strange fault

[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

 

[telectrix]

a dodgy connection somewhere could be the cause. any chance there is a shared neutral somewhere on the installation, or even a polarity reversal?

 

[BigBreakfast]

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.

 

[telectrix]

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.

so that could be something similar to an induced voltage affecting adjacent RCBO? clutching at an ethereal straw here! LOL.

 

[Amp David]

Have you rewired it of has it been done previously and you're there for the fault?

 

[vernam616]

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

 

[telectrix]

mmm basement, lights, weed growing.

 

[wattsup]

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

 

[vernam616]

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

 

[wattsup]

Proteus board doesnt say much for you though, what were you thinking fitting that ****e ! haha
'labour only'

 

[HandySparks]

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.

 

[GLENNSPARK]

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 can stoop lower than that lol...."chintz"....

 

[vernam616]

you can stoop lower than that lol...."chintz"....

Haha good point, forgotton all about them fabulous d/b's

 

[Des 56]

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

 

[wattsup]

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

 

[vernam616]

Im intrigued now, please update the thread when you find out!

 

[BigBreakfast]

so that could be something similar to an induced voltage affecting adjacent RCBO? clutching at an ethereal straw here! LOL.

Well that was one of my thoughts too, in the end I think I swapped out a couple of rcbos and the problem never appeared again?

 

[telectrix]

nothing wrong with proteus boards... in a skip.

 

[tony mc]

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!!

 

[OldeSparky]

earth neutral fault on other circuit...