Dimming Wiring

[steve66]

It seems to me that I am allowed to reclassify the dimming wire, and run it with the power conductors.

I'm thinking the MC cable with the separated wired for dimming is for when someone can't reclassify the dimming wires, doesn't want to reclassify the dimming wiring, or for jurisdictions where codes or the AHJ doesn't allow this.

After all, all of my Class 2 wiring would be in conduit, and the terminations would still be enclosed with the power conductors at the light fixture and at the dimmer box.

Anyhow, for this particular project I wound up specifying wireless controls.

 

[hbiss]

I was proposing UF for the LV (or tray cable if you like) and THWN for the line voltage. Still OK?

No. The individual conductors in conduit make it a run of conduit per Chapter 3. You can't pull LV wiring into that conduit with the line voltage conductors.

However, if you pull UF for the line voltage, the UF is a listed cable assembly making the conduit a chase. Now you can pull anything for the LV even CAT5.

You see the difference between individual conductors and a cable assembly?

-Hal

 

[GoldDigger]

No. The individual conductors in conduit make it a run of conduit per Chapter 3. You can't pull LV wiring into that conduit with the line voltage conductors.

However, if you pull UF for the line voltage, the UF is a listed cable assembly making the conduit a chase. Now you can pull anything for the LV even CAT5.

You see the difference between individual conductors and a cable assembly?

-Hal

And just where does that leave the dual voltage cable assembly in a common outer sheath?

 

[hbiss]

It seems to me that I am allowed to reclassify the dimming wire, and run it with the power conductors.

I'm thinking the MC cable with the separated wired for dimming is for when someone can't reclassify the dimming wires, doesn't want to reclassify the dimming wiring, or for jurisdictions where codes or the AHJ doesn't allow this.

After all, all of my Class 2 wiring would be in conduit, and the terminations would still be enclosed with the power conductors at the light fixture and at the dimmer box.

Anyhow, for this particular project I wound up specifying wireless controls.

You might want to read 725.136 carefully and remember that the power conductors are not Class 1.

-Hal

 

[hbiss]

And just where does that leave the dual voltage cable assembly in a common outer sheath?

A factory listed assembly.

-Hal

 

[wwhitney]

No. The individual conductors in conduit make it a run of conduit per Chapter 3. You can't pull LV wiring into that conduit with the line voltage conductors.

Yes, I see that 725.136(A) prohibits that, and on its surface would seem to prohibit MC luminary cable also. But the manufacturers of MC luminary cable cite 725.136(I) as permitting its use. If MC luminary cable meets 725.136(I), then I would think that my proposed arrangement would meet it as well. The only difference is conduit on the outside instead of cable armor.

Cheers, Wayne

 

[hbiss]

(I) Other Applications. For other applications, conductors
of Class 2 and Class 3 circuits shall be separated by at least
50 mm (2 in.) from conductors of any electric light, power,
Class 1 non–power-limited fire alarm or medium power
network-powered broadband communications circuits unless
one of the following conditions is met:

(1) Either (a) all of the electric light, power, Class 1, non–
power-limited fire alarm and medium-power networkpowered
broadband communications circuit conductors
or (b) all of the Class 2 and Class 3 circuit conductors
are in a raceway or in metal-sheathed, metal-clad, non–
metallic-sheathed, or Type UF cables.

After reading this indeed it seems you are correct.

-Hal