Low & Line Voltage Same Conduit

[Alwayslearningelec]

In this scenario if wiring has to be in EMT how does one know of 120v and control wiring can be installed in same conduit?

The class rating of the control wiring? It says class 2! The insulation rating? Thanks

 

[kwired]

Class 2 and class 3 wiring (individual conductors or cables) plain and simple can not be in raceway with class 1 and/or power conductors.

You could have class 1 or power circuit in a chapter 3 cable method in same "chase" (which could be something also listed as a raceway such as EMT) as a class 2 or 3 wiring cable though.

 

[tank728]

You are talking about the lmrc-213 in your photo correct? If you look at the device the purple and grey wires land on the front, in free air of the lmrc. The lmrc mounts directly to a 1900 box for all line voltage splices.

 

[Alwayslearningelec]

You are talking about the lmrc-213 in your photo correct? If you look at the device the purple and grey wires land on the front, in free air of the lmrc. The lmrc mounts directly to a 1900 box for all line voltage splices.

I understand but the control wires(vio/gry) need to be run in EMT since it's exposed ceilings(spec). Can't be "free air".

 

[Alwayslearningelec]

Class 2 and class 3 wiring (individual conductors or cables) plain and simple can not be in raceway with class 1 and/or power conductors.

You could have class 1 or power circuit in a chapter 3 cable method in same "chase" (which could be something also listed as a raceway such as EMT) as a class 2 or 3 wiring cable though.

I don't follow your last paragraph? Where exactly in NEC is this detailed? Thanks.

 

[xformer]

I don't follow your last paragraph? Where exactly in NEC is this detailed? Thanks.

Article 725.136

 

[tank728]

I understand but the control wires(vio/gry) need to be run in EMT since it's exposed ceilings(spec). Can't be "free air".

Then you need to use the conduit adapter

Conduit Adapter for enhanced room controller | Interfaces and Accessories | Digital Lighting Management | Lighting Controls and Systems

LMRC-210 Series Digital Room Controllers include one, two or three relay(s) to switch a total of 15 or 20 amps, a highefficiency switching power supply and one 0-10 volt output per relay for control of dimmable loads including electronic ballasts (Advance Mark 7, or equivalent). They are the...

www.legrand.us

 

[Alwayslearningelec]

Then you need to use the conduit adapter

Conduit Adapter for enhanced room controller | Interfaces and Accessories | Digital Lighting Management | Lighting Controls and Systems

LMRC-210 Series Digital Room Controllers include one, two or three relay(s) to switch a total of 15 or 20 amps, a highefficiency switching power supply and one 0-10 volt output per relay for control of dimmable loads including electronic ballasts (Advance Mark 7, or equivalent). They are the...

www.legrand.us

I plan on them going into a 4" box so a standard connector.

 

[kwired]

Are those 0-10V control wires intended to be class 2 only or can they be class 1 conductors? If they can be class 1 conductors they can be in raceway with power conductors that they are associated with.

Just because something is "low voltage" doesn't automatically make it class 2. Other components in the circuit can dictate whether or not they must be class 2.

 

[Alwayslearningelec]

Are those 0-10V control wires intended to be class 2 only or can they be class 1 conductors? If they can be class 1 conductors they can be in raceway with power conductors that they are associated with.

Just because something is "low voltage" doesn't automatically make it class 2. Other components in the circuit can dictate whether or not they must be class 2.

it’s clearly says class 2 on the drawing i posted.

 

[tank728]

But it does not say class 2 only

 

[don_resqcapt19]

But it does not say class 2 only

You have to look at the marking on the power source....It may say Class 2 or it may not, some even say Class 1 or Class 2. Even if it does say Class 2, you can apply Exception #2 to 725.130(A) and install the controls with the power as long as you use Class 1 wiring methods for the controls.

 

[kwired]

You have to look at the marking on the power source....It may say Class 2 or it may not, some even say Class 1 or Class 2. Even if it does say Class 2, you can apply Exception #2 to 725.130(A) and install the controls with the power as long as you use Class 1 wiring methods for the controls.

And all other components on same circuit must be suitable for class 1 as well.

Example - 24V HVAC controls. You possibly could run those with the power supply circuit on the way to a thermostat, but that thermostat could no longer be a typical class 2 rated thermostat, it basically would need to be a line voltage rated thermostat, and your wiring method needs to remain a class 1 method the entire length of the circuit.

 

[don_resqcapt19]

And all other components on same circuit must be suitable for class 1 as well.

Example - 24V HVAC controls. You possibly could run those with the power supply circuit on the way to a thermostat, but that thermostat could no longer be a typical class 2 rated thermostat, it basically would need to be a line voltage rated thermostat, and your wiring method needs to remain a class 1 method the entire length of the circuit.

The code stops short of saying that. There are differences of opinion on that issue between the various AHJs. Some enforce it as you have stated and others only require that the wiring method, and not the associated equipment, be suitable for Class 1 installations.

 

[GoldDigger]

The code stops short of saying that. There are differences of opinion on that issue between the various AHJs. Some enforce it as you have stated and others only require that the wiring method, and not the associated equipment, be suitable for Class 1 installations.

IMHO it seems simple that if the equipment requires Class 2 input and you have removed the Class 2 rating of the power source you are violating the listed operation of that equipment.
The problem is that even though the source is internally still Class 2, the associated wiring may, in case of failure, expose the equipment to more than Class 2 applied power, causing an unsafe condition.

 

[don_resqcapt19]

IMHO it seems simple that if the equipment requires Class 2 input and you have removed the Class 2 rating of the power source you are violating the listed operation of that equipment.
The problem is that even though the source is internally still Class 2, the associated wiring may, in case of failure, expose the equipment to more than Class 2 applied power, causing an unsafe condition.

The exception is based on the fact that once you use Class 1 wiring methods for the reclassified circuits, there is a very reduced chance of putting line voltage on the control circuits creating a hazard. The CMP sees that as an acceptable risk.

It appears that the 2023 code will just have a blanket provision to mix Class 2 wiring with line voltage or Class 1 circuits anytime you use Chapter 3 wiring methods for the Class 2 circuits. The exception will go away.