Panel Building

There is nothing like looking at a well designed panel. I am often awed when I see the precise organization of thousands of wires so neatly tucked into such a small space.

I respect panel builders, and most of the time the documentation and wire numbering scheme make my day a pleasent one. But...

What are the standards used for "extra" wire?

It is not uncommon for me to have to replace an A/B selector switch with a Cutler Hammer switch, due to inventory issues.

This should be simple, yet the contact layout on the selector switches is just enough to leave the wire 1/2 inch short!

This leaves me a couple of options.

I can either splice a pigtail on the wire, and begin the process of destroying the integrity of the "good looking" panel.

Or, I can clip the 1,956 wire ties that make everything look pretty, replace the wire, with one 1/2 inch longer, and replace the 1,956 wire ties...

Unfortunately, with production down, I often resort to plan A, with the intention of getting back to it...

In my "sparky" training, I was always taught to leave a "handful" of wire.

I'm just curious as to what the panel building specs are.

When wiring push buttons bring the wire out of the tied bundle and out away from the surface to which the button is mounted, up above the switch contact block, then do a nice u-turn back down to the switch terminals. A little practice keeps the U-loops uniform and good looking.

Don't know if it applies over there, but the EN regs we build to over here state there should be at least enough spare cable to re-terminate at least another TWO times on any given termination.....

Your panel builders are cutting their wires way to tight/short if a 1/2" makes a difference. They should have at least a couple of inches of spare in the wire trough. Good panelbuilders know this, now if I can just get the pipe fitters to leave some extra air-line.

I can either splice a pigtail on the wire, and begin the process of destroying the integrity of the "good looking" panel.

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Regulations/standards (NFPA 79) states " Conductors and cables shall be run without splices from terminal to terminal".

I definitely agree the panel builder is worrying to much about aesthetics than proper wiring...in other words they shouldnt be too short. Alas it is a common problem because different brand pushbutoon/switches etc position differently.

If I have the time and the wire goes to a terminal I will replace the wire. There have been numerous occasions because of downtime issues that I have had to resort to splicing. I have dealt with numerous cabinets where the wire(s) did not terminate but ran long distances through raceway/conduit so again had to resort to splicing.
* A little cheat of mine is put in a terminal block when possible, this allows a cleaner looking connection, can be labeled properly and allows for more connections to be added as needed*

I have had issues with IEC style switches not being mechanically durable so usually replace them with a NEMA style switch. In most cases there are issues with the wiring so I have used a splice to make the machine run but will then mount a terminal block and prepare the machine for the eventual conversion to the new style switches/pushbuttons. Once setup any time you have a switch or PB go bad its a simple matter of running old wire to terminal and run new wires to switch/PB.

Good panelbuilders know this, now if I can just get the pipe fitters to leave some extra air-line.

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Ahh yes, move a machine etc and it has a hose line with quick disconnect...its always 2 inches from the air line.
OR
You need to use an impact/speed wrench and have 50 or 100 foot of air line...nearest connection is either 51 feet or 101 feet away. Murphy at work.

That too, but they always plumb a valve backwords and don't leave enough slack to swap the connections. GRrrrrr

This is the Golden Rule

The Golden Rule states: The one with the gold makes the rules!

I ran a panel shop for a long time, then designed control systems (panels included) as a consultant. At that point, I was on the other side, the side of the buyer. I "farmed out" my panels for build by several local panel shops.

I took a few well-spent hours to make up a specification that I sent to these panel venders that stated EVERYTHING I wanted when it came to control panels. I have attached a version for everyone to view.

If a panel vendor "cheated" with shoddy workmanship, I was always covered.

Most of our customers now have a detailed spec with everything spelled out in detail.

As an OEM, the problem that we run up against is when we quote to that spec and someone else does not. The other guy may lose his shirt later, but we lost the job.

Alaric's point is right on.

Loop around where possible so that you can re-terminate if necessary. If your switches are in a door, loop low enough from the panel wall to the door so you have extra wire. Wire ducting is a great place to store the extra wire going to panel mounted devices.