UL508A vs NEC Power Circuit Wire Colors

[DAB41162]

Hello,

I'm building an industrial control panel being fed by a 208V single phase source ( L1, L2, N, Gnd). It is part of an integrated measurement system that will need a UL label.

I know that UL508A says:

"66.5.3 The following color coding shall be used throughout the panel:
a) Black – all ungrounded power circuit conductors regardless of voltage;..."

However, NEC code says L1 be black and L2 be red. My thought is that a facility electrician would recognize the black and red wires, inside the panel, as power wires for L1/L2.

Thoughts?

 

[tom baker]

UL 508 says shall.
A label could be used with colors and voltages
What about red with a black stripe?

 

[DAB41162]

UL 508 says shall.
A label could be used with colors and voltages
What about red with a black stripe?

Thank you,

That can be done.

What would be the relationship between 508 and 508A? I'm sure I'll be asked if anything but black is used.

 

[petersonra]

Hello,

I'm building an industrial control panel being fed by a 208V single phase source ( L1, L2, N, Gnd). It is part of an integrated measurement system that will need a UL label.

I know that UL508A says:

"66.5.3 The following color coding shall be used throughout the panel:
a) Black – all ungrounded power circuit conductors regardless of voltage;..."

However, NEC code says L1 be black and L2 be red. My thought is that a facility electrician would recognize the black and red wires, inside the panel, as power wires for L1/L2.

Thoughts?

The NEC does not specify such a color code.

I would caution you that paragraph 66 in UL508a only applies to control panels for industrial machines.

Look closely at an AB MCC some time. All the grounded conductors in the control circuits are red.

 

[petersonra]

Thank you,

That can be done.

What would be the relationship between 508 and 508A? I'm sure I'll be asked if anything but black is used.

He probably meant UL508a. UL508 is a standard for industrial control equipment. It confuses a lot of people due to the similarity in designations.

 

[tom baker]

Thank you,

That can be done.

What would be the relationship between 508 and 508A? I'm sure I'll be asked if anything but black is used.

Oops it’s early here, I meaner UL508A

 

[tom baker]

The NEC does not specify such a color code.

I would caution you that paragraph 66 in UL508a only applies to control panels for industrial machines

Great point. The NEC with some exceptions does not specify a color code. They assume your qualified electricians have a voltmeter.

 

[DAB41162]

The NEC does not specify such a color code.

I would caution you that paragraph 66 in UL508a only applies to control panels for industrial machines.

Okay, my experience has three phase 240V is black, red, and blue. This isn't specified by NEC?

The reason I believe 508A applies is that the panel feeds power to machinery and controls its operation as well as its safety interlocks.

Thank you...

 

[LarryFine]

This isn't specified by NEC?

Nope. Only green, white, gray, and orange.

If it's not green, white, or gray, presume it's hot.

 

[DAB41162]

Nope. Only green, white, gray, and orange.

If it's not green, white, or gray, presume it's hot.

Thank you...

 

[petersonra]

Okay, my experience has three phase 240V is black, red, and blue. This isn't specified by NEC?

No. It might be a convention used in your plant or a practice that is common in your area but is not a code requirement.

The reason I believe 508A applies is that the panel feeds power to machinery and controls its operation as well as its safety interlocks.

UL508a is a standard that UL publishes. It is also a program where UL allows control panels made by some manufacturers to be listed by UL as long as they meet the various requirements. Unless UL blesses your company though, you cannot build a UL listed control panel, nor apply the UL label.

There is no code requirement that an industrial control panel be listed, although it might be required by local authorities or OSHA.

 

[DAB41162]

No. It might be a convention used in your plant or a practice that is common in your area but is not a code requirement.


UL508a is a standard that UL publishes. It is also a program where UL allows control panels made by some manufacturers to be listed by UL as long as they meet the various requirements. Unless UL blesses your company though, you cannot build a UL listed control panel, nor apply the UL label.

There is no code requirement that an industrial control panel be listed, although it might be required by local authorities or OSHA.

Okay. I'm not looking to have the control panel listed, rather, build it to the UL508A standard in hopes of facilitating a UL inspection.

BTW, the planet is earth, and the practice is electrician. Here, it's black, red, blue for 240V, and brown, orange, yellow, for 480V, 3 phase.

Thank you...

 

[petersonra]

Okay. I'm not looking to have the control panel listed, rather, build it to the UL508A standard in hopes of facilitating a UL inspection.

BTW, the planet is earth, and the practice is electrician. Here, it's black, red, blue for 240V, and brown, orange, yellow, for 480V, 3 phase.

Thank you...

You would better off just having a panel shop authorized to apply the UL label do so. Field evaluations are insanely expensive.

It would likely cost less to have such a shop build it for you.

 

[LarryFine]

BTW, the planet is earth, and the practice is electrician. Here, it's black, red, blue for 240V, and brown, orange, yellow, for 480V, 3 phase.

Those are certainly the traditional colors we use, but they are not code mandated.

We're not giving you a hard time, just answering you as accurately as we can.

 

[DAB41162]

You would better off just having a panel shop authorized to apply the UL label do so. Field evaluations are insanely expensive.

It would likely cost less to have such a shop build it for you.

Take care

 

[kwired]

BTW, the planet is earth, and the practice is electrician. Here, it's black, red, blue for 240V, and brown, orange, yellow, for 480V, 3 phase.

Thank you...

As already mentioned, NEC is silent about specific colors other than green, green with yellow stripe, white, gray, and orange - but only for high leg delta.

NEC does require identification of system and phase when multiple systems exist but doesn't specify how to do so. The color scheme you mentioned is pretty commonly used though, and possibly is the rule in some jurisdictions.

 

[Jraef]

Look closely at an AB MCC some time. All the grounded conductors in the control circuits are red.

UL845 for MCCs does not call out any wire colors. But most manufacturers follow the original JIC standards, which were adopted by NFPA 79, the standard for industrial machinery control systems and since MCCs are ostensibly only going to be used on industrial machinery, it makes sense.

NFPA 79 says the following:

14.2.3 Identification of the Grounded Circuit Conductor.
14.2.3.1 Where an ac circuit includes a grounded conductor, this conductor shall be WHITE, GRAY, or three continuous
WHITE stripes on other than GREEN, BLUE, ORANGE, or YELLOW insulation along its entire length.

Then later:

14.2.4.3 The use of other colors for the purpose of identification shall be as follows:
(1) BLACK for ungrounded line, load, and control conductors at line voltage
(2) RED for ungrounded ac control conductors at less than line voltage
(3) BLUE for ungrounded dc control conductors