# Is this right



## spec grade (Oct 8, 2009)

I was looking in to relocating feed to 120 volt damper motor for a large exhaust duct being relocated.Damper motor and 24 signal wiring come from a building management system.120 volt damper motor is wired with Belden 88760 cable(18-2 twisted shielded)has 300 volt rating.My gut says that can't be legal.Like I said it is part of a control system but just does not seem right.Am I missing something?


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## RIVETER (Sep 26, 2009)

spec grade said:


> I was looking in to relocating feed to 120 volt damper motor for a large exhaust duct being relocated.Damper motor and 24 signal wiring come from a building management system.120 volt damper motor is wired with Belden 88760 cable(18-2 twisted shielded)has 300 volt rating.My gut says that can't be legal.Like I said it is part of a control system but just does not seem right.Am I missing something?


Is that a heavy duty shaded pole motor?


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## MDShunk (Jan 7, 2007)

ummm... maybe. What's feeding the 18-2? What's the construction type of the building?


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## cdnelectrician (Mar 14, 2008)

Hmm my guess would be no. Unless this is a class 2 circuit and I doubt it is. From what you said the control and power are seperate cables right?


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## spec grade (Oct 8, 2009)

It,s not a heavy duty motor.18-2 is fused down in control cabinet to one amp.Cables in pipe entire length.Yes control and 120 volt seperate cables same raceway.


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## cdnelectrician (Mar 14, 2008)

spec grade said:


> It,s not a heavy duty motor.18-2 is fused down in control cabinet to one amp.Cables in pipe entire length.Yes control and 120 volt seperate cables same raceway.


I really do not see a problem with that. It is in conduit and it's fused at 1 amp.


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## spec grade (Oct 8, 2009)

CDN,Do you think it's legal.I wouldn't do it that way.It looks like a low voltage 24 volt cable.I dont understand why they didn't just pull thhns to it.


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## RIVETER (Sep 26, 2009)

spec grade said:


> CDN,Do you think it's legal.I wouldn't do it that way.It looks like a low voltage 24 volt cable.I dont understand why they didn't just pull thhns to it.


It's not too late to make it right.


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## spec grade (Oct 8, 2009)

I agree when I refeed it I will pull in thhn.This was part of major plant upgrade done by an engeneering firm and another contractor.Another thing I do not understand is that 88760 cable is more money than thhn.


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## cdnelectrician (Mar 14, 2008)

spec grade said:


> CDN,Do you think it's legal.I wouldn't do it that way.It looks like a low voltage 24 volt cable.I dont understand why they didn't just pull thhns to it.


 
I am not familiar with the NEC and if it were me doing it I would have used THHN. But I do see that done here sometimes ( Canada ). I've had arguments about this with other guys at work. That cable would be OK used for a power limited circuit at 120 volts (class 2) but in this case the circuit is only fused down to 1 amp so it is not a power limited circuit.

To tell you the truth I am not entirely sure because I have never considered using cable like that for such an application. Maybe someone else with more knowledge of the NEC might have a better answer!


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## cdnelectrician (Mar 14, 2008)

spec grade said:


> I agree when I refeed it I will pull in thhn.This was part of major plant upgrade done by an engeneering firm and another contractor.Another thing I do not understand is that 88760 cable is more money than thhn.


It was probably close by, pretty popular cable for control work.


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## spec grade (Oct 8, 2009)

Thanks cdn I did not realize you were from canada.I appreciate your input.I know the answer lies in art 725 of nec.I still want to know if it is legal but will still use thhn for it.


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## miller_elex (Jan 25, 2008)

What? They fused the wire? 18 is good for alot more than one amp.

It's cheaper to buy a 24vac actuator and re-use the same cable.

There are 24V actuators with some super high torques you know.


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## mattsilkwood (Sep 21, 2008)

It sounds like they just put tray cable in a pipe. I dont see anything wrong with it. 
As long as the insulation rating is good and it sounds like it is, you're fine.


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## miller_elex (Jan 25, 2008)

If you want to have 120v and low voltage in the same raceway, it all needs to be 600v wire, not just the 120v. Even then, its a bad idea.

You should probably pull the 120V out of the existing pipe, and refeed 120V from the nearest available general purpose circuit. If there is no interlock between a damper status and the ef start stop, it would be a good idea.


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## spec grade (Oct 8, 2009)

as part of this job they are adding two more dampers.Plan to install a second pipe one for 120,one for 24.This is all on a roof.Ducts are 30 inch diameter.As far as changing damper motor to 24 volts.I suggested that today cust does not want.


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