UL508A and NFPA79 Wire Colors

[JacL]

Hello,

I am currently designing/building a protection and control panel for generator and switchgear control.
The main incoming is 120Vac. This feeds a couple of heaters, and a UPS.
I have a few incoming CT and PT circuits for measurement and protection purposes.
The UPS supplies 24Vdc to the majority of the control panel.
On the 24Vdc system I am feeding a couple of 24Vdc gate actuators external to the panel, powering a few control devices/IO, and powering a PLC with digital/analog IO cards.

Looking through UL508A I do not see wire colors specified anywhere for power or control circuits except for in the "Industrial Machinery" section.
The standard defines these panels as controlling...

65.1 These requirements cover industrial control panels for industrial machinery (NFPA 79, Electrical
Standard for Industrial Machinery). The following types of machines are identified as industrial machinery:
a) Metalworking machine tools, including machines that cut or form metal;
b) Plastics machinery, including injection molding, extrusion, blow molding, specialized
processing, thermoset molding, and size reduction machines;
c) Wood machinery, including woodworking, laminating, and sawmill machines;
d) Assembly machines;
e) Material handling machines, including industrial robots and transfer machines; and
f) Inspection and testing machines, including coordinate measuring and in-process gauging
machines.

Considering I have some flow/level sensors in my system "inspection and testing machines" may apply, however it's pretty vague definition.

I have not found a UL508a panel guide or forum post discussing this possible exemption to the outlined wire color code that most people seem to follow.
I am wondering if I am missing something obvious here, or if there is a good chance I can move forward with this build using any wire colors while still complying with the standard.
If this is not the case it looks like my panel may require 99% orange and white/orange wire due to the CT/PT circuits, and most of my panel being 24Vdc downstream of a UPS system.

Any input would be appreciated.

 

[petersonra]

If it is not an industrial machine you do not have to follow the color code found in the industrial machine section. There are some colors specified elsewhere that you still have to follow. The problem is that it is often expected that this color code be followed even if it's not required.

I don't think your application is an industrial machine so I don't see why you would have to follow that color code. But unless there's some really good reason not to I would do so.

 

[JacL]

Thanks for the quick response Bob.

I have plenty of orange however the problem I am running into is that I haven't been able to source the white/orange with a reasonable lead time compared to other colors which are typically stocked in my area, and I have multiconductor instrumentation cables that certainly don't follow the orange and white/orange coloring scheme that I would require.

I see that 66.5.1.1 also offers another possible exemption if you explicitly state the differences on a label and on the drawings.
Have you ever seen or heard of this being used with success?

 

[SSDriver]

I purchase MTW wire from automationdirect.com all the time. They have white/orange in stock and free 2 day shipping if you spend over $49.

https://www.automationdirect.com/adc/shopping/catalog/wiring_solutions/electrical_hook-up_-z-_building_wire/insulation_type_-_mtw#Conductor_Insulation_Color_ms=%22White%20with%20Orange%20Stripe%22&start=0

 

[petersonra]

Thanks for the quick response Bob.

I have plenty of orange however the problem I am running into is that I haven't been able to source the white/orange with a reasonable lead time compared to other colors which are typically stocked in my area, and I have multiconductor instrumentation cables that certainly don't follow the orange and white/orange coloring scheme that I would require.

I see that 66.5.1.1 also offers another possible exemption if you explicitly state the differences on a label and on the drawings.
Have you ever seen or heard of this being used with success?

I'm not sure you required to follow the color coding standard for multiconductor cable. It's only for single conductors I think.

 

[Jraef]

Orange would be for FOREIGN voltage sources IN THE PANEL, not exiting it to devices. If your 24VDC is sourced from your panel, those are not foreign circuits.

All you need is red for 120V hot, white for neutral, blue for DC and black for the CT secondary circuits.

 

[petersonra]

Orange would be for FOREIGN voltage sources IN THE PANEL, not exiting it to devices. If your 24VDC is sourced from your panel, those are not foreign circuits.

All you need is red for 120V hot, white for neutral, blue for DC and black for the CT secondary circuits.

You should probably look up the actual definition of what orange wire means it doesn't mean foreign circuits. It means circuits that are not disconnected when the panel disconnect is open. so anything powered by a UPS from inside the panel needs to be orange unless a disconnect removes power from the secondary side of the UPS

 

[JacL]

The UPS and Battery bank both have circuit breakers immediately downstream.
That being said, what is classified as the main disconnect?

Would both of those circuit breakers be considered the "main disconnects" for the 24Vdc system or would only the circuit breaker with the 120VAC incoming feeding the UPS be considered the "main disconnect" as it is the true main disconnect to incoming power of the panel?

 

[petersonra]

The UPS and Battery bank both have circuit breakers immediately downstream.
That being said, what is classified as the main disconnect?

Would both of those circuit breakers be considered the "main disconnects" for the 24Vdc system or would only the circuit breaker with the 120VAC incoming feeding the UPS be considered the "main disconnect" as it is the true main disconnect to incoming power of the panel?

Ul508a does not say anything about a main disconnect. It talks about a panel disconnecting means. I think you need to look in the standard and see whether these circuit breakers qualify. I am not where I have convenient access to the standard but I'm pretty sure that a circuit breaker on the inside of the panel would not qualify unless it can be operated from the outside of the panel. The other thing is you still have live power in there up to the circuit breaker.

 

[petersonra]

Interesting that the sign phrasing using the term "main disconnect".

 

[JacL]

The other thing is you still have live power in there up to the circuit breaker.

Perhaps... but I believe that the orange color coding only applies to control circuits. As my external actuators are powered off of the 24Vdc system it would also contain some 24Vdc power circuits so these would be black and white.

Regarding your last reply, it seems to me like the circuit breakers downstream of the UPS are not considered "main disconnects".

I have found this standard quite disappointing when it comes to clearly defining certain critical key terms such as this.

Similarly when it comes to defining what is a control vs. power circuit.
For example, what is a circuit classified as when it is supplying power to a device such as a PLC?
The PLC has a power supply which would indicate to me a power circuit since it would "carry the main power circuit" and control circuits are defined as not doing this.
Tapping off of this circuit you could power the I/O cards which to me would indicate a control circuit since it is "directing the performance of a controller. and which does not carry the main power circuit".
Is this circuit a power circuit, a control circuit, a mixture?

Perhaps I am not fully understanding some of these classifications, but to me in places this standard seems either very poorly written or vague on purpose.

 

[petersonra]

If you look carefully I think you will find that pretty much any circuit that doesn't leave the control panel is a control circuit by UL standards.

I also think you can look at the standard where it talks about lower energy circuits. They're pretty much talking about class 1 circuits and the standard is pretty clear that those are controlled circuits even if they fire up solenoid valves or other external loads.

 

[Russs57]

I know nothing about the standards you list, or code in general.

I will say that all of the factory wiring (in most of the generator switchgear and ATS's I have seen) are grey #14 type SIS with labels.

 

[petersonra]

I know nothing about the standards you list, or code in general.

I will say that all of the factory wiring (in most of the generator switchgear and ATS's I have seen) are grey #14 type SIS with labels.

Different standards. UL mcc standards for instance allow grounded control circuits within MCC to be red

 

[RumRunner]

If you look carefully I think you will find that pretty much any circuit that doesn't leave the control panel is a control circuit by UL standards.

I also think you can look at the standard where it talks about lower energy circuits. They're pretty much talking about class 1 circuits and the standard is pretty clear that those are controlled circuits even if they fire up solenoid valves or other external loads.

So, what's your position?

Where do you stand in terms of technological know how that you endorse regarding proper use of wire colors.

On your first paragraph you sound like you are delivering gospel that --to comply with UL Standards it must be: "circuit that doesn't leave the control panel is a control circuit."

It is loud and clear--ergo-- the UL Standard is satisfied.

However, on your second paragraph-- you are saying that external loads like solenoids are also controlled circuits.
But these (solenoids) are external loads that are definitely OUTSIDE the control panel.

This puts your God’s Gospel null and void –literally.

Tell us which one to pursue-- or you are just as confused as those UL guys. . . .chasing their own tails.
This dilly dallying, and flip flopping are not productive.

I listen to everyone's idea and I believe in yours too.

If you think that your idea is what I can recite up on the platform and tell people "this is the way it should be" because that is what you told us.

You should stand behind it too.

 

[petersonra]

Some of the UL requirements are not obvious and some have what amounts to exceptions. I often have to look up things that I do not come across that often even though I have been designing ul listed panels for the better part of 30 years.

 

[RumRunner]

When I worked in food processing plant years ago, the company imported a bottling machine that was built in Austria.

This was a machine that applies labels to the their product. The machine was ordered before I got on board.. . . I was the guy to install it, wire it, and set it up for production.
It applies labels at 875 bottles per minute.

As soon as it arrived at the receiving dock I just looked at it-- briefly, checked the crates and signed off the invoice.

To my surprise . . .after I asked the electrician to open the control cabinet, the wiring inside were all done with white wires.

So much for machine made in Austria.

Long story short--AHJ did not require a total rewire when he saw the extent that would be needed to do a complete rewire.

Identifying the wires wasn't a problem because all PLC input/output were permanently tagged as shown on the print.

AHJ did require to have the HOT and NEUTRAL control wires identified and replaced with RED and WHITE respectively.
The ground wire which was yellow with green trace also stayed where it was.

The inside of the cabinet looks nice and clean with all white wires-- and wire markers were clearly visible along with gray contrast offered by the inside paint of the cabinet.

Maybe we should do the same thing like the Austrians do