CT & PT Insulation colour 5

[jacphi]

our local standard requires neutral wire colour code to be white.can somebody tell me if i have to follow this for the neutral of CT's and PT's used for metering and protection.

 

[peebee]

Depends on your local standards, I guess. Where are you located?

Usually, though, control wiring (such as PT & CT wiring) can be whatever color you please.

Might wanna check with your local authority.

 

[busbar]

In both cases the wire sounds like it is used as a grounded-circuit conductor, and color could conceivably be enforced under that aspect.

 

[peebee]

Oops, I just noticed you spell color with a "u". Guess you're not in the US. Which means "don't listen to anything peebee has to say".

 

[busbar]

Same for busbar.

 

[jacphi]

interesting finding peebee..you are right i am living in saudi arabia. most of the stds/codes used here are all american.but the local std states that the wire insulation COLOR for neutral should be white. i am confused in regards to the CT's and PT's. can the 'XO' of the Ct be considered as neutral.

 

[peebee]

It's a tough question.

Assumptions:
1. Your neutral is grounded.
2. This is field-installed wiring, routed outside of a switchboard. This is not factory-installed wiring, and it's not all contained within a switchboard. You're routing from a CT cabinet or similar, via conduit or similar, to some remote devices.
3. This is considered Class 1 control wiring per NEC 725.

That said, I can't find anything in the NEC that would permit you're neutral to be any color but white or gray (grey?). . . . except possibly NEC 725.25 Exception No. 1. And even then, I think it could possibly be interpreted either way . . . . Unfortunately, I've always found 725 to be a very difficult article to read/understand/apply.

Your best bet is probably to call up your local inspector or plan reviewer, and see what he thinks.

Has this already been installed? Do you have any good reason to make it some color other than white or gray?

Also, please note that if this is factory-installed wiring located in a switchboard, then most likely the wiring is type SIS, which is ALWAYS gray in color, and factory wiring does not fall under the scope of the NEC.

Hope this vague answer helps.

And "wahala-wasahala", or however you say "welcome" in Saudi Arabia (that one phrase constitutes my entire Arabic vocabulary).

 

[busbar]

One comment — NEMA Std ICS1-2000 for Industrial Control Panels §7.6 states “…white indicates the grounded neutral conductor or the circuit.” I understand that to mean that for internal wiring, white as grounded-circuit conductor is acceptable but not mandatory.

 

[jacphi]

let me tell you the exact situation
i have a control gear with motor starters using 239 multilin relays .the secondary of the phase ct's used have x1 & x2. x1 is the ungrounded circuit conductor and x2 is the grounded circuit conductor. the color coding used for the x1 is white and for x2 is black. the inspector was arguing that the color be reversed,as the local std says all neutral should be white. we told him that nec or the local stds does not state the conductors used for cts and pts be considered for the color coding. but of no use!!! can you help to support our argument. by the way
Ahlan wa Sahlan - Arabic for welcome

 

[peebee]

Sounds like you're stuck. . . .

 

[busbar]

Doing things completely opposite of a recognized practice may be troublesome during operation/debugging/troubleshooting.

 

[buzzp]

There is two solutions
1. Route the conductor through the CT the other direction (change all of them) and reverse your X1 X2 connections OR
2. Just reverse the connections. Verify with 239 literature that this is not going to screw up the power readings (PF), solution #1 above should not mess with any functionality or measuring of the 239.
You have to work with your inspector, if this is the way he wants it then make it that way in order to keep relations good because, at least in the US, he can make life hard for you.

 

[jghrist]

I would agree that in this single phase application, where the two conductors are black and white, the white should be used for the grounded conductor.

What do you do for 3ø wye connected CTs and VTs? If the NEC wire colors are deemed to be required for CT and VT cables, how do you use standard ICEA control cable color codes? Method 3 Table K-2 4/c cable has Black, Red, Blue, Orange. No White for grounded conductor. Method 1 Table K-1 has Black, White, Red, Green. To use White for the grounded conductor, you would have to use Green as a phase conductor. What I have done is to use the Green as the grounded conductor if using Table K-1 and use Blue, tagged as Green if using Table K-2.

 

[busbar]

The ICEA “K2” colors and recoding scheme seems to have been addressed in 99NEC200-6(e) Ex. 1: Where the conditions of maintenance and supervision… grounded conductors in multiconductor cables identified at their terminations at the time of installation…

 

[BJC]

What ever colour you use, suggest the following as well.
Label all wires as they appear on the shecmatic ( online, synchronizing diagram etc) with permenant slip on wire sleeves. IF you designing the system prefix the wires with a "CT" or "PT". If you didn't design the equipmentm then tag tag the conductors some way during commissioning.
I like to specift that CT circuit conductors a larger size (#10 over here where we say color). The larger wire may not be necessary but the size make it identifable.