can i add a 2nd switch to my furnace shut off ?

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  #1  
Old 07-19-07, 04:19 PM
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can i add a 2nd switch to my furnace shut off ?

oil fired steam furnace.

i have one emergency shut off switch at the door leading into the cellar from the outside. i would like to know if i can add a second emergency shut off switch upstairs.
i realize this is done for light fixtures, two switches controlling one lamp, but i wasnt sure if it was allowed for emergency shut offs.
also would like to know if there is one place that is easier to tie the new switch into then another.
and, the only way i know to wire three way switches for light fixtures is with 3 wire cable. i was wondering if i could avoid running 3 wire between the switches, since i only need either switch to turn the furnace off, i dont need to have one switch off and the other switch being able to turn the furnace on.

circuit is 2 wire BX type from breaker to a junction box. (used to be a second switch here, but they took it out when they replaced the furnace).
second 2 wire BX goes from junction box to furnace.
third 2 wire BX goes from junction box to emergency switch.

here is how they are connected,

one wire from breaker(dont know the color) and the white from the furnace are wirenutted together.
black from emergency switch and other wire from breaker are wirenutted together.
white from emergency switch and black from furnace are wirenutted together.

i would like to run ROMEX type to the new switch from the junction box, because i think that is the easiest way. it is also the shortest route.

so, can i do this ?
 
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  #2  
Old 07-19-07, 04:22 PM
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Don't know whether it is legal or not but it is certainly possible add a second switch in series with the first. You could do it by running a cable from either the existing switch or the junction box where all the cables meet. Only a two wire cable would be required.
 
  #3  
Old 07-19-07, 04:26 PM
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thanks joed

that is what i was thinking, now i just need to find out if it is legal/safe/sane.
 
  #4  
Old 07-19-07, 04:34 PM
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I believe that a second switch in series with the first one is legal. The reason for the switch is to be able to shut the furnace off without having to enter the room where it is located. You just reach inside the door and turn it off.

With a second switch in series you will have to have both switches ON to run the furnace.

You can wire the second switch from the first, or right from the furnace.
 
  #5  
Old 07-20-07, 04:07 PM
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so i can wire it the way i planned ?

2 wire from the junction box to the new switch. connect the new switch wire to the same wires as the old switch, black wire from new switch connects to black wire from old switch and breaker. white from new switch to white from old switch and black from furnace. ground from new switch to metal junction box.

this will give me two switches that both have to be on for the furnace to work, but either can turn the furnace off, correct ?
 
  #6  
Old 07-20-07, 04:23 PM
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Your existing setup sounds wrong. However, your description is very hard to follow.

Further, what you propose sounds wrong.

At the junction box where you used to have a switch connect the two hot wires to the switch. Done.

If you describe your existing setup better, I can help you make sure it is correct (and safe).
 
  #7  
Old 07-20-07, 05:03 PM
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let me try to explain it this way.

its just a furnace with an emergency shutoff switch.

i want to add a second switch.

i know i can just add it to the same wires the existing switch is connected to. i have a junction box where the wires from the breaker, furnace and existing switch meet.

the question is, can i do it that way ?

i dont want a threeway switch, i just need a second emergency shutoff switch.
 
  #8  
Old 07-20-07, 05:07 PM
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Yes. The following connections should b made at this junction box:

All ground wires connected together and to the metal box and to the new switch.

Black power wire to the white wire to the switch.

White power wire to the white wire to the furnace.

Black switch wire to one terminal of the switch.

Black furnace wire to the other terminal of the switch.
 
  #9  
Old 07-20-07, 05:51 PM
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thats not the way the existing switch is wired. i would have to rewire the existing switch.

lets try it this way.

if i trace the wires from the existing switch to the junction box, remove the wire nuts from those wires, add the same color wires from the new switch to the wires from the existing switch, replace wire nuts, i will have two switches that will turn the furnace off, correct ?

then the ground from the ROMEX gets attached by a screw to the metal junction box on one end, and the switch on the other.
 

Last edited by xfrank12; 07-20-07 at 05:51 PM. Reason: add details.
  #10  
Old 07-20-07, 06:01 PM
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The original switch is wired wrong. It works electrically, but is wrong per code.

What part of "your description is very hard to follow" are you nor grasping. Your description does not make sense and is hard to follow.

Tell me exactly what you have and I will help.

I have already told you hot to electrically wire it. Follow my directions and it will work as you want. Follow your directions and it won't, at least not as far as I can tell. If it does work with yoru directions, it will be wired incorrectly per code.
 
  #11  
Old 07-20-07, 06:38 PM
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certainly not trying to argue with you, if i knew what i was doing i wouldnt be here, i just cant believe what i have is wrong, because it works.

of course, the furnace guys had to install a new furnace, so they may have switched wires in the junction box.

i can easily follow your instructions, it just means i have to switch the wires around in the junction box.

before i do that, here is a diagram that might explain it better.


black
------------------------ | wires from breaker
------------------------| |
white | |
| |
| |
| |
| |
black | |
================= { } junction box

white * *
* *
wires from existing * *
switch * *
* *
* * black
****************
*****************
white
wires to furnace


one wire from breaker( cant tell color) and the white from the furnace are wirenutted together.
black from emergency switch and other wire from breaker are wirenutted together.
white from emergency switch and black from furnace are wirenutted together.

so you are saying, the wiring of the existing switch is wrong and need to change that before i add a switch ?
 
  #12  
Old 07-20-07, 06:41 PM
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forget the diagram, it doesnt post the way it is written.

just read this part.

one wire from breaker( cant tell color) and the white from the furnace are wirenutted together.
black from emergency switch and other wire from breaker are wirenutted together.
white from emergency switch and black from furnace are wirenutted together.

so you are saying, the wiring of the existing switch is wrong and i need to change that before i add a switch ?
 
  #13  
Old 07-20-07, 07:36 PM
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The wiring from/to the switch is backwards. Just swap the two switch wires and it will be correct.

The black power wire needs to connect to the white switch wire. The black switch wire needs to connect to the black furnace wire.
 
  #14  
Old 07-20-07, 09:56 PM
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thanks.

it wont let me post just "thanks", so i have to add this line.
 
  #15  
Old 07-21-07, 05:44 AM
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You are welcome.

Understand that the way your switch was wired was the same electrically as the proper solution. It just was not to code. This is a safety issue and as long as it;s not messed with would have remained fairly safe. The problem comes into play when someone later on tries to modify or work on the circuit. They MAY get confused by the strange wiring.
 
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