Type-NM to furnace secured to PVC vent pipe

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tonype

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New Jersey
Shouldn't Type-NM be in conduit or some other form of protection for drop down to furnace? Here is a case where it is attached to the PVC pipe of a high-eff furnace vent.
 

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GoldDigger

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I see two potential problems:
1. Probably not protected adequately from physical damage at a low height from floor, but not clear from picture.
2. I would need to know more about the outside temp of the concentric PVC to see whether the ambient temp for the NM would be other than room temperature.
Same concern about proximity to duct unless that is a return.
 
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ActionDave

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Since the jacket and conductor insulation for NM B are both PVC I'd think it would be OK strapped to the pipe. As far as I'm concerned I can strap to it.

No furnace guys better not be strappin' no thermostat wire to any of my conduit though.
 

GoldDigger

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Since the jacket and conductor insulation for NM B are both PVC I'd think it would be OK strapped to the pipe. As far as I'm concerned I can strap to it.

No furnace guys better not be strappin' no thermostat wire to any of my conduit though.
I am not at all concerned about directly melting the insulation, just the possible ampacity correction. :)
I suspect you would not strap wiring to a hot water pipe, for example.
 

dfmischler

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Location
Western NY
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Facilities Manager
No furnace guys better not be strappin' no thermostat wire to any of my conduit though.

I thought Class 2 control cable may be attached to the conduit if it serves the circuit in the conduit. If so, that would make it OK to strap thermostat wire to the conduit that feeds power to the furnace. Has this changed?
 

infinity

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I thought Class 2 control cable may be attached to the conduit if it serves the circuit in the conduit. If so, that would make it OK to strap thermostat wire to the conduit that feeds power to the furnace. Has this changed?

You're correct and it's still in the NEC.

300.11(B)(2) Where the raceway contains power supply conductors
for electrically controlled equipment and is used to sup-
port Class 2 circuit conductors or cables that are solely
for the purpose of connection to the equipment control
circuits
 

Canton

Senior Member
Location
Virginia
Occupation
Electrician
I thought Class 2 control cable may be attached to the conduit if it serves the circuit in the conduit. If so, that would make it OK to strap thermostat wire to the conduit that feeds power to the furnace. Has this changed?

Its code compliant.....but aint no nasty HVAC guys gonna strap their thermostat wire to my pipe...:D
 
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