Lights tripping

[GaryCharlesworth]

Hi..I have 3 20w outside led spots connected to 6A RCD..there is a fault somewhere which i haven't looked for but the 6A doesn't trip, its the 63A that trips..any ideas

 

[opps]

63A?

And when you say the 6A Rcd, do you mean a 6Amp fused spur unit?

If the lighting is ultimately supplied via a RCD in the consumer unit, there may be water in one of the fittings. In such as case, the RCD will trip, and not neccessarilly one of the MCBs.

I am not an electrician, a photo of your consumer unit (pointing out the bit that trips) will help proper electricians to advise you further.

 

[Harry Bloomfield]

63A?

Sounds like a single RCD, protecting several circuits, or perhaps the entire CU.

 

[Harry Bloomfield]

Sounds like a single RCD, protecting several circuits, or perhaps the entire CU.

All the OP can do, is disconnect the middle of the run of lights, then see if it trips - if it does it's a fault on the still connected light(s), if not the problem is on the section disconnected.

 

[opps]

Sounds like a single RCD, protecting several circuits, or perhaps the entire CU.

Agreed.

Sorry, I was editing my post when you replied.

 

[GaryCharlesworth]

Sorry MCB doesnt trip.the 63A does

 

[Harry Bloomfield]

That's a B6 a 6amp MCB ??

 

[GaryCharlesworth]

Yep..it doesn't trip..the36 A main one does which feeds other things

 

[securespark]

When you say 36, do you mean 63?

Can you post a pic here of the tripping device?

I suspect it is an RCD. In which case, there will probably be a fault sending current down to earth somewhere.

Maybe a damaged cable?

The previous advice is good. Split the circuit and go from there.

 

[GaryCharlesworth]

Thanks..I know there is a fault ive yet to find.but why doesn't this 6A mcb trip out..I'll change it for a new one

 

[pcaouolte]

The 6A MCB would trip when the circuit is drawing more than 6 amps, this is very unlikely on a lighting circuit unless the live wire is touching neutral or earth. Don't waste your time changing it, there is almost certainly nothing wrong with it.

The RCD which is tripping detects a fault between live and earth or neutral and earth and disconnects the circuit very quickly. It is likely that you have water in an outside light or a damaged cable. These faults would be expected to trip the RCD. Once the RCD has tripped there is no current available to trip the MCB so it doesn't trip.

Follow the advice above to disconnect the lights at various points along the circuit until you find the faulty part.

 

[JohnD]

Hi..I have 3 20w outside led spots connected to 6A RCD..there is a fault somewhere which i haven't looked for but the 6A doesn't trip, its the 63A that trips..any ideas

Yes, I know exactly what it is.

So do the others.

Post a photo of your 63A device and your 6A device and I will explain the difference.

BTW a stock photo from a catalogue is useless. We need to see your own photos from your own installation.

 

[ericmark]

This should help identify what trips, there are three tools, the RCD tester tests the RCD but it is unlikely to be faulty, the clamp on can test when live, and the insulation tester when dead both testers cost around £35 each but they also need some skill to use them. So the start point is look for water ingress. This is most likely cause, the problem is the insulation tester used 500 volt DC and the house uses AC and the clamp on will only work when it has not tripped.

AC current will always have some capacitive and inductive leaking, so there is a limit to how much can go through a single RCD, so a 30 mA RCD will trip between 15 and 30 mA most likely around 26 mA and up to 9 mA is allowed with AC linking so you have in real terms between 6 and 16 mA before it trips with a installation near the limit.

With RCBO's we are looking at a larger fault before they trip as less background leakage. And when they do trip we loose less, but they cost more than MCB's so once over a 4 circuit consumer unit is fitted you can save money by having multi MCB's on one RCD, with my 14 way board could save £150 but I feel that is nothing to the loss if one freezer defrosts. But when done on the cheap, one must expect them to trip every so often.

The problem is when the leakage is from the neutral to earth, as this will increase with load, and makes fault finding harder. But seems likely simply due to water and a small drain hole will likely cure the problem.

 

[EFLImpudence]

...

 

[EFLImpudence]

This should help identify what trips,

It should but will it?

However the RCBO (Residual Current Circuit Breaker with Overload protection) is also an RCD (Residual Current Device) and the item marked RCD ( is actually a RCCB (Residual Current Circuit Breaker (without Overload protection)) which is also an RCD (Residual Current Device).