0-10v dimming again

[jap]

LED Highbay has 2 cords coming out of the housing with a hook mount.

One 3c 14ga cord is for the 120v Power, One 2c 16ga cord is for the 0-10v dimming.

All will be in a warehouse, all surface mount exposed conduit installation.

The plan is to hang the fixtures on an eyebolt and piping to each fixture and setting a box next to each and bringing both cords into a common 4sq box from the switch location.

Here's the delima.

Can the 120v and 0-10v wiring be installed together in one conduit from the switch location to the fixtures if all Thhn wiring is used ?

or

Do (2) separate conduits need to be installed from the switch location to (2) separate boxes next to the fixture to keep the 120v and 0-10v cords and wiring completely separate?

JAP>

 

[augie47]

IMO, you have a choice of installing them as Class 1 circuits and follow 725.48 or Class 2 circuits and follow 725.136 (Note than in 725.136 (D) your power conductors are limited to 150 volts)

 

[jap]

IMO, you have a choice of installing them as Class 1 circuits and follow 725.48 or Class 2 circuits and follow 725.136 (Note than in 725.136 (D) your power conductors are limited to 150 volts)

It would seem per 725.48 A if we wire it as a Class 1 circuit with all THHN 600v rated wiring, then they could share the same raceway and only 1 conduit would need to be run from the switch location to each fixture location.

Am I wrong in assuming such?

JAP>

 

[RunningSparky]

It would seem per 725.48 A if we wire it as a Class 1 circuit with all THHN 600v rated wiring, then they could share the same raceway and only 1 conduit would need to be run from the switch location to each fixture location.

Am I wrong in assuming such?

JAP>

This is how we have always done it. One conduit, 600V wire

 

[hbiss]

Here we go again. If you could do that why couldn't you just use 4 wire MC for regular fixtures that use 0-10v dimming? Why do you think a manufacturer went through the trouble of getting listed and manufacturing Luminary MC cable?

This question comes up every few weeks with any number of opinions which means there is no clear understanding. Somebody (Code making panel or Mike) needs to clearly explain what you can and cannot do when it comes to 0-10v dimmer wiring.

-Hal

 

[augie47]

Here we go again. If you could do that why couldn't you just use 4 wire MC for regular fixtures that use 0-10v dimming? Why do you think a manufacturer went through the trouble of getting listed and manufacturing Luminary MC cable?

This question comes up every few weeks with any number of opinions which means there is no clear understanding. Somebody (Code making panel or Mike) needs to clearly explain what you can and cannot do when it comes to 0-10v dimmer wiring.

-Hal

I will readily admit every time I think I have an understanding I read more and re-confuse myself.
My original answer was biased based on the fact that the fixtures already had the two cords.
There are some details involved in the install where I do have questions:
(a) If we incorporate the two cables supplied with the fixture would one not need to
address 410.62(C) in regard to the power wiring and install a cord and plug ?
(this would seem to make the Luminary MC a better choice)
(b) Assuming we use the Luminary MC Cable and keep the dimming circuity Class 2,
would we not have to maintain the 1/4" separation once we entered a j box and
keep our Class 2 wiring separate from the power supply conduits ahead of the MC ?
(c) If we use the Class 2 wiring methods even with the Luminary MC would our power
voltage not be limited to 150 volts per 725.136(D) ?

 

[wwhitney]

So let's say for the moment that pulling individual 0-10v dimming conductors in the same raceway as the power conductors is not OK, but the MC Luminary cable is OK because the 0-10v dimming conductors are confined within an overall jacket within the MC Luminary cable.

That makes we wonder whether it would be OK to pull 16/2 FPLR cable for the 0-10v dimming conductors in the same raceway as the power conductors? The FPLR has an overall jacket and a 300V rating (at least some do, I'm not so familiar with this cable type). [I would ask the same question about 14/2 NM cable, but that is likely impractical due to the large diameter, which the unneeded grounding conductor contributes to.]

Cheers, Wayne

 

[hbiss]

I will readily admit every time I think I have an understanding I read more and re-confuse myself.
There are some details involved in the install where I do have questions:

(a) If we incorporate the two cables supplied with the fixture would one not need to
address 410.62(C) in regard to the power wiring and install a cord and plug ?

Section 410.62(C)(1)(2)c permits a listed manufactured
wiring system connector that is part of a fabricated assembly
to supply electric-discharge luminaires in place of a
grounding-type attachment plug.

It would seem to me then that you are still required to use a plug and receptacle on the line voltage cable. I don't think a strain relief connector off a J box meets the requirements of a fabricated assembly, but I could be wrong.


(b) Assuming we use the Luminary MC Cable and keep the dimming circuity Class 2,
would we not have to maintain the 1/4" separation once we entered a j box and
keep our Class 2 wiring separate from the power supply conduits ahead of the MC ?

I would think so. Somebody posted information about fish paper dividers a short while back.

(c) If we use the Class 2 wiring methods even with the Luminary MC would our power
voltage not be limited to 150 volts per 725.136(D) ?

AFC says their luminary cable is rated for 600V.

Keep in mind here that, depending on the installation (like if these were hanging from trusses) you could just ty-rap some CL2 cable along with the conduit or MC and save some money.

So let's say for the moment that pulling individual 0-10v dimming conductors in the same raceway as the power conductors is not OK, but the MC Luminary cable is OK because the 0-10v dimming conductors are confined within an overall jacket within the MC Luminary cable.

That makes we wonder whether it would be OK to pull 16/2 FPLR cable for the 0-10v dimming conductors in the same raceway as the power conductors? The FPLR has an overall jacket and a 300V rating (at least some do, I'm not so familiar with this cable type). [I would ask the same question about 14/2 NM cable, but that is likely impractical due to the large diameter, which the unneeded grounding conductor contributes to.]

Cheers, Wayne

The CL2 has to be a listed 600V cable assembly, not individual 600V conductors like THHN.

I mentioned NM before as an example but agree it's impractical for the reasons you mention. I did suggest at one time a 600V 18/2 type TC (tray cable).

-Hal

 

[jap]

Keep in mind here that, depending on the installation (like if these were hanging from trusses) you could just ty-rap some CL2 cable along with the conduit or MC and save some money.

-Hal

That's exactly what we did in the offices.
Just seems odd to have to do that in the warehouse where everything is exposed.
Would rather incorporate in the same conduit but can't find a clear statement that indicates that's not a code violation.

Jap>

 

[wwhitney]

The CL2 has to be a listed 600V cable assembly, not individual 600V conductors like THHN.

I'm sorry, where does the 600V requirement come from? The only hits on 600V I find in Article 725 are for Class 1 circuits.

I mentioned NM before as an example but agree it's impractical for the reasons you mention. I did suggest at one time a 600V 18/2 type TC (tray cable).

Nice idea on the TC cable. I'm still wondering if the FPLR would be more readily available and would also work.

And I guess if conduit fill permits, NM cable could be used for the power conductors, and individual conductors for the 0-10V dimming conductors. Round 12/3 (is it still available?) has a smaller diameter than 12/2.

Cheers, Wayne

 

[augie47]

(
...........................................................................................
(c) If we use the Class 2 wiring methods even with the Luminary MC would our power
voltage not be limited to 150 volts per 725.136(D) ?

AFC says their luminary cable is rated for 600V.

Keep in mind here that, depending on the installation (like if these were hanging from trusses) you could just ty-rap some CL2 cable along with the conduit or MC and save some money.



The CL2 has to be a listed 600V cable assembly, not individual 600V conductors like THHN.

I mentioned NM before as an example but agree it's impractical for the reasons you mention. I did suggest at one time a 600V 18/2 type TC (tray cable).

-Hal

Not challenging but attempting to enlighten myself...
I read 725.136(D)(2) to mean the "circuit conductors including luminaire power.... apparently you read it to be the control circuit conductors only....

 

[hbiss]

I'm sorry, where does the 600V requirement come from? The only hits on 600V I find in Article 725 are for Class 1 circuits.

I assume the 600V requirement comes from the 600V listing of the THHN used for the power conductors.

Not challenging but attempting to enlighten myself...
I read 725.136(D)(2) to mean the "circuit conductors including luminaire power.... apparently you read it to be the control circuit conductors only....

What I meant was the CL2 cable has to be listed for the same voltage as the luminaire power (or circuit) conductor listing- in this case THHN/600V.

However then there is 725.136(D)(2)(a) that allows CL3 cable conductors if used with a CL2 circuit to be installed with a minimum of .25 inch separation from power conductors 150V to ground or less in a J box. So I take that to mean that if you run a separate CL3 cable around to your luminaires you can bring that into your J boxes as long as you maintain the .25" separation.

725.136(D) Associated Systems Within Enclosures.

Class 2 and Class 3 circuit conductors in compartments, enclosures, device boxes, outlet boxes, or similar fittings shall be permitted to be installed with electric light, power, Class 1, non–powerlimited fire alarm, and medium-power network-powered broadband communications circuits where they are introduced solely to connect the equipment connected to Class 2 and Class 3 circuits, and where (1) or (2) applies:

(1) The electric light, power, Class 1, non–power-limited fire alarm, and medium-power network-powered broadband communications circuit conductors are routed to maintain a minimum of 6 mm (0.25 in.) separation from the conductors and cables of Class 2 and Class 3 circuits.

(2) The circuit conductors operate at 150 volts or less to ground and also comply with one of the following:

a. The Class 2 and Class 3 circuits are installed using Type CL3, CL3R, or CL3P or permitted substitute cables, provided these Class 3 cable conductors extending beyond the jacket are separated by a minimum of 6 mm (0.25 in.) or by a nonconductive sleeve or nonconductive barrier from all other conductors.

b. The Class 2 and Class 3 circuit conductors are installed as a Class 1 circuit in accordance with
725.41.

-Hal

 

[david]

Here's the delima.

Can the 120v and 0-10v wiring be installed together in one conduit from the switch location to the fixtures if all Thhn wiring is used ?

or

Do (2) separate conduits need to be installed from the switch location to (2) separate boxes next to the fixture to keep the 120v and 0-10v cords and wiring completely separate?

JAP>

Be careful a lot of times dimmers are ganged and the class two circuits can all share together the same conduit .

Make sure when using conduit and pull and junction boxes and mixing the power conductors with re-classified class 2 circuits the power conductors are functionally associated with all the class 2 circuits in the same conduit.

(1) In a Cable, Enclosure, or Raceway. Class 1 circuits and power-supply circuits shall be permitted to occupy the same cable, enclosure, or raceway only where the equipment powered is functionally associated.

 

[wwhitney]

I assume the 600V requirement comes from the 600V listing of the THHN used for the power conductors.

But I don't see any requirement that the CL2 cable insulation rating would have to match the insulation rating of the power conductors. So I don't see any problem using FPLR 300V cable for a CL2 circuit within a conduit with power conductors operating at under 300V, under 725.136(I)(1), the same section that allows the use of MC Luminary cable.

Am I missing something?

Cheers, Wayne

 

[hbiss]

Make sure when using conduit and pull and junction boxes and mixing the power conductors with re-classified class 2 circuits the power conductors are functionally associated with all the class 2 circuits in the same conduit.

(1) In a Cable, Enclosure, or Raceway. Class 1 circuits and power-supply circuits shall be permitted to occupy the same cable, enclosure, or raceway only where the equipment powered is functionally associated.

I give up. Read 725.136. There is NOTHING about being able to reclassify CL2 to class 1.

Like I said above, this is an subject needing immediate clarification from the Code making panel.

-Hal

 

[augie47]

I give up. Read 725.136. There is NOTHING about being able to reclassify CL2 to class 1.

Like I said above, this is an subject needing immediate clarification from the Code making panel.

-Hal

725.130(A) Exception 2

 

[hbiss]

Ok, let's chase that rabbit hole.

725.130 Wiring Methods and Materials on
Load Side of the Class 2 or Class 3 Power
Source
Class 2 and Class 3 circuits on the load side of the power
source shall be permitted to be installed using wiring methods and materials in accordance with either 725.130(A) or (B).
(A) Class 1 Wiring Methods and Materials. Installation
shall be in accordance with 725.46.

Exception No. 2: Class 2 and Class 3 circuits shall be permitted
to be reclassified and installed as Class 1 circuits if
the Class 2 and Class 3 markings required in 725.124 are
eliminated and the entire circuit is installed using the wiring
methods and materials in accordance with Part II, Class 1
circuits.

725.49 Class 1 Circuit Conductors
.
(B) Insulation. Insulation on conductors shall be rated for
600 volts. Conductors larger than 16 AWG shall comply
with Article 310. Conductors in sizes 18 AWG and 16 AWG
shall be Type FFH-2, KF-2, KFF-2, PAF, PAFF, PF, PFF,
PGF, PGFF, PTF, PTFF, RFH-2, RFHH-2, RFHH-3, SF-2,
SFF-2, TF, TFF, TFFN, TFN, ZF, or ZFF. Conductors with
other types and thicknesses of insulation shall be permitted
if listed for Class 1 circuit use.

725.48 Conductors of Different Circuits in the
Same Cable, Cable Tray, Enclosure, or
Raceway
Class 1 circuits shall be permitted to be installed with other
circuits as specified in 725.48(A) and (B).

(B) Class 1 Circuits with Power-Supply Circuits. Class 1
circuits shall be permitted to be installed with power-supply
conductors as specified in 725.48(B)(1) through (B)(4).
(1) In a Cable, Enclosure, or Raceway. Class 1 circuits
and power-supply circuits shall be permitted to occupy the
same cable, enclosure, or raceway only where the equipment
powered is functionally associated.

This is where we need to apply some thinking, which really shouldn't be necessary if 725 were written clearly. We know that there is a luminary cable available with power and LV under one sheath. The manufacturer (AFC) spent a lot of money having this cable listed. Why would they do that if it were permissible to follow the Articles above and just use an off the shelf 4 conductor cable?

The answer is in the last sentence of 725.48(B)(1):

"Class 1 circuits and power-supply circuits shall be permitted to occupy the same cable, enclosure, or raceway only where the equipment powered is functionally associated."

As I remember, the phrase "functionally associated" is very strictly interpreted by the Code. There are rare instances where you can use it to reclassify a circuit. The NEC defines it to mean necessary for the operation of the equipment. One would think that you could run LV conductors to a condensing unit with the power if necessary. No, because the condensing unit doesn't need the thermostat in order to operate.

So, in our instance, can the luminaire operate without the LV dimmer? Yes it could. So dollars to donuts the NEC shot down allowing the 0-10V LV to be reclassified and be run with the power conductors because they didn't consider it functionally associated with the luminaires operation.

-Hal

 

[hbiss]

The next question is how are we supposed to know this. They really need to blow up 725 and re-write it. But there should be wiring requirements included with the manufacturers installation instructions that show how the LV and line voltage need to be run. But getting some Chinese company on board with that could be a problem.

I understand the frustration.

-Hal

 

[ActionDave]

......They really need to blow up 725 and re-write it.
-Hal

All I get is a headache when I look art. 725, I don't even try to read it.

 

[david]

Ok, let's chase that rabbit hole.



[

Class 1 circuits shall be permitted to be installed with other
circuits as specified in 725.48(A) and (B).



The answer is in the last sentence of 725.48(B)(1):

"Class 1 circuits and power-supply circuits shall be permitted to occupy the same cable, enclosure, or raceway only where the equipment powered is functionally associated."

As I remember, the phrase "functionally associated" is very strictly interpreted by the Code. There are rare instances where you can use it to reclassify a circuit. The NEC defines it to mean necessary for the operation of the equipment. One would think that you could run LV conductors to a condensing unit with the power if necessary. No, because the condensing unit doesn't need the thermostat in order to operate.

So, in our instance, can the luminaire operate without the LV dimmer? Yes it could. So dollars to donuts the NEC shot down allowing the 0-10V LV to be reclassified and be run with the power conductors because they didn't consider it functionally associated with the luminaires operation.

-Hal

You are not using the term to reclassify the circuit.

You are deciding to mix the low voltage circuits in the same race way with power conductors only where the power and low voltage conductors are functionally associated.

Nothing says you have to mix them in the same race way, though there would be little advantage to reclassifying the circuits if it were not your intention to mix the two together.
Other than you would no longer have to worry about separation say in a common switch box.

By the way is it not the intention of the manufactured cable you refer to, the circuits in the cable are functionally associated and are mixed in the same cable?

Perhaps i am missing something