thermostat and garage door wire in conduit

[Andrew Thuswaldner]

Are you allowed to put your garage door opener wire and gas heater thermostat wire in the same conduit with 110V and 220V wires?

[Jim Becker]

Low voltage and high voltage is to be separated, to the best of my knowledge.

[Matt Ocel]

Low voltage and high voltage is to be separated, to the best of my knowledge.


That is correct.

[JohnT Fitzgerald]

same here.

when running LV wires in walls (cable tv, network, thermostat, etc) in walls, I also put them in different locations (not between the same studs)...this way, when doing anything with/near the low voltage wires, you can be sure you won't hit a power line.

[David G Baker]

Don't know if there is a problem if you tape the wires on the out side of the conduit if they have to follow the same path. I keep all of my low voltage and high voltage separate and on occasion run the low voltage wires through short pieces of conduit or PVC water pipe to protect them from physical harm.
I also do what JohnT does.

[Andrew Thuswaldner]

Thanks guys. Keeping them separate makes sense to me. Not sure I would have done it even if it was allowed. Having said that, in my experience the code never lets you do anything you that feels even slightly questionable from a safety standpoint.

[Rollie Meyers]

High voltage?? 600 volts and less is considered low voltage, if the wire is insulated to the higher voltage it could be done if some other conditions are met but it would be a bad idea IMHO.


A better discription would be Line Voltage to refer to 120 volt conductors.

[Jim Becker]

Rolie, my use of the term "low voltage" was referring to control and communication type wiring/circuits as compared to line voltage (120/240v). If I misspoke, it was not intentional.

[Rollie Meyers]

Rolie, my use of the term "low voltage" was referring to control and communication type wiring/circuits as compared to line voltage (120/240v). If I misspoke, it was not intentional.

Not a big deal :D 24V is low voltage but 120v is not high voltage it just must be respected.

And I hope everyone is having a wonderful weekend.

[Sonny Edmonds]

All conductors in a conduit must be insulated for the highest voltage being run in the conduit.
So if your thermostat wire is rated for , say 300 volts, you can run all the wires in the conduit, up to 300 volts. Low voltage (<50 volts), 120, and 240 can all be run together because they are all below 300 volts.
If your garage door wire, or thermostat wire, is NOT rated for 300 volts then NO you cannot legally run it in the same conduit with 120 or 240 volt circuits. :rolleyes:

[Dan Friedrichs]

+1 taping the wire to the outside of the conduit

[Duncan Horner]

All conductors in a conduit must be insulated for the highest voltage being run in the conduit.
So if your thermostat wire is rated for , say 300 volts, you can run all the wires in the conduit, up to 300 volts. Low voltage (<50 volts), 120, and 240 can all be run together because they are all below 300 volts.
If your garage door wire, or thermostat wire, is NOT rated for 300 volts then NO you cannot legally run it in the same conduit with 120 or 240 volt circuits. :rolleyes:

In addition, one must consider induced voltages on the t-stat wires, Unsure if the t-state wires use low AC voltage or not, but if you shove them in the pipe with higher voltage circuits, that's what they'll have on them.

Taped to the outside of the conduit, if it's metal, shields them from such 'ghost' voltages

[Sonny Edmonds]

The voltage isn't high enough, nor is the distance run long enough, for any appreciable induced voltage.
Had it been, the NEC would have erred on the side of safety.

Of course you could get out a meter and check for yourself.

One case I know of is where a rancher ran 3 1/2 miles of a single strand of wire on 40' poles on his property alongside of a 230 KV transmission line.
Effectively, an open air transformer.
With that, he was able to run a 1/2 HP pump. (After running it through a transformer to smooth it.)
The City of Los Angeles took him to court for stealing power. The judge ask if he had connected to the transmission line? No, he hadn't made any connection.
So the judge ruled that it was the power companies responsibility to keep their power in the power line so he couldn't get the induced voltage from it.
The rancher won.
But it took 3 1/2 miles of poles, insulators, wire, and equipment to induce enough current to run a small 1/2 HP pump.

To run 20-30 feet, alongside of some other wires is not going to induce more than possibly a few thousandths of a volt in the other wiring.
Not enough to even consider as a problem.

[Duncan Horner]

To run 20-30 feet, alongside of some other wires is not going to induce more than possibly a few thousandths of a volt in the other wiring.
Not enough to even consider as a problem.

You can get on the order of 24V induced alongside these line voltages, you won't get much current, but these voltages are possible, I've personally measured them. I believe that the t-stat wires are for sensing/switching and not powering the equipment, thus voltages that can't support a lot of current *could* still be a problem.

More info

http://repairfaq.ece.drexel.edu/REPAIR/F_appfaqj.html#APPFAQJ_019

http://forums.mikeholt.com/showpost.php?p=725193&postcount=17

I presume it's for this same reason that you can't separate the conductors of a 3 phase circuit, in that the flux does funny things in metal pipe, not all of which make too much sense

I personally would separate the power and LV conductors.

All IMHO and YMMV, I've been wrong before, and it'll probably happen again lol