Rat's Nest - a PSA about panel sealing

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strantor

Joined Oct 3, 2010
5,025
This is copied from my Facebook business page. Thought I would share it here too.

The term "Rat's Nest" in the context of a control panel, typically refers to the state of the wires inside, and how they are routed. A "Rat's Nest" is the same thing as a "Spaghetti Bowl;" a panel where wires are just all over the place, in bundles and knots. Less commonly, it can refer to a literal Rat's nest inside a control panel.

Strantor received a call today about a CNC mill with a spindle drive that was experiencing intermittent failure. Upon arrival, the pictured rodent squatter situation was discovered. The rat(s) who built this cozy mattress opted to use invaluable system drawings and other important documentation which are no longer available from the manufacturer. Dried evidence of fluid waste was found in places that could have contributed to the problem. Luckily, no wires (that we know of) were harmed in the process.

This post is a PSA about panel sealing. Panels should be reasonably well sealed to keep out dust and debris. Openings large enough for rats to enter, lead to premature failure. Conductive dust, especially in a machine shop environment, gets into electronics and shorts out components. Some components on circuit boards have static or magnetic fields which attract metallic dust. See the bottom of that panel? It's supposed to be white. If that much particulate has settled on the floor of the cabinet, imagine how much is caked on the control boards! Also it is impossible to control humidity (another enemy of electronics) inside a panel with gaping openings.

Conductive dust is bad. Humidity is bad. Rats are bad (they chew ANYTHING, including wires). Not to mention the biohazard for anyone who has to work in that panel (some things were "sticky"). Keep your panel gaskets in good order. Keep your fan filters and panels clean. Keep your knockout holes plugged. Your machines will last longer, I promise!
ratsnest1.jpg ratsnest2.jpg
 

ericgibbs

Joined Jan 29, 2010
8,586
hi S,
Sometime ago I was asked by a friend to fix his electronic organ,
He said some of the organ keys would not produce a sound.
Checking thru the wiring harness I found a mouse nest, the mice had chewed thru all the Green wires which were connected to the faulty keys.
None of the other coloured wires had been nibbled.
E
 

MaxHeadRoom

Joined Jul 18, 2013
18,864
Why anyone would leave 'Invaluable documentation' in the bottom of the cabinet is a puzzle!!
At least use the customary door pocket for them, or better still make copies and store in an archive somewhere, if the machine parameters where included and only hard copies exist and the machines has a memory dump, in the case of a MTB out of businesses, the machine turns into a lump of steel!. :rolleyes:
Max.
 

Janis59

Joined Aug 21, 2017
742
Our elevator was build at 1911. The cabling there seems two orders of magnitude more tragic than Your pictures. The over century thick pigeon junk is rotting everywhere on the cabling and relays, the hundreds of un-doccumented shortenings stays in all possible places, the all relays are going on 110 Volts (what an anachronism!) thus it are fed by surplus autotransformer what had been burned and rewound at least dozen of times, but it is still operable and each few years under hardest "motivation" the assurance certificate is happen be obtained from the inspectors. Probably it may be most eldest elevator in Riga city.
 

Janis59

Joined Aug 21, 2017
742
But about rats nests.... few month ago I was invited to Poland to find out why their machinery are not working. They paid well so I travelled those 1,5 thous km to find that machinery is built in east-Ukraina by means of students and russia `experts`, who seems pushed into job the all negacy what they think about Western life and freedoms.
Example - 10 kW freezer unit. Motor is silent. Open the driver box - from 6 switchers only one is connected somewhere, other all are nude. Circuit is unexisting, in box are some strange russian relays what was not known beforehand (oh, they have some original constructions!), later we examined those are phase control relay and time-shift relay (both defected). And connector poles, poles, hundreds of screw-poles full of damn red and green wires. (Which to touch, red or green to have an grand boom!?)
Try to understand from where the motor gets the current. Wire comes to pole, goes to second pole, then to third, to thirty third, and reverts back to where it comes from, without of branching or any touch the in-coming current.... The brilliant engineering immitator job.
So, we plucked off anything, now cooler is working but 9/10 of poles staid unused.
Other sample - they freeze the three barrels each 200 liters of ethylene glycol. All was used the blue type of plastic barrels under thermo-insulator layer. BUT the barrels was mount on the metal ring of 60 cm diameter giving the support for weight. As soon we got a cool, barrels downisde blushed round and then begun to drip more and more violent. To say honestly I didn knew that those barrels are not permitting the perimeter only support for long periods, but damn, that is produced in russian fabrique.... And walk into tonn much of ethylene pool is damn unhealthy. Good that Polish guys was found in the internet that ethylene poisoning is well cured by plenty of wine drinking, thus I have an immagination that I understand something out of Polish vines :).
How good and mind-calming is to know that IF ANY day will come when russia schizophrenic leader will push the nuclear button (those what is even larger than those mister`s Trumpf owning) the all aggregates of it was created by the same manner and the same efficiency. Thus I can sleep well for a while not knowing the difference between red and green wires.
 

KJ6EAD

Joined Apr 30, 2011
1,568
Our elevator was build at 1911. The cabling there seems two orders of magnitude more tragic than Your pictures. The over century thick pigeon junk is rotting everywhere on the cabling and relays, the hundreds of un-doccumented shortenings stays in all possible places, the all relays are going on 110 Volts (what an anachronism!) thus it are fed by surplus autotransformer what had been burned and rewound at least dozen of times, but it is still operable and each few years under hardest "motivation" the assurance certificate is happen be obtained from the inspectors. Probably it may be most eldest elevator in Riga city.
There are paternosters still operating in Prague.
 

RichardO

Joined May 4, 2013
2,273
There are paternosters still operating in Prague.
I have learned a new word today: "paternoster". That elevator is a true nightmare.

@Janis59
Have you ever ridden a paternoster? Do you still have all of your limbs? :eek:


edit: Added questions to janis59.
 
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