Actual Trip Value

[NrVolts]

i know some, probably tel will make a joke about this, ..i can see it coming so i'l get in first :this isnt about bad value day outs sorry tel
So ive read many posts on this subject and opinion seems divided.
On testing a MEM 100he mains switch rcd with all breakers off,link from the main switch to neutral bar disconnected(croc clamped meter ends to neutral at switch and line on the main bus bar and lastly clamped third lead to earth bar in comsumer unit). energized switch with ramp test selected on meter,selected test ..the rcd tripped at 23 mA.Cant find any technical data about this device to i woundered what thoughts are about this.This board has given random nuisance tripping for a very long time,but with all ccts disconnected i thought ide get a higher reading of maybe 28 mA ..Any advice much appreciated

 

[Darkwood]

You standard tests ie 0.5 rating of rcd will ensure the rcd isnt too sensitive so in respect of a 30mA rcd it shouldn't trip at 15mA but obviously must trip before or at its rated value, its common for rcd's to be set halfway between 15 and 30 as this allows variants like temp etc that can effect the sensitivity of the device so 23mA is common tripping current for a 30mA rcd.
30mA rcd will often be found to operate 18-28 mA.

 

[telectrix]

agreed. ^^^^ . @ nrvolts, the way you have connected your leads looks about right, but mind you don't trip over them.

 

[chrish_1977]

I had one the other day, replaced a load I accessories and then the rcd wouldn't hold (previously ok) did end to end on ring final, found a fault neutral to earth, anyway, testing the rcd with mft 1553 and It kept failing x1, took a bit of finding too.

 

[NrVolts]

should have mentioned it was 30mA rating..owps.I think ive found the culprit,the freezer in the garage is soaking wet with condensation.gonna ask they empty it and switch off for a few weeks to see what happens.

oh magoo (yes i mean you tel ) hes done it again.:'( hahahahha
Many thanks guys ,thanks darkwood