Freezer tripping electrics?

victor2

Having experienced a similar problem due to some failed wiring, I pondered the idea of going from a single RCD to RCBOs, but it would involve an entirely new (read expensive) CU. Plus, I realised you'd still have one switch protecting the entire ring main, so tracking down the problem wouldn't be much easier.

Section62

ka7e said:

2 lady sparks visited today and have replaced a 16amp thing with a 32amp one on the kitchen/garage circuit. Fingers crossed that this works...

That sounds a bit... unusual.

An RCD shouldn't be tripping because a MCB (?) was rated too low.  And if a previous electrician (presumably during the rewire 6 years ago) fitted a 16A MCB for the circuit then hopefully the latest electricians carried out a full review of the circuit and the necessary calculations before swapping it for a 32A one.

Did they do insulation resistance checks... do you know what values they got for the problematic circuit?

WIAWSNB

Yup, based on what we've been told, it doesn't quite add up.
Fingers crossed, tho'.

bjorn_toby_wilde

Section62 said:

ka7e said:

2 lady sparks visited today and have replaced a 16amp thing with a 32amp one on the kitchen/garage circuit. Fingers crossed that this works...

That sounds a bit... unusual.

An RCD shouldn't be tripping because a MCB (?) was rated too low.  And if a previous electrician (presumably during the rewire 6 years ago) fitted a 16A MCB for the circuit then hopefully the latest electricians carried out a full review of the circuit and the necessary calculations before swapping it for a 32A one.

Did they do insulation resistance checks... do you know what values they got for the problematic circuit?

Mmmm. I saw the list of items on that circuit in an earlier post and there was quite a list, including an electric shower. Maybe it’s also worth considering that the earlier electrician may not have specified the circuit correctly.

ka7e

Section62 said:

ka7e said:

2 lady sparks visited today and have replaced a 16amp thing with a 32amp one on the kitchen/garage circuit. Fingers crossed that this works...

That sounds a bit... unusual.

An RCD shouldn't be tripping because a MCB (?) was rated too low.  And if a previous electrician (presumably during the rewire 6 years ago) fitted a 16A MCB for the circuit then hopefully the latest electricians carried out a full review of the circuit and the necessary calculations before swapping it for a 32A one.

Did they do insulation resistance checks... do you know what values they got for the problematic circuit?

She tested some of the wires in the CU, the shower etc. Unplugged everything and tested again. I have 41 sockets on the circuit and most of them have something plugged in, if that's relevant. After upgrading the CU she tested a socket in the kitchen 3 times until it forced a trip and seemed happy with the result. They were a bit nonplussed by the timing, ruled out the CH as it's off until 8am, turned off the solar inverter and that came back on with no issues. I know it trips after 6.30am and the only time I've witnessed it actually trip, it happened at 7.30. Checking my Octo-Aid app, 7.30 is when it records usage dropping out, too.

WIAWSNB

RCD 'nuisance' trips are notoriously hard to pin down.
Fingers crossed it has been sorted, just as mine evidently self-sorted a few months later.
I was on the verge of replacing my CU with one with individual RCBOs, and when I check these out now, they are not expensive - around £100 will seemingly buy one. 
Not all circuits need to be on their own RCBO - the lighting circuits could, for example, still be run from a single RCD in a split box, supplying a few MCBs.
That's my understanding, at least.
As mentioned by another poster, RCDs typically trip at 30mA. The issue is that virtually all circuits will have a tiny inherent 'leak' or imbalance of a few mA, so these all effectively add up so could be 'safely' hovering at just below the trip level for much of the time. It'll then just take a momentary wee 'spike' to send it over the top. Now, trace that spike! Noooop.

ka7e

Well, it tripped again this morning.  It didn't trip yesterday and the only things I'd plugged in since then were washing machine, tumble dryer and air fryer.

Scrounger

Time to call the two ladies back.


Scrounger

Section62

Scrounger said:

Time to call the two ladies back.

maybe, if they will come back and fix the problem with no further charge.

But if they will want paying for a second visit then I fear if they thought the problem would be fixed by swapping a MCB for a higher rated one then ka7e's bill is going to get very large before the tripping goes away.

Maybe a second opinion would be worth the risk of some additional expense, to avoid a much larger one.

Scrounger

ka7e said:

2 lady sparks visited today ... 

I had a bad feeling about this even before I learned of their 'solution'.  


Scrounger