Thermostat
- Thread starter easymoney
- Start date
- Status
Hendrix
Senior Member
- Location
- New England
At one time if the insulation was rated for, I think, 300vac. But I think they stopped that in 08. Anyway, I can't find it in the book.
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300.3(C) Conductors of Different Systems.
(1) 600 Volts, Nominal, or Less. Conductors of ac and dc circuits, rated 600 volts, nominal, or less, shall be permitted to occupy the same equipment wiring enclosure, cable, or raceway. All conductors shall have an insulation rating equal to at least the maximum circuit voltage applied to any conductor within the enclosure, cable, or raceway.
(1) 600 Volts, Nominal, or Less. Conductors of ac and dc circuits, rated 600 volts, nominal, or less, shall be permitted to occupy the same equipment wiring enclosure, cable, or raceway. All conductors shall have an insulation rating equal to at least the maximum circuit voltage applied to any conductor within the enclosure, cable, or raceway.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Then, why is there an issue with running the control wiring in the same raceway as the power conductors with standby generators?
See this cut sheet for General Cable, Carol Brand T'stat wire:
http://www.generalcable.com/NR/rdon...-B418-40F78331261D/0/Pg141_ThermostatWire.pdf
Seems to be rated 30V. Can't go in conduit with 120/240V operating voltage power cables.
This cable is rated 150V: http://www.generalcable.com/NR/rdon...-8707-74F7C24935AA/0/Pg142_ThermostatWire.pdf
But it can't go in conduit that has 240V operating voltage power cables.
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ceb58
Senior Member
- Location
- Raeford, NC
Cant give a code reference against it. But every one I have installed the mfg. instructions state the control wireing is not to be ran with phase conductors or in the cond. with power for the batt. charger/block heater. There thing is RF/MF interfering or giving false start information to the gen. We install 4pr., 22 ga stranded, individually shielded, direct bury cable in its own conduit.
- Location
- Massachusetts
- Location
- Illinois
- Occupation
- retired electrician
You have to look at the FPN that follows that code section. Most HVAC controls are NEC Class 2 circuits and are covered by the rules in Article 725. Those rules prohibit installing Class 2 control circuit wires in the same raceway as the power circuit wires.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I agree. The power supplies are almost always class 2. That requires separation regardless of the insulation value.
arits74
Senior Member
- Location
- dixie arkansas
- Occupation
- working owner electrician
just hooked up a generac 20kw last week and the installation manual said if the control wires were rated for 600 volts then they could be ran in the same conduit with the power wires,but we also hooked up a 35 kw last year that said not to run the control with the power wires.
DARUSA
Senior Member
- Location
- New York City
Class 2 circuits
Class 2 circuits
Class 2 circuit can not be in the same raceway with power circuit but you can reclassify as a class 1 circuit and use chappter 3 as a your wiring methods.
Insulation should be rated for the maximum voltage.
Where it is necessary to locate Class 2 or Class 3 circuits inside the same cable or raceway as
a Class 1 circuit, 725.130(A), Exception No. 2, permits a Class 2 or Class 3 circuit to be
reclassified and installed as Class 1, providing that the Class 2 or Class 3 marking is removed,
that overcurrent protection is provided in accordance with 725.43, and that the reclassified
circuit maintains separation from other Class 2 and Class 3 circuits in accordance with
Class 2 circuits
Class 2 circuit can not be in the same raceway with power circuit but you can reclassify as a class 1 circuit and use chappter 3 as a your wiring methods.
Insulation should be rated for the maximum voltage.
Where it is necessary to locate Class 2 or Class 3 circuits inside the same cable or raceway as
a Class 1 circuit, 725.130(A), Exception No. 2, permits a Class 2 or Class 3 circuit to be
reclassified and installed as Class 1, providing that the Class 2 or Class 3 marking is removed,
that overcurrent protection is provided in accordance with 725.43, and that the reclassified
circuit maintains separation from other Class 2 and Class 3 circuits in accordance with
- Location
- Massachusetts
That is true but once you do that the entire circuit must be treated as class 1.
So if you run the T-stat wire with the power wires for the final 10' at the boiler the entire run to the thermostat would have to be in NM, MC Pipe etc.
The T-Stat would have to conceal the terminals most likely by mounting it to a electrical box not just fastened to the wall.
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