# UK problem



## racerjim0 (Aug 10, 2008)

I am relaying this info from a friend in England who is looking for some answers to his electrical problems. Any significant ideas would be appreciated :


I'm trying to find out if there is a service life on Consumer unit RCCBs

Now, we run 240v 50hz in the UK. Here at Dog Towers there has been an ongoing electrical issue for at least the 7 years before I moved in.
I have uncovered several things and fixed them,
but,
I suspect that the RCCB has tripped so many times that it has become oversensitive or just plumb wore out.
Contact switches usually have a service life based on number of operations. But I can find no info to that effect on the net.

To give an example:- it will flip out several times a day, or not do it for a week. It will do it with minimal load on the system and we've never tripped an MCB.

It can be as simple as pushing a plug in a socket (appliance off) that will trip it - our sockets are switched and it will do this with the switch off, or when you flick the switch to on - even with the appliance itself in off mode. Can be any appliance. And then it wn't do it again for days.

Now, a curious part of this is that one 30amp direct feed circuit that I worked on (not ring main) has a reading of 12v on the live feed - with the MCB switched off !!!!! Flicking the MCB on provides 240v in the live feed but doesn't trip the RCD.

So, some thoughts from a suitably experienced person would be gratefully recieved - please, no half informed speculation. __________________


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## frank (Feb 6, 2007)

Opperating close to its design parrameter a RCCB will neusance trip if total residual leakage reaches 30ma level' The same will apply if the sum of loads leakage of circuits or appliances has a leakage value approaching this level too. Non of the above would occur if an MCB was subsituted. High EMF voltages are created at a switch when opperated. This can pulse an earth leakage situation especially when a RCCB is working to near capacity. 12 volts measured at the circuit as you describe is fine. This is either an internal measurment of your meter or the capacitive value of the circuit. It can also be the difference of potential measured between neutral and earth which if you are measuring at a switch live location with appliance on is the case.

Frank


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## frenchelectrican (Mar 15, 2007)

Frank did post few good answer with the UK system however maybe I can add along the way due I have see simauir situation with RCCB breakers { I know UK are little tighter on ma rating than France is } but if you have other device or any electronque switch point and any load can add up to near 30ma and trip out.

There is couple way you can do this but need proper tools to do this one is a clamp on ampmeter and read the Terra { Earth } conductor to make sure you are not actually drawing anything you may need a very senstive ampmeter to read this low a scale.

Somecase you may have intermixed ring and radial circuit it can affect the capitive coupling as well espcally with long conductor run more than 35 meters.

And I will suggest that get someone whom use the PAT or Megger to verify the system to updated to current reguations.

By the way Racerjim the RCD breaker will have serveal ma rating along the standard rating so they will have 100ma or 30ma or some RCD which we have 10ma { special item will have low as 6ma but very specfic location we can use those low rating } 

Hope that help a bit.

Merci,
Marc


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