Unit Heater Wiring Scenario

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mstrlucky74

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So if you had two temp unit heaters that required #12 wireand could be run in mc cable would you be able to run out 12/3 as I show in oneof the pics then mount box and continue with 12/2.?Would there be an issue withthe ground in the 12/3. Would each unit heater need a separate ground thuseliminating the 12/3 scenario? Thanks.
 

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mstrlucky74 said:
So if you had two temp unit heaters that required #12 wireand could be run in mc cable would you be able to run out 12/3 as I show in oneof the pics then mount box and continue with 12/2.?Would there be an issue withthe ground in the 12/3. Would each unit heater need a separate ground thuseliminating the 12/3 scenario? Thanks.
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I think NEC 2014 210.4 would allow this.
 
mstrlucky74 said:
So if you had two temp unit heaters that required #12 wireand could be run in mc cable would you be able to run out 12/3 as I show in oneof the pics then mount box and continue with 12/2.?Would there be an issue withthe ground in the 12/3. Would each unit heater need a separate ground thuseliminating the 12/3 scenario? Thanks.
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Need more information. Are you installing a 120/240 volt line to one UH and continuing with a straight 240 volt line to the other UH?
 
Knuckle Dragger said:
Need more information. Are you installing a 120/240 volt line to one UH and continuing with a straight 240 volt line to the other UH?
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I think the heaters are both 120V. He is bringing a 120/240V MWC (L1, L2, N) into the first heater but only connecting L1 and N. L2 and N continues to the second heater. I don't see an issue with this, if that is what he is doing.
 
Thanks all. Now I just have to compare the two cost wise. There will be more labor to mount box and splice that wouldn't have to be done if I ran two separate 12/2 but there will also be less supports. It's a wide open exposed space so pulling the cables will be easy.
 
mstrlucky74 said:
Thanks all. Now I just have to compare the two cost wise. There will be more labor to mount box and splice that wouldn't have to be done if I ran two separate 12/2 but there will also be less supports. It's a wide open exposed space so pulling the cables will be easy.
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mstrlucky, one estimator to another, good luck on that project! You are analyzing that down to the pennies!
 
mstrlucky74 said:
Thanks all. Now I just have to compare the two cost wise. There will be more labor to mount box and splice that wouldn't have to be done if I ran two separate 12/2 but there will also be less supports. It's a wide open exposed space so pulling the cables will be easy.
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What kind of a heater is this? What is it used for? Can you put both 12/3 and 12/2 inside the first heater?
 
mstrlucky74 said:
So if you had two temp unit heaters that required #12 wireand could be run in mc cable would you be able to run out 12/3 as I show in oneof the pics then mount box and continue with 12/2.?Would there be an issue withthe ground in the 12/3. Would each unit heater need a separate ground thuseliminating the 12/3 scenario? Thanks.
Click to expand...

Can I ask you something?


You ask us things all the time and many of us answer these questions.

So my question to you is why as an estimator are you trying to wire the building?:huh:


Out in the field I have never for one moment considered how the estimator thought the job could be done. I follow the prints and make my own choices on how to wire things.
 
kwired said:
Chances are very great that a disconnect is needed near the heater, make the splice there.
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kwired said:
If motor is over 1/8 HP, no. See 422.31(C).
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It looks like there are about three seperate post about these heaters and the first post gives more information.

The first post says these are hot water type heaters and would only use the 120V for a 1/20th hp motor (fan) and a solinoid to control water flow.

If the plans spec a disconnect you would either have to install one or get the plans changed.

I'm thinking that you could probably put about four of these heaters on one circuit. That would be a big cost saveing. Have to see the heater instructions but a 1/20th hp motor and a solinoid isn't going to take much power.
 
iwire said:
Can I ask you something?


You ask us things all the time and many of us answer these questions.

So my question to you is why as an estimator are you trying to wire the building?:huh:


Out in the field I have never for one moment considered how the estimator thought the job could be done. I follow the prints and make my own choices on how to wire things.
Click to expand...


And i I appreciate all the feedback IW. I think my questions generate dialogue between members that may help, in some way, others. At least that how I look at it because I want to be able to contribute but I can't as most on here have more knowledge than myself.

i think as an estimator you have to know how things are wired, hence all my questions. im familiar with a lot of wiring methods but also want to make sure I'm figuring things correctly and get as close to actual field install as possible. That how I approach it.
 
growler said:
It looks like there are about three seperate post about these heaters and the first post gives more information.

The first post says these are hot water type heaters and would only use the 120V for a 1/20th hp motor (fan) and a solinoid to control water flow.

If the plans spec a disconnect you would either have to install one or get the plans changed.

I'm thinking that you could probably put about four of these heaters on one circuit. That would be a big cost saveing. Have to see the heater instructions but a 1/20th hp motor and a solinoid isn't going to take much power.
Click to expand...

Agreed, thanks.
 
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