Wire Numbering

[HereForBeer]

I was troubleshooting inside a control panel this morning.. It was a little frustrating because a component wasn't getting the power it needs but all the 24VDC coming from the terminal strip had the same wire number.

Is that normal or common?

It would of helped me out a lot more if the 24VDC wires coming from 24VDC jumpered terminal blocks had their own individual wire numbers!

 

[Bit_Bucket_07]

I would say that it's not a terribly uncommon practice, in my experience. What really bugs me is when a panel builder daisy chains power wiring to multiple devices, rather than installing separate wiring for each device.

 

[Snap25]

A lot of panels I've worked in had the "wire shouldn't change numbers unless it electrically changes" approach. All the 24vdc wires coming out of the terminal block had the same numbers. Since its logically the same wire.

 

[labeledas]

What really bugs me is when a panel builder daisy chains power wiring to multiple devices, rather than installing separate wiring for each device.

yeah I had that happen recently and I had to swap a device in the middle of the chain without disturbing the down stream devices

 

[g.mccormick]

A lot of panels I've worked in had the "wire shouldn't change numbers unless it electrically changes" approach. All the 24vdc wires coming out of the terminal block had the same numbers. Since its logically the same wire.

That is the way I always do it. To me, having every wire number be different even if they are the same is bus/signal/etc is extremely frustrating.

One thing that is helpful is to call out specific terminal blocks for the wire.

 

[sparkyinak]

My circuit/ wiring numbering typically have the same number when the have the same potential through all processes. The number changes when the potential changes. The numbering also collates to where the circuit is at on the schematics. Single digits are power circuits. Two or more digits are control circuits where all but the last number is the rung or row number and the last digit is where the wire lies within the circuit. For example "235" can be found on roll 23, center of the of the rung.

When multiple wires with the same potential has the same number, makes it easier to troubleshoot. I even differenate power circuits as fused or not. My control power "5" indicates it's hot off the power supply to the line side of OCPD. on the load side, the "5" becomes "5A" indicating it's protected. For multiple fuses, I can use B, C, D, etc.

Everyone has their methodology that works for them. Mine I feel helps with trouble shooting, navigTing the schematics, and expanding in the future with minimum headaches.

 

[dogleg43]

A lot of panels I've worked in had the "wire shouldn't change numbers unless it electrically changes" approach. All the 24vdc wires coming out of the terminal block had the same numbers. Since its logically the same wire.

Ditto for this approach. Electrically it is the same.

 

[brendan.buchan]

I was troubleshooting inside a control panel this morning.. It was a little frustrating because a component wasn't getting the power it needs but all the 24VDC coming from the terminal strip had the same wire number.

Is that normal or common?

It would of helped me out a lot more if the 24VDC wires coming from 24VDC jumpered terminal blocks had their own individual wire numbers!

This is standard practice in my opinion.

A wire number should only change when it is being altered or switched in some way, whether that is through a push button contact, circuit breaker, disconnect, etc.

 

[BobB]

Standard - so is looping.

 

[keithkyll]

standard - so is looping.

+1

 

[sparksy@gage]

Worked on some old European panels a few years back and wire numbers changed at each end of a wire to connection.
Ie wire was "1 at its start and then "2" at its end to say a terminal strip, then started again as "3"and continued to "4" at its end.

 

[AutoMax]

Worked on some old European panels a few years back and wire numbers changed at each end of a wire to connection.
Ie wire was "1 at its start and then "2" at its end to say a terminal strip, then started again as "3"and continued to "4" at its end.

I've seen that a lot in European (especially Scandinavian) panels. It can be a royal pain when you don't have prints. Typically you can puzzle out the pattern after you've traced a couple circuits, but it's a bother.

 

[MarkNightingale]

We have a lot of German panels here, and no 2 ends of the same cable have the same number on it.

They use the number of the device, say a relay, and then add which terminal number the cable goes into.

I have been told they do this so they don't have to have skilled panel wirers.

Oh, and all the wires are cut, numbered, and crimped by a machine.

Cheers

Mark

 

[PLC Pie Guy]

yeah I had that happen recently and I had to swap a device in the middle of the chain without disturbing the down stream devices

This is when you get to pull out the alligator clip jumpers and it makes you look like a bomb technician, jumping wires in a tangled frenzy, sweating just a bit in suspense hoping the line doesn't go down and you come out looking like a rock star!

 

[JohnCalderwood]

Some of the panels we get, especially from German suppliers, have no wire numbers at all.

You have to use the terminal number and the drawings to decipher what signal the wire is supposed to be, and the colour of the wire sometimes gives you a hint of the voltage and/or the source.

This recent (last week) one, the remote I/O panel, most of the terminals had the designation X21, but we have to use the section of the drawings to determine the prefix - for example drawing section P3 is called P3-X21, M1 is called M1-X21.
It was determined in the contract that we were responsible for the electrical installation, they did the mechanical and the commissioning...I do not think we made too many mistakes/mix-ups with the terminals, but I know of at least one significant one..

Makes later diagnostics difficult, no wonder we get many panels that have the betaduct trunking lids removed as electricians manually trace wires when they have an issue, or cannot find a signal they need.