strange fault

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wattsup

Strange fault.
Rewire, 8 circuits all rcbo protected
Tests out ok
Intermittent fault
Turn basement lights off at switch (fed via a 6a rcbo)

basement power trips? (on an adjacent 16a rcbo)
no crossed neutrals.

The 16a rcbo trips when turning lights off not on?
Any ideas, never seen this type of fault before.

Impossible ? you would think, or i would
 
a dodgy connection somewhere could be the cause. any chance there is a shared neutral somewhere on the installation, or even a polarity reversal?
 
I have come across very similar problem due to rcbos all together and one was affecting the other just by being next to it, forget offhand which make of rcbo it was but think it may have been hager? Was a good while ago and was feeding server units/racking system. Not encoutered same problem since though.
 
BigBreakfast said:
I have come across very similar problem due to rcbos all together and one was affecting the other just by being next to it, forget offhand which make of rcbo it was but think it may have been hager? Was a good while ago and was feeding server units/racking system. Not encoutered same problem since though.
Click to expand...
so that could be something similar to an induced voltage affecting adjacent RCBO? clutching at an ethereal straw here! LOL.
 
What light has been fitted in the basement?

Had a fault before whenever i turned the kitchen flourescent off it would trip the RCD
bit of a strange one, but narrowed it down to the neutrals being loose in the fitting
 
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Thanks for the quick replies, no weed!
Basement lighting has 3 fluros, and one pir flood.
Basement power has one twin socket, and CH boiler.

I thought maybe dodgy connection, but then thought that should trip the rcbo circuit concerned.

no reversed polarity. Brand new installation, I have rewired, so scratching head not appropriate.

Proteus board,rcbo's. Swapped rcbo, same happens.

Doesn't always trip, but fairly regular...soon as I switch basement lights off, basement power trips...def. something to do with basement light circuit. I'm thinking some crazy induction type thingy. Never seen it before, so I have to scratch head in secret..away from client
 
Try loose neutrals in one of the flourescents, had a almost identical fault a few months back

Proteus board doesnt say much for you though, what were you thinking fitting that ****e ! haha
 
You could try swapping RCBOs around so that the two in question are not adjacent (pref at opposite ends of the board). That might confirm or eliminate the theory of RCBOs influencing each other.
 
Out of interest,does the proteus rcbos have a earth tail


If there are
Here is my stab in the dark

I believe the rcbos with the earth tail are more electronic rather than mechanical and the earth tail monitors the voltage between neutral and earth

The fluorescent lights may produce a back emf when the choke magnetic field collapses when switched off
This may cause induction into the cpc which unsettles the other rcbos electronics

Maybe cables running alongside the chokes causing the problem

If there are earth tails,try disconnecting them to see if they stay in
 
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Yes des, they do have earth tails. I did disconnect tail on lighting rcbo..(similar thoughts to you)...now just realised I should have disconnected the tail on the 16a rcbo... Try that tomoz and or move rcbo to other end of board....see what happens (yes proteus are a pain) no room and crap screws, but i would expect them to be ok electronically
 
nothing wrong with proteus boards... in a skip.
 
If your lighting cct is not tripping when you switch off the basement lights and only the 16 A RCBO trips out my money is on that one being faulty in some internal way IMO.

Have you tried replacing the 16A one for another to see if the problem replicates its self.

As you have stated the RCBO should be electronically OK but with lots of things these days you are now the quality control person but don't get paid for it.

Hope you get to the bottom of it!!
 
Be intresting on discon flyleads !
good luck buddy when you do find the fault please post on my Tell us your faults thread.
Regards
Kung.
 
Update
First off, it is a protek board / rcbo's, not proteus as I first said. Don't know why I said proteus
Anyhow, tried the easy bits first, no loose neutrals etc
Disconnected rcbo earth tails, still trips basement power.
Last resort, which I knew would be pain, move rcbo basement 16a rcbo to far end of board
At first I thought fixed, no trip, went into overdrive on off on off basement lights, tried it 20 times or more, customer at side of me, no trip.
Right fixed!
Err no, packed tools up, turned basement lights off, friggin downstairs ring main tripped.
The actual basement lights never trip, always other rcbo.
As I said before, the basement lighting circuit is 3 fluros and one pir flood only, I can actually physically see and trace cables, no damage, all connections secure blah de blah..
Please remember, trip only happen when switching off lights, not on.
Headache, I'm going to fit a new board, Crabtree Wylex or MEM I asked the customer to get, (I didn't supply anything) see what happens...
Lost me this one
 
how are the flouros wired? i presume 3 plate then a loop off to others? try disconnecting the loop to rule out dodgy fittings etc..

But going back to my fault previous the loose neutrals in the flourescent fitting caused other rcbo's to trip whenever i turned the light OFF,
 
In case it is induced by the neighbouring MCB, have you got space to put a blank between them? Or move them around the board? Just to test out the theory, be interesting to hear if it cures it.

PJ
 
Its the switching off, that causes the trip. No, not three plate, neutrals connected thru at switch boxes.

I can't get my head round to the 'off' that causes other rcbo to trip. If rcd then maybe dodgy ne fault, but not rcbo's. Each rcbo should be a dedicated circuit?
 
no ne fault, my first thought btw. In any case if ne fault it would/should trip the relevant rcbo...I would think? and the fault would be there whatever ...only trips when switch off basement lights.
 
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Make sure that if the l/n terminals have a resistor across them that all the fittings that supposed to have them do have them.

We had a fitting that was doing the exact same thing, it was missing its resistor that it normally had. Replaced that and the rcd didn't trip anymore.
 
Make sure that if the l/n terminals have a resistor across them

Ahh, I do know one fitting has the supressor for sure.....I'll check the others on monday, good call, hope you are right,,,clutching at anything right now
 
I'd agree with des56. and OldeSparky
unbalanced Neutral earth voltages, however they are caused, can produce nuisance tripping on other unrelated RCBOs. Its usually caused at the point of switching both on and off.
 
Do you have any items plugged into the 16amp circuit that trips out? if so what are they.

Its really is a brain teaser this one..., Have you done a full IR test? Might be worth doing it again
Are you sure you got L&N connected correctly in the fittings including PIR?
Check you have the same L&N out the RCD for all ccts?
Is the neutral bar correcly connected.

Any chance of getting a pic so we can all have a look of the DB?
 
Tested again, same 'good results'...so changed board to wylex. Problem fixed!

Another ...kin 6 hours testing retesting, scratching head, but some relief at last...beware of protek rcbos
 
I've been following the thread with interest. Glad to hear it's been resolved, mate. The old adage of buy cheap, pay twice comes to mind. It's just a shame the customer cant ever see this!
 
The Great Lord Proteus strikes again.
Complete and utter CEF rubbish, another example of whats wrong with the bloody industry. How on earth are these companies in business peddling such rubbish:mad:.
 
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wattsup said:
Tested again, same 'good results'...so changed board to wylex. Problem fixed!

Another ...kin 6 hours testing retesting, scratching head, but some relief at last...beware of protek rcbos
Click to expand...
Thanks for the update, been thinking bout this fault lots, thank god its fixed
 
just come to light tonight...
A year or so ago there was a 'bad batch' of protec rcd's/rcbo's.
Anyhow the manager of the wholesaler (small independant shop) vowed never to stock protec ever again, sick of callouts and exchanging cu's for contractors who had bought.

The supplier gave assurances the problem was fixed, so he bought in again at a very cheap price...sweetener. All has been well apparently for the past 12 months or so. Until now!
 

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