baseboard heaters & double pole thermostats

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  #1  
Old 09-17-02, 12:39 PM
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baseboard heaters & double pole thermostats

I am installing two banks of baseboard heaters. Each bank will draw approx. 15 amps. Each bank will be on a separate circuit (220 VAC w/ 20 AMP breaker). Typically a single pole thermostat will break one leg of of a 220 circuit and a double pole thermostat breaks both. Can I wire a double pole thermostat to break one leg from each circuit so as to control both banks of heaters from a single thermostat?
 
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  #2  
Old 09-17-02, 01:37 PM
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Use a low-voltage thermosat that controls a hi-wattage contactor designed for switching 220 volt electric-heat circuits.Search the "Electromode" WS or visit an electrical-supply house for specific info.-----Good Luck!!!
 
  #3  
Old 09-17-02, 05:21 PM
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Thermastat:

No you can not, Sorry, This is not safe, Even A single pole thermastat is not allowed on a 240 volt heater.
 
  #4  
Old 09-17-02, 06:09 PM
Wgoodrich
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aphares I believe you are thinking low voltage thermostats. I suspect the post was intending on using a baseboard heater thermostat rated 20 amp 240 volt.

A 20 amp 240 volt double pole thermostat or a 20 amp 240 volt single pole thermostat are listed and labeled for use with baseboard heaters whether wall mounted or heater mounted.

However you are correct that you are not allowed to install two 20 amp 240 volt branch circuits through one double pole thermstat. Don't believe you will find the listing and labeling allowing 40 amps at 240 volts [two 20amp 240 volts equals 40 amp loading] of branch circuits to pass through a 20 amp rated device.

Wg
 
  #5  
Old 09-17-02, 06:24 PM
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424.20

424.20 Thermostatically Controlled Switching Devices.

(A) Serving as Both Controllers and Disconnecting Means. Thermostatically controlled switching devices and combination thermostats and manually controlled switches shall be permitted to serve as both controllers and disconnecting means, provided all of the following conditions are met:

(1) Provided with a marked “off” position

(2) Directly open ((all ungrounded conductors)) when manually placed in the “off” position

(3) Designed so that the circuit cannot be energized automatically after the device has been manually placed in the “off” position

(4) Located as specified in 424.19
 
  #6  
Old 09-17-02, 06:44 PM
Wgoodrich
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424.20 Thermostatically Controlled Switching Devices.
(B) Thermostats That Do Not Directly Interrupt All Ungrounded Conductors. Thermostats that do not directly interrupt all ungrounded conductors and thermostats that operate remote-control circuits shall not be required to meet the requirements of 424.20(A). These devices shall not be permitted as the disconnecting means.

424.19 Disconnecting Means.

(C) Unit Switch(es) as Disconnecting Means. A unit switch(es) with a marked “off” position that is part of a fixed heater and disconnects all ungrounded conductors shall be permitted as the disconnecting means required by this article where other means for disconnection are provided in the types of occupancies in

(3) One-Family Dwellings. In one-family dwellings, the service disconnecting means shall be permitted to be the other disconnecting means.

Does this hit the mark?

Wg
 
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Old 09-17-02, 07:15 PM
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Diconnect:

424.19 Requires a disconnect for all ungrounded conductors

424.19(B) States the branch circuit breaker or switch can serve as the disconnect, if within site, or can be locked out.

So we can determine if they are not within site of, then a disconnect must be required.

424.19(C) Allowes the switch to serve as the disconnect if it is (Part of the Fixed heater) "Attached to". If the thermastat is then a wall unit it would fall under requirments of 424.20 (Stated above).
Saying a single pole is not allowed is not totally correct. Yes a single pole can be used on a 240 volt heater, but only if the requirments of the disconnect are meet first. I think 424.20(B) would back this last statement up.

Under the disconnect rule all ungrounded conductors have to be disconnected.
 

Last edited by aphares; 09-17-02 at 08:26 PM.
  #8  
Old 09-17-02, 07:54 PM
Wgoodrich
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After working with what I see in the Code and the last reply that I read, I am going to have to clarify along with Aphares is pointing out that a double pole thermostat will have to be used for the heaters in a certain room. A single pole thermostat may only be used if the breaker panel or other form of disconnect is also in sight of that or those heaters controlled by that single pole thermostat.

Good catch Aphares.

Wg
 
  #9  
Old 09-18-02, 02:00 PM
Guy
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I re-read the original poster's question and it appears that he was looking for a way to "control" (ie: maintain a temperature setpoint) two seperate circuits with a single double pole thermostat. Even if it were allowed electrically, this will not work because both poles of the thermostat are not controlled by the room temperature; only one is. The other is always "on" unless the dial is turned to the "off" position, so he would have one heater bank heating all the time...
 
  #10  
Old 09-19-02, 06:42 AM
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Thank You

This exchange has been very informative and helpful. Thanks for the help. Here is where I am at this point. I have purchased a Honeywell DP2030 Definte Purpose Contactor. It will be mounted next to the breaker panel supplying power to both circuits. This will satisfy the total diconnect issue. Each bank of heaters draw 14 AMPS so I feel comfortable with the 40 AMP resistive load rating for the contactor. The contactor will disconnect one leg of each heater circuit. The control circuit for the pickup coil is 24V and will be activated by a thermostat. I have a number of low voltage and line voltage thermostats (single and double). Which would you use in this application? I may put 2 LEDs on the junction box in which the contactor is housed indicating that state of each incoming line.

The Website for the DP2030 specs is:
http://customer.honeywell.com/gassys...or/dp1025.html

BTW: Guy is correct about the way a double pole line voltage thermostat works. Honeywell T498 specs:
http://content.honeywell.com/yourhom...stats/t498.htm
 
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Old 09-19-02, 07:27 AM
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Thank You

This exchange has been very informative and helpful. Thanks for the help. Here is where I am at this point. I have purchased a Honeywell DP2030 Definte Purpose Contactor. It will be mounted next to the breaker panel supplying power to both circuits. This will satisfy the total diconnect issue. Each bank of heaters draw 14 AMPS so I feel comfortable with the 40 AMP resistive load rating for the contactor. The contactor will disconnect one leg of each heater circuit. The control circuit for the pickup coil is 24V and will be activated by a thermostat. I have a number of low voltage and line voltage thermostats (single and double). Which would you use in this application? I may put 2 LEDs on the junction box in which the contactor is housed indicating that state of each incoming line.

The Website for the DP2030 specs is:
http://customer.honeywell.com/gassys...or/dp1025.html

BTW: Guy is correct about the way a double pole line voltage thermostat works. Honeywell T498 specs:
http://content.honeywell.com/yourhom...stats/t498.htm
 
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