480V Control Circuit Wiring

[fifty60]

I have an LED light that accepts a 480V input, and via a mini-transformer steps this down to 7V to power an LED. The mini-transformer is part of the LED light itself. My connections to the light are 480V.

I know for power circuits above 120V the minimum wire gauge is 14AWG. I would not consider this a power circuit, but a control circuit. The 480V branch circuit is protected by a 4A breaker. Am I able to use 18AWG for this LED? Or, would the minimum be 14AWG since it is on a 480V circuit?

I am trying to see what range the input terminals take, but I cannot find it listed on the manufacturers website. It seems like it would take an executive order of some kind to actually talk to the manufacturer....so I am trying to approach the problem from NFPA 79 or UL 508A perspective...

 

[kwired]

Is the light for premises lighting or is it a component of an appliance or machinery?

If it is general premises lighting I think it needs to be 14 AWG minimum.

 

[augie47]

More than likely a UL508 question but it appears NEC 430.72 will allow a #18 if motors are involved and Art 725 will allow 18 fro Class 1 circuits..

 

[fifty60]

The light will be a pilot light on a piece of machinery. I have not problem using 14 or 12AWG on this, but I am not sure if the manufacturers terminals are sized for this gauge of wire...

 

[kwired]

The light will be a pilot light on a piece of machinery. I have not problem using 14 or 12AWG on this, but I am not sure if the manufacturers terminals are sized for this gauge of wire...

That sounds like a control circuit then instead of power/lighting circuit. 725 does apply to such circuits and you can run smaller then 14 AWG in many situations.

 

[fifty60]

Thank you for the assistance guys.

 

[Jraef]

That sounds like a control circuit then instead of power/lighting circuit. 725 does apply to such circuits and you can run smaller then 14 AWG in many situations.

Typical for things like that in MCCs or control panels is #16, partly because 18 and below requires fusing to be 7A max, yet a lot of full voltage control circuits are fused at 10A because that's what typical 600V pilot device and relay contacts are rated for (NEMA A600 = make 60, break 6, 10A continuous). I would imagine however that most pilot lights, including the type you described, are set up to accept #14, because regardless of what the NEC or UL requires, a lot of user specs call for #14 minimum. So if you make a pilot light that can't accept #14, there are a lot of industrial places where your product can't be used.

 

[kwired]

Typical for things like that in MCCs or control panels is #16, partly because 18 and below requires fusing to be 7A max, yet a lot of full voltage control circuits are fused at 10A because that's what typical 600V pilot device and relay contacts are rated for (NEMA A600 = make 60, break 6, 10A continuous). I would imagine however that most pilot lights, including the type you described, are set up to accept #14, because regardless of what the NEC or UL requires, a lot of user specs call for #14 minimum. So if you make a pilot light that can't accept #14, there are a lot of industrial places where your product can't be used.

Pigtail to the device? Some devices have leads instead of terminal screws/lugs.

 

[Jraef]

Pigtail to the device? Some devices have leads instead of terminal screws/lugs.

Yeah, that's true, but on those that I've used, like the old little Neon indicators that came with 20ga leads, they are not UL listed, they are UR, which means they can only be used in assemblies that will be UL listed and will require conditions of use. One of those condition, as I found out the hard way once, is that those little ones with 20ga leads required a 5A max fuse on the circuit. So to make them work, the lights often had to have their own separate 5A fused circuit, because any decent size starter coil would pop that fuse. Then if that 5A fuse did blow, ALL of the indicators would not light up, so you lost motor running indication for example. It made it too much of a PITA to use them on any panel that had motor controls in it.

 

[fifty60]

Extemely helpful insight, thank you. I am still waiting on information back from the manufacturer, though with these guys I bet the part will make it here first before I hear back from them...