wire insulation under screw terminal
wire insulation under screw terminal
(OP)
I was wondering how bad this can be,
It was under fuse block screw terminal, what is the potential hazard? Any information would be much appreciated. I have attached a photo of the wires.
It was under fuse block screw terminal, what is the potential hazard? Any information would be much appreciated. I have attached a photo of the wires.





RE: wire insulation under screw terminal
Total failure: No signal gets through, system burns up.
Total failure: No signal gets through, system never starts.
Total operation. No signal gets through, system never stops.
Total operation. Every signal gets through, system never stops.
Sometimes failure, sometimes operation: Signal/power gets through until plastic melts, then it either never gets through, or never stops.
RE: wire insulation under screw terminal
RE: wire insulation under screw terminal
Bill
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"Why not the best?"
Jimmy Carter
RE: wire insulation under screw terminal
RE: wire insulation under screw terminal
Maybe track down the actual installation instructions for those exact devices (circuit breakers or whatever they are). If the manufacturer has as many lawyers as average, then there will be a 2-foot square sheet of instructions with every detail described.
RE: wire insulation under screw terminal
James
RE: wire insulation under screw terminal
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: wire insulation under screw terminal
Main reason is during vibration over time. When the screw terminal gets loose, the screw terminal backs off of the wire, but the insulation is still being crimped by the screw terminal. Now if its 3 phase you have a single phase condition. If its other control signals you lose these signals.
I have had this problem on some terminations, to whole cabinets where I had to get who terminated back in to restrip the wire terminations and retighten terminals.
This is my biggest gripe about electricians.
RE: wire insulation under screw terminal
RE: wire insulation under screw terminal
RE: wire insulation under screw terminal
For an assembly like this, UL/IEC 60950 or UL/IEC 61010 will define minimum spacing requirements for how close a finger model can get to an exposed conductor. These look applicable to the second wire from the right on the bottom. There are minimum force requirements to pull the wire out. It is required to 'clamp the conductor between metal surfaces', so I'd say clamped insulation violates that one. Other sections say as long as you can bend a similar size wire in any direction without making contact with another conductive part then it is fine.
Again, these are design guidelines. The installer has the ultimate responsibility to do it correctly.
Z
RE: wire insulation under screw terminal
RE: wire insulation under screw terminal
few words can describe that workmanship (that can be printed in public.)
This is why most industrial projects specify crimped terms.
If you are OEM then you are just buying warranty claims ,
If you are client side then YOUR projects are going to be unreliable with intermittent events
that level of inattention to tradesmanship is indicative of a second rate effort by the build team and thier leadership
Ok that's the rant over with
Set up a QA "team" walk through the terms and insist on seeing a tiny bit of daylight between the terminal and the insulation.
Note them, then call the supplier / sub contractor for rectification - (or back charge)
It would be a very easy claim to make against your local standards or even "not done in a tradesman like manner"
don't forget your client (internal or external) will not think well of you if the installation trips /fails / goes wrong
having said all that have a great day and enjoy the ride
Don
RE: wire insulation under screw terminal