Light circuit suddenly trips and cannot take more than 20 watts

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Heard of them but never seen one .   

Quick story;

I committed the dreaded compression fault as an apprentice and never forgot it .       I started in industry on maintenance,  spark had  me and a mech. fitter apprentii  updating some awkward  pneumatic  /elctro  valves on a machine .

I fitted a strip of the original  " Choc  Bloc "  connectors  with 24V  control wiring  .    Everything working again until machine was halfway through it's cycle  and blowing the control fuse .  

Sparks left me to sort it  until I'd blown a boxful of fuses  ...he stepped in and showed me a couple of things I've never forgotten  .

Thing (1)     Stop  going at it like a demented chicken ...stop & take stock .... it was fine before so what have you done thats different .... the valves , the flexibles, the      

                        connectors .  

Thing (2)    Ask the operator  where  it stops .  

Thing (3)    Remove the control fuse and connect a  24V lamp  across  the carrier  , when it lights up , thats the fault to earth .

Thing (4)   OK   it stops every time  the cutting head needs to raise away from the steel bar .....you know which valve directs the cutting head ...the wiring  is OK .... but 

                               you've fixed the  "Choc Bloc"   to the machine with a 2BA  pin  which is too big  and too tight, it shorts the  terminal to earth  that operates the solenoid that                                    lets   compressed air through to the head and  returns it .  

That was about 400 years ago .  

 
I used an impact driver today.

I was putting in No12 x 3" screws to hold a gate up, which is what it's designed for, not cable clamp screws.

 
What were the IR tests prior to finding the fault and afterwards?
>2000 before and afterwards, that's what is weird, and continuity was fine. My Multifunction tester is a Kewtech KT63, maybe a better model would pick up on IR better. Continuity was good. Just pressure on the cable caused this fault which is a lesson learnt in using impact drivers instead of screwdrivers!

I used an impact driver today.

I was putting in No12 x 3" screws to hold a gate up, which is what it's designed for, not cable clamp screws.
🙂 Very true. We do things like this to speed a job up, but this one resulted in spending more time finding the fault. Screwdrivers from now on!!!

 
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