How not to... is just that. Examples of how not to do something.
Industrial control panels regularly last decades. They are often designed with the future in mind: that is to say, they are made to be simple, protected, well documented and with ample space for future additions. Often, they are well designed and leave the panel shop in good condition, before years of field abuse hit them.
However, in the PanelGore subreddit, you can see wonderful examples of how not to build panels.
Consider the following panel. Note the absurd number of unlabeled wires. Even if they were labeled, this would be difficult to troubleshoot. The cabinet is obviously too small, as they ran wires over (rather than around) the relays. For some reason beyond me, the components are not connected to the backplane. At least one energized relay is being supported by the wires! It is barely worth noting that the terminal blocks are unlabeled.
If I were working at this site, I would recommend ripping the whole thing out and re-doing it. There are probably smaller relays that might make it work, but I doubt it would make sense to keep. I bet there is no drawing.
If management really wanted, you could start tracing wires in it. I would want it shut off and start by warning them something will be loose. I would bring some wrap-around labels and start a drawing... Then I would sketch it up and see what the circuit really was. If this is mostly signals, you might be able to get away with terminals and a very small PLC... but I would not get my hopes up.
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Or this beauty. This one does appear to have some labels, and some degree of terminal blocks. I have a funny feeling those cards are not given adequate clearance and that a number of the wires run up from the bottom are landed directly on the PLC cards. How would you swap the PLCs later on?
With this hot mess, I can think of little more than shortening the wires. The cabinet is too small to do any re-work and the I/O is already fairly compact. If they only had one of those racks, this would probably be a nice little panel.
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This one looks closer to the bad end of what I have dealt with. There are terminal strips, even if they are poorly labeled. The cabinet is too tight, there is no Panduit to keep in the wires and things are laced directly across where the door should swing. Troubleshooting this would be unpleasant, but feasible. Some stuff is hanging, but it could be cleaned up in just a day or two.
I would want this off before I finished opening it, and I would open it *very* carefully. While it remained off, I would try to mount all of the parts that are not currently mounted, then tighten everything as I went around. Add in some wire supports for the door and labels, then try it out.
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It is harder to judge a refurbished panel than a new one. However, judgement is still worth passing. It looks like a new backplane was added, but the wires were never put into a set of terminals first. Hence, this refurb probably took the system down for a bit. Little care was put into cleaning up the cabinet wires and, frankly, just looking at the outlet hurts me.
At this point, it would make little sense to pull out that backplane. If you could add in terminal blocks everywhere and start running new wires between the old points, you could probably clean most of it up.
Even if I was not asked, I would probably fix the abomination that is that outlet
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This next cabinet is an example of either an engineer, grad student or apprentice getting free-reign of a system. It is just a wee-bit too small and it is squandered. Only one phase of the disconnect is used.
If I were servicing this, I would secure the parts and shorten the wires. There is not enough space to do much else.
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The following cabinet is only an honorable mention. It is clearly for a surge suppression unit, but does not have the ground on both sides. It is also hanging.
Add some DIN rail and ground it. This appears to be a pull-box anyway. Why is this even here?
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This cabinet has no box. I imagine it did save money on the build, but leaves about $25,000 of parts free to be damaged by... anything. Someone could drop something, trip into this, etc and take out a lot of gear. Also note the switch being used to collect heat on the side.
Seriously, buy a NEMA 3R box and toss this inside. It does not look like a significant amount of cost to protect your investment. Use a managed switch and DIN mount it.
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Finally, a piece that probably comes from a grad student, as no electrician, even an apprentice, would abuse wire in this manner.
If I were called to service this, I would walk away. Academics are unlikely to appreciate the bill, even if I were only shortening the wires. This looks like an OT security lab, not an industrial installation.
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