mcb help

[doglog]

hello
I have been called in to inspect a DB that has been soaked in a flood. The board is now dry but the MCBs have a problem. If I put the insulation resistance tester across the MCB, even if disconnected from board and final circuit, with the switch in OPEN i.e. OFF position I get a reading of about 0.20 meg. and with the swith closed i.e.ON I, as expected, get 0.00meg.
I have found an identical MCB which wasnt affected by the flood ( brand new i think) and the reading across MCB in OPEN i.e. OFF position I get >200meg as you would expect and CLOSED i.e. ON 0.00meg again as you would expect.
My collegue has 'tested' these MCBs i.e. tried them out and they seem to operate normally..even in OFF position there is no 'let through' of voltage as I would have expected given the 0.20meg reading
But I think the MCBs should be replaced as their integrity cannot now be guaranteed..
Has anyone come across this problem before??
Thanks for any help,
Doglog

 

[Sintra]

hello
I have been called in to inspect a DB that has been soaked in a flood. The board is now dry but the MCBs have a problem. If I put the insulation resistance tester across the MCB, even if disconnected from board and final circuit, with the switch in OPEN i.e. OFF position I get a reading of about 0.20 meg. and with the swith closed i.e.ON I, as expected, get 0.00meg.
I have found an identical MCB which wasnt affected by the flood ( brand new i think) and the reading across MCB in OPEN i.e. OFF position I get >200meg as you would expect and CLOSED i.e. ON 0.00meg again as you would expect.
My collegue has 'tested' these MCBs i.e. tried them out and they seem to operate normally..even in OFF position there is no 'let through' of voltage as I would have expected given the 0.20meg reading
But I think the MCBs should be replaced as their integrity cannot now be guaranteed..
Has anyone come across this problem before??
Thanks for any help,
Doglog

I agree i think that all affected MCB's should be replaced.

 

[acat]

Be safe and replace them better safe than sorry



Chris

 

[Des 56]

We dont test mcbs,we have to rely on manufacturers so,
I dont think any manufacturer would take responsibility for their continued use

Doing an insulation test across an mcb may not be a good idea,continuity yes but insulation maybe not

 

[Guest123]

I would agree with Des on this.....try a low res ohmmeter and a continuity test, I/R may damage them.

For peace of mind I would replace them too.