terminal lugs becoming loose
terminal lugs becoming loose
(OP)
terminal lugs becoming loose causing resistance and eventually heating the terminal strip/block, would it be Ok to screw/bolt two lugs together and bypass the terminal block. What are pros if any, what are the cons






RE: terminal lugs becoming loose
RE: terminal lugs becoming loose
RE: terminal lugs becoming loose
There are several ways in which poor workman ship may lead to loosening that may also apply to bolting the lugs together.
When a terminal lug is damaged beyond repair, it is sometimes bypassed by bolting as you suggest. Issues are difficulty trouble shooting and more time consumed changing out components.
After a connection has caused issues due to loosening, the strand surfaces of the cable are often compromised by a film of copper oxide. If the cable is not thoroughly cleaned, the repair may also loosen.
Bill
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"Why not the best?"
Jimmy Carter
RE: terminal lugs becoming loose
Rafiq Bulsara
http://www.srengineersct.com
RE: terminal lugs becoming loose
RE: terminal lugs becoming loose
As Rafiq stated, that is not an acceptable method of connection.
There may be a number of reasons why terminal block connections come loose, including vibration, workers not ensuring that they're tight in the first place, termination of more than one wire in a slot, and others.
Cage Clamp is one manufacturer's means of dealing with such things, though its not without its drawbacks either (not including the general dislike of them by trades).
I'd be looking as to why the connections are coming loose before doing anything else.
RE: terminal lugs becoming loose
Many motors have ring lugs installed on the leads. In such a case ir is common practice to install a ring lug on the incoming feeder and bolt them together.
Over the years I have come across a number of motors with a terminal block in the motor junction box or "pecker head". From time to time we find that a loose connection has destroyed one section of the terminal block. A common repair is to clean the lugs and bolt them together and tape them up. IWhile not recommended for new installations, I know of no prohibition to using more than one type of approved connection in one location.
Bill
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"Why not the best?"
Jimmy Carter
RE: terminal lugs becoming loose
Any other way will result in a new failure, even a fire and consequent damage.
rasevskii
RE: terminal lugs becoming loose
In my experience, bolted & taped lug to lug connections have proved to be a good flexible solution to a fairly universal problem & is standard practice.
The hassle factor of taping is a small price to pay & often prevents secondary damage caused by loose conections related to inflexible terminal blocks.
As mentioned elsewhere, care must be taken in selecting the correct terminal lugs & crimp method for supply cable & motor winding conductors.
RE: terminal lugs becoming loose
A bolted connection must also be made with the appropriate washers and torqued properly, as the issues with thermal cycling and loosening are similar to those with a terminal block.
RE: terminal lugs becoming loose
Bill
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"Why not the best?"
Jimmy Carter
RE: terminal lugs becoming loose
rmw
RE: terminal lugs becoming loose
Most failures I've seen in small motors are caused by tarnished or corroded lugs on tarnished terminals resulting in a joint which runs hot. It is laziness on the part of the electricians - sometimes the only way to get it done right is to inspect it and force them to rework bad joints. We massively reduced our number of failures by keeping the lugs and terminals bright. The drives which our analysis showed were most susceptible were typically high inertia fans, something we attributed to the high dissipation in the bad joint during acceleration.
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If we learn from our mistakes I'm getting a great education!
RE: terminal lugs becoming loose
And in one specific case I had to deal with aluminim wiring and lugs in a rotating machine - awful - couldn't keep them tight.
rmw
RE: terminal lugs becoming loose
I had assumed DIN rail terminal strip, though others also considered motor terminals and similar. I don't think the issue is exclusive to either, though I admit its quite hard to bolt two bootlace crimps together.