RCBO trip, any easy way without removing CU cover to tell why?

[ericmark]

I hear no splash when resetting, so assume an imbalance fault. But is there a way without removing cover to know if overload or imbalance fault? Fusebox Type AC RCBO fitted, although it said type B on the box.

Looks like a get the insulation tester out job, but looking for easy route first.

 

[JohnW2]

I hear no splash when resetting, so assume an imbalance fault.

"Splash" ?

But is there a way without removing cover to know if overload or imbalance fault? Fusebox Type AC RCBO fitted, although it said type B on the box.

As I've always said, one (small) downside of standard RCBOs is that when they trip, one does not know whether that was (assuming a 'legitimate' trip) due to over-current or residual current - so fault-finding can be a little less straightforward than when the OPD and RCD for the circuit are separate.

Having said that, I would suggest that devices (OPDs or RCBOs) tripping because of overload or L-N faults is pretty rare, so if an RCBO trips, it is very probably due to residual current (or 'for no apparent reason',such as you seem to sometimes experience!).

 

[ericmark]

Found, the darn dishwasher, socket under the sink, I missed it when trying to disconnect all, not put the insulation tester on it yet, but once unplugged all worked again.

"Splash" ?

I would expect to hear some arc splash if the trip was an overload, to trip a B32 that's 160 amps, so a fair current to trip it within less than a second.

Checked after power restored. Ramp test 22.5 mA, before resetting RCBO after so it seems some leakage on the other 13 RCBOs, but not too worried about that leakage, but when my son is here, seems prudent to do some more tests.

Just glad the freezers were on an UPS so no time pressure to find the fault. Since the dishwasher was not running, seems likely a neutral - earth fault.

 

[JohnW2]

Found, the darn dishwasher, socket under the sink, I missed it when trying to disconnect all, not put the insulation tester on it yet, but once unplugged all worked again.

Well found!

I would expect to hear some arc splash if the trip was an overload, to trip a B32 that's 160 amps, so a fair current to trip it within less than a second.

Yes, I would expect an arc. It was the word "splash" I wasn't familiar with being used in this context!

Checked after power restored. Ramp test <...> 22.5 mA, before resetting RCBO <...> after <...> so it seems some leakage on the other 13 RCBOs ....

I don't fully understand what you are saying here. Don't forget that a 30 mA RCD (RCCB or RCBO) may operate with residual currents as low as 15 mA, so a ramp test result between 15 mA and 30 mA does not necessarily mean that there is any 'leakage' on the circuit.

 

[Harry Bloomfield]

"Splash" ?

I would interpret that as, an obvious larger current flowing through the contacts, enough to trip it. The difference between an RCBO tripping on current overload, versus earth leakage, is quite subtle, not well defined sometimes. On current trip, the release tends to be much noisier/sharper/more defined. On earth leakage trips, the trip is usually more gentle.

 

[ericmark]

Now it's the going around plugging the doorbell, cordless telephone, etc. Back in.

 

[JohnW2]

I would interpret that as, an obvious larger current flowing through the contacts, enough to trip it.

Indeed - but, as I just wrote to eric, I raised the question because I have never heard the word "splash" used in that context - have you?

 

[Harry Bloomfield]

Indeed - but, as I just wrote to eric, I raised the question because I have never heard the word "splash" used in that context - have you?

Yes, but a long time ago - usually applied to hot, flying copper as a result of a fault.

 

[SUNRAY]

Indeed - but, as I just wrote to eric, I raised the question because I have never heard the word "splash" used in that context - have you?

Yeah an elderly term from when new fuses blew as soon as the carrier was pushed back in.


Not that that ever happened to anyone though

 

[SUNRAY]

Found, the darn dishwasher, socket under the sink, I missed it when trying to disconnect all, not put the insulation tester on it yet, but once unplugged all worked again.

I would expect to hear some arc splash if the trip was an overload, to trip a B32 that's 160 amps, so a fair current to trip it within less than a second.

Checked after power restored. Ramp test View attachment 381624 22.5 mA, before resetting RCBO View attachment 381625 after View attachment 381626 so it seems some leakage on the other 13 RCBOs, but not too worried about that leakage, but when my son is here, seems prudent to do some more tests.

Just glad the freezers were on an UPS so no time pressure to find the fault. Since the dishwasher was not running, seems likely a neutral - earth fault.

That'll be the DW mains filter then.

 

[JohnW2]

That'll be the DW mains filter then.

Quite possibly -although, of course, it's not unknown for DW electrics to become 'full of water'

 

[ericmark]

Second time problem with dishwasher in 4 years, a Blomberg, so repair or renew is the question, around £100 to get it repaired, £430 for same as we have, although I would not do that. Our first dishwasher lasted around 25 years, so this is dishwasher wise quite new.

But the game has moved on, with delayed start to use off-peak etc. So seems I am to be dragged around show rooms tomorrow.

 

[JohnW2]

Second time problem with dishwasher in 4 years, a Blomberg, so repair or renew is the question, around £100 to get it repaired, £430 for same as we have, although I would not do that.

Have you ascertained what is wrong with it?

 

[ericmark]

Have you ascertained what is wrong with it?

No, but once there is a track, to stop it happening again, it will likely need a new part. It was not running when it failed, so assume a neutral - earth fault. Getting down on my knees, I need help to get back up again, so not keen on DIY repair.

 

[JohnW2]

No, but once there is a track, to stop it happening again, it will likely need a new part. It was not running when it failed, so assume a neutral - earth fault.

As Sunray said, one of the mains 'filter'capacitors would probably be the most likely culprit, and a replacement component would probably only cost 'pence',but there is obviously the issue of fitting it.

Getting down on my knees, I need help to get back up again, so not keen on DIY repair.

I know the feeling/problem, so can both identify and sympathise with that!