My latest CDU

[nickblake]

View attachment 6109 Here a pic of my latest CDU , this is the one where we have a fault on a circuit which i cant find , my suspicians is a nail of screw through a cable its intermitant but testing even at 1000 volts doesnt show it , i tested the meter on my apprentice it works fine (joking honest lol) but a pain, i will find it you can switch it on will work for hours then go bang big style so i have resorted to disconnecting all parts of the circuit and reconnecting each leg switch wire one by one till i find it its a swine it goes bang whip the circuit tails out and nothing all clear R1R2 are fine 0.69 insulation >200 meg Zs 0.98 wiard ill say :thinking:

 

[telectrix]

nick. i had a similar scenario where the fault was tripping the mcb sometimes and the rcd others. IR readings were fine. turned out to be an intermittent s/c L/E between the phase conductor and the galv. back box of an old outside socket.

 

[TinyT]

Best CCU i have ever seen!!!

 

[DurhamSparky]

Ip rating on switch under CU looks bit dodgy!!!

 

[not clever]

Check the loft, you might find a wasp nest covering a bare cable or junction point, all is well on the circuit untill a wasp gets fried on the conductors tripping the mcb, you test the circuit reset the circuit & all is well for awhile then bang off it goes again.

 

[nickblake]

Just to up date , duram the back box has now been replaced as i wired in the central heating today and investigated the fault ,which reared its ugly head today this time i managed to get a reading after disconnecting all the wires it still was clear untill i moved some wiring in the loft just above the switch drops and it tripped , testing revealed a low insulation reading of 0.06 at the board so i traced it back and got it down to 0.00 nice it was between the L and the CPC of the switch wire to a switch pulled out the cable luckily id capped them and replaced it no marks nothing but the insulation was down to earth tested the cable when i had been removed and it was still down to earth new cable in and retested all hunky dory and me smiling , just a very odd one Prysmann cable too