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Old April 1st, 2020, 08:57 AM   #16
Timeismoney08
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Quote:
Originally Posted by jraef View Post
If discussing PLCs and such, we are always discussing industrial applications.


The Black/Red on 240V circuits is applicable to residential wiring. It has no meaning or validity in industrial systems. Black/Red for 240V single phase systems would be confusing and potentially dangerous for industrial systems.



In control panels, black = Line Power, red = AC control power, white = Neutral, blue = DC control power, yellow = Foreign source control power that is not disconnected by the main disconnect. These standards go back to the original JIC (Joint Industrial Council) standards from around WWII that eventually became absorbed by NFPA 79 for industrial machinery electrical systems. The standards were established to help prevent accidents when workers moved between facilities that might have had different standards. So when an industrial electrician opens a panel to try to troubleshoot a problem, he knows what he is looking at without needing a color chart.

So for a 480v fed system that steps down to 240V, you would use Red (120V), Red (120V), White (N)?

I've just never seen it done that way, but that's how I interpret the standards when I read it.
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Old April 1st, 2020, 09:46 AM   #17
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Quote:
Originally Posted by Timeismoney08 View Post
So for a 480v fed system that steps down to 240V, you would use Red (120V), Red (120V), White (N)?

I've just never seen it done that way, but that's how I interpret the standards when I read it.
No, your secondaries would be black line power.
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Old April 1st, 2020, 09:51 AM   #18
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Originally Posted by Maxkling View Post
No, your secondaries would be black line power.
I disagree. If 480V is present then it is line (black). The 240V wiring would both be red.

Use wire numbers on everything.
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Old April 1st, 2020, 11:51 AM   #19
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Quote:
Originally posted by Timeismoney08:

So for a 480v fed system that steps down to 240V, you would use Red (120V), Red (120V), White (N)?
What you are referring to here is a 480/240 single phase transformer that you are center grounding the secondary to get two separate 120VAC feeds. Do I have that right?

I don't want to say this isn't done but I think it is somewhat uncommon in industrial machinery. I have seen a case where this wiring was done but only one leg was used for the 120VAC feed to the cabinet. I think that is what is creating a little bit of confusion.

You need to be careful with this one. It isn't uncommon in industrial control panels to have have multiple 120VAC transformers with their primary feeds distributed among the 3-phase feed lines. This will result in multiple 120VAC lines in the enclosure with up to three different phase relationships. So red is only red in terms of the voltage present on the line (120 VAC). In this case all reds are not the same. This generally isn't an issue. But if two reds come together that are not in phase (two relay contacts from two different power supplies feeding a single input point) that is bad juju.

As Aabeck stated the color distinction is related to voltage AND function. If the 120VAC is not intended for control but is intended for power it shouldn't be red. If the 240VAC is intended for control it should be red.

Keith
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Old April 1st, 2020, 12:02 PM   #20
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Let’s start at the beginning: is this control panel being installed in a commercial or industrial building?

That may make a difference on the wire colors.
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Old April 1st, 2020, 12:44 PM   #21
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Originally Posted by dogleg43 View Post
I disagree. If 480V is present then it is line (black). The 240V wiring would both be red.

Use wire numbers on everything.
I went and checked some of our panels. Our typical set up is 480 is the only supply power. So control power is fed by a step down transformer. From there thatís all considered control voltage so itís all red. As stated above we donít use any center tap or multiphase transformers for control power, so itís a single red conductor.

So I would agree with that. In my head I was thinking of supply not control.
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Old April 1st, 2020, 02:13 PM   #22
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Quote:
Originally Posted by kamenges View Post
What you are referring to here is a 480/240 single phase transformer that you are center grounding the secondary to get two separate 120VAC feeds. Do I have that right?

I don't want to say this isn't done but I think it is somewhat uncommon in industrial machinery. I have seen a case where this wiring was done but only one leg was used for the 120VAC feed to the cabinet. I think that is what is creating a little bit of confusion.

You need to be careful with this one. It isn't uncommon in industrial control panels to have have multiple 120VAC transformers with their primary feeds distributed among the 3-phase feed lines. This will result in multiple 120VAC lines in the enclosure with up to three different phase relationships. So red is only red in terms of the voltage present on the line (120 VAC). In this case all reds are not the same. This generally isn't an issue. But if two reds come together that are not in phase (two relay contacts from two different power supplies feeding a single input point) that is bad juju.

As Aabeck stated the color distinction is related to voltage AND function. If the 120VAC is not intended for control but is intended for power it shouldn't be red. If the 240VAC is intended for control it should be red.

Keith
Your assumptions are correct.
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Old April 1st, 2020, 02:14 PM   #23
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Quote:
Originally Posted by dogleg43 View Post
Letís start at the beginning: is this control panel being installed in a commercial or industrial building?

That may make a difference on the wire colors.
Industrial control panel on a machine.
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Old April 1st, 2020, 02:16 PM   #24
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Quote:
Originally Posted by Maxkling View Post
I went and checked some of our panels. Our typical set up is 480 is the only supply power. So control power is fed by a step down transformer. From there thatís all considered control voltage so itís all red. As stated above we donít use any center tap or multiphase transformers for control power, so itís a single red conductor.

So I would agree with that. In my head I was thinking of supply not control.

Thank you for going so far as to look.

I have just always been told to make one red, one black for my two hots.. then white for my neutral. It seems that was wrong this entire time.

So to recap, 240V systems could be black if I'm using it just to power something, but if it's for control, both should be red?
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Old April 1st, 2020, 02:40 PM   #25
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Quote:
Originally posted by Timeismoney08:

So to recap, 240V systems could be black if I'm using it just to power something, but if it's for control, both should be red?
That's the way I have always interpreted it.

As I said above, your method of deriving 120VAC, while neither wrong nor completely uncommon, is not the norm that most run into when they crack open an industrial control enclosure. I would recommend you make clear what you are doing with some form of signage and, as was stated before, make sure all the wires are labelled.

Keith
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Old April 1st, 2020, 04:55 PM   #26
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Quote:
Originally Posted by Timeismoney08 View Post
Thank you for going so far as to look.

I have just always been told to make one red, one black for my two hots.. then white for my neutral. It seems that was wrong this entire time.

So to recap, 240V systems could be black if I'm using it just to power something, but if it's for control, both should be red?
If it is for controls, SOURCED WITHIN THE SAME PANEL it would be red. If the 240V used for control is coming from OUTSIDE of the panel and NOT DISCONNECTED by the main disconnect for it, then it would be yellow.


I have never seen anyone use a 120/240V center tapped secondary of a transformer within a panel to derive control power, it's always just one secondary 120V circuit. Cleaner that way. If your line source is 120/240V and inside the panel, you tap one of the legs to be the 120V control source, then after the control fuse (that would be required), I would change to red wire. But the 240V inside of the panel would be black all the way.
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Old April 1st, 2020, 06:30 PM   #27
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Quote:
Originally Posted by PLCnovice61 View Post
Hi all you people in the USA, it is funny to me, just about no matter what it is, you have to be different than nearly all the rest of the world, even colours of wires, the rest of the world know that phase colour 240v was red, now can be red or brown, neutral was black can now be black or blue, Earth wire was green but is now green/yellow, just saying, lol
This what I usually see in foreign lands and on Euro based foreign equipment.
is it how it should be?
.
Blue = 0 DC or Neutral AC
Brown = 24 AC, 24 DC, 240 AC or anything > 0 Volts
Green/Yellow Stripe = Ground

Last edited by Dayvieboy; April 1st, 2020 at 06:36 PM. Reason: Clean up
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Old April 2nd, 2020, 06:54 AM   #28
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Quote:
Originally Posted by Dayvieboy View Post
This what I usually see in foreign lands and on Euro based foreign equipment.
is it how it should be?
.
Blue = 0 DC or Neutral AC
Brown = 24 AC, 24 DC, 240 AC or anything > 0 Volts
Green/Yellow Stripe = Ground
That used to be the standard but not anymore. The "brown-blue-black" mantra still works for cables and sensors but not for panel wiring.
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Old April 2nd, 2020, 05:02 PM   #29
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Quote:
Originally Posted by jraef View Post
If the 240V used for control is coming from OUTSIDE of the panel and NOT DISCONNECTED by the main disconnect for it, then it would be yellow.

It would be orange according to UL standards, which also ties in with EU/BS standards too, not yellow.
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Old April 2nd, 2020, 09:07 PM   #30
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OK, so the discussion is about the COLOUR of the insulation on cables.

We have discovered there are conflicts between domestic and industrial systems, and we have discovered conflicts between systems built to different (e.g. national) standards.


In my opinion, do NOT rely on cable insulation colours on a panel you are unfamiliar with. You open a panel door, and NOWHERE will it state the "standard" it was built to, and the wire that is covered in coloured plastic has absolutely no idea what it is carrying !

I spent over 20 years working in (mostly UK) breweries that had their own wiring "standards" that they had used for donkeys years, and to adopt any suggested or imposed "national" standards would have meant their technicians would have to learn, and understand, 2 or more conflicting standards.

Never take anything for granted, panels will not always follow code.
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