6amp MCB Trips After 5 Mins :-S

jordyboy004 · Nov 23, 2007

Hi Everyone,I Have Been Called Out To A Job With A Problem On The Lighting Circuit. Couldnt Spend Too Much Time On It As It Was Last Thing Today (Friday) The Breaker Holds In For Approx 5mins And Then Trips, When Tested I Found It Had A Short Between Phase/Earth AND Phase/Neutral, Surely A Short Circuit Would Take The Trip Out Straight Away And Wouldnt Not Hold In. I Cant Think Of What The Problem Is...........Help lol

yorkshiresparky · Nov 25, 2007

Before testing did you remove all your lamps? Try a new mcb first me thinks

jordyboy004 · Nov 26, 2007

yeah all lamps were removed and yeah i did do that first lol. im stumped, anyways traced the wire back to a JB, was the switch wire for the kitchen in the end, took it out and replaced it with a new cable. still not sure what the fault was as the wire went under her bathroom, so i found a new and easier route with my cable back to the switch. thanks anyways

Submains · Nov 28, 2007

If you used an IR tester to ascertain the "dead short" then alarm bells should have started ringing as to why the time delay to disconnect.
Continuity of CPC. R2 test on that circuit. Main earth bonding/earth loop all contribute to the disconnection time.