseboard heaters controlled by wall mounted
thermostats. With a thermostat removed {and the circuit presumably
broken} my voltmeter still detects a small AC voltage at the terminals
on the baseboard heater. If these wires touch, they will spark. Why
is there a voltage going to the heater with the thermostat off or
removed? Does this mean the heaters are consuming power even if the
thermostats are off?



















/

wrote in message
ups.com...
Our home is heated with baseboard heaters controlled by wall mounted
thermostats. With a thermostat removed {and the circuit presumably
broken} my voltmeter still detects a small AC voltage at the terminals
on the baseboard heater. If these wires touch, they will spark. Why
is there a voltage going to the heater with the thermostat off or
removed? Does this mean the heaters are consuming power even if the
thermostats are off?


Does your thermostat break both sides of the line or only one side? My
heaters are 240 vac with double pole line voltage wall thermostats so
removing a thermostat isolates the heaters 100%. Assuming 240 vac, if you
are breaking only one side of the line, then one side will still be live and
you could be getting a small spark due to heater leakage to ground. Have you
measured the voltage to ground from each of the wires with the thermostat
off? If your thermostat is switching only 24 volts through a relay, then it
gets a little more complex. Do you have #10 wire going to your thermostats?
Two wires or four?

Bob

Bob:

I just measured our voltage at the baseboard heater and it appears to
be 240 volts. The thermostats are two wire types, so they must only
break one side of the line. Oddly, with the thermostat turned off, I
get different voltage readings on my voltmeter depending on the range I
have set {60 volts at 600 volt range, 4 volts at 15 volt range}.

When I measure the voltage between the ground wire and the live wires I
get 120 volts with one and 0 volts with the other.

Oddly, with the thermostat turned off, I
get different voltage readings on my voltmeter depending on the range I

have set {60 volts at 600 volt range, 4 volts at 15 volt range}.


That is an idication that the merter is reading a very small leakage
current, even the small load of the meter is enough to reduce the
voltage...

Use a small light bulb as a load and measure the voltage across the
bulb. If there is a real voltage there, the bulb will light and you
will get a real reading on the meter.

Mark

also....your thermosdat switch may have a spark supression circuit
which may be a small capacitor and reistor across the contact.....this
will pass a very small amount of current that will register on your
meter and may be able to casue a visable spark...but there is no real
power so no need to worry that tthe heater is wasting
electricity...again use a small light bulb as a load.....if there is
realy power there, the bulb will light... you may want to use a 240
volt bulb

Mark

"Borealis" wrote in message
ups.com...
Bob:

I just measured our voltage at the baseboard heater and it appears to
be 240 volts. The thermostats are two wire types, so they must only
break one side of the line. Oddly, with the thermostat turned off, I
get different voltage readings on my voltmeter depending on the range I
have set {60 volts at 600 volt range, 4 volts at 15 volt range}.

When I measure the voltage between the ground wire and the live wires I
get 120 volts with one and 0 volts with the other.


Many good suggestions. I might add to keep in mind that with it breaking
only one side of the line, you still have a live wire there when the
thermostat is off, or with the thermostat removed. Be aware that 120 volts
from the line you don't break will feed back through the heater to the off
side of your thermostat and voltage may appear where you don't expect it. So
if you're going to do any work on the heaters or the thermostat, be safe and
turn the circuit off at the breaker. Even with the double pole thermostat
that I have, I kill the power at the breaker if I'm going to work on the
heaters.

Bob

wrote:
Our home is heated with baseboard heaters controlled by wall mounted
thermostats. With a thermostat removed {and the circuit presumably
broken} my voltmeter still detects a small AC voltage at the terminals
on the baseboard heater. If these wires touch, they will spark. Why
is there a voltage going to the heater with the thermostat off or
removed? Does this mean the heaters are consuming power even if the
thermostats are off?



















/

Hi,
Are you using DVM? Really you should measure with circuit breaker off to
the heater.