Shower tripping problem RCBO

[gazdkw82]

If it fits I could wire it into my board at home as I have a few spare ways. Then I can test it properly.

 

[telectrix]

how are you going to overload it and check tripping time of the MCB? bin it.

 

[gazdkw82]

I just wanted to be sure it's faulty and I'm not missing something

 

[telectrix]

if you've replaced it and the replacement works, then it's obvious that it's a goner. either the MCB or the RCD side.

 

[gazdkw82]

Yeh I see what you mean but, it's gone from a tripping rcbo to a mcb so could it be that there is a leakage somewhere?

 

[telectrix]

there is a leakage somewhere

another chance to blame wet-pants then?

 

[gazdkw82]

So my fear is that I put another rcbo in and it trips just like before. That would mean that there is a leakage somewhere within the cable? However why is it not tripping when the shower is on but not operating? If there was a leakage in the cable it would tripped as soon as power was applied to the pull cord and through to the shower, regardless of the shower pulling water or not?

 

[telectrix]

it's most likely that the MCB part of the RCBO is at fault. every time a high load like a shower is switched on, some stress is put on the component parts of the breaker. eventually this can lead to breakdown, especially when the breaker is running close to it;s rating.

 

[gazdkw82]

Well it's a 32A rcbo and the shower is 37A so it's been running over it's rating for some time

 

[telectrix]

that's probably your answer then. if i drove my 13 year old van (186,000 on the clock) at 100mph all day, it would not last long.

 

[gazdkw82]

What test could have been done to prove this? PSC? PFC?

 

[telectrix]

you need specialist gear to test a MCB properly.

 

[hightower]

Gaz, unless I'm missing something it seems to me that you haven't even done an IR on the circuit, but you've been back it seems. I'd have given the circuit a full test before even suggesting a new shower - start at the start mate, fault finding is a linear procedure

 

[gazdkw82]

True. I wish I had done it in that way from the start. Lesson learnt

 

[telectrix]

yeras ago, when split CUs first came out ( that's them with 1 RCD covering socket circuits and the lighting etc not on RCD), i made the mistake of connecting the N of a shower feed onto the wrong N bar. RCD tripped as soon as shower was switched on. i was certain it was a faulty shower until i'd had a couple of pints and the brain re-engaged.