Downlights Tripped

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Mastbruch

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Just looking for a bit of help. Just finished fitting some Downlights and they have tripped the downstairs, the wiring all look spot on yet when I tried again only 3 of the 8 lights worked.  I have a tester should I test continuity from the switch or would an IR be appropriate.

Thanks.

 
you should have already tested continuity & IR before it was energised. my guess is you failed to IR and not detected a fault, once powered up its tripped the breaker but blown fault apart which is why it now doesnt trip but only some work

id be looking for a fault at the last light that works or the first light that doesnt work

 
Start by looking for the wiring fault at either the last of the 3 working ones, or the first of the remaining non working ones.

EDIT: Beaten to it by Andy

 
Last edited by a moderator:
Do you have the required test equipment? Your previously started threads would suggest you don’t.


Yes Tony I have Kewtech MFT. I wouldnt of said I wished I would've tested them before if I didnt have a tester.

What do you mean peed off .... the bang test is NEVER recommended.

no sympathy


Agreed Fully

 
At least you have now had good experience of why the dead testing must be completed before powering up, and you will remember this in the future and it will ensure that you test correctly.  In this case there is no major damage so a good lesson learnt.

 
At least you have now had good experience of why the dead testing must be completed before powering up, and you will remember this in the future and it will ensure that you test correctly.  In this case there is no major damage so a good lesson learnt.


Defiantly Ardet lesson learned mate.

 
Just done an IR and that all went through smoothly. Got 2000 L/N 2000 L/E 2000 E/N Then I tested at individual Downlights and I am getting a reading from 0.23 from 4 of them then when pressing the switch 2000 which is fine but the other downlights just getting 2000 when pressing the switch on and off. It so much easier doing it at college yet completely different when you have to do it for real so to speak.

 
faulty mights maybe? did you zap the electronics at 500v instead of 250?
No took all bulbs out and devices unplugged and passed the IR.

I really do enjoy fault finding just a pity I am not very good at it as I cant work out why I am only getting readings on 4 of the Downlights. Might have to look at the wiring within the Downlight.

 
are they LED or halogen? if halogen then with the lamp removed you should be getting a very high IR reading between all 3 conductors. LED and you will get a very low, L-N and high L-E, N-E.

what points are you testing at?

 
You only have three lights that worked so after that third light there is a disconnection.  Because of the disconnection all readings after that in the circuit are high because there is no complete circuit.  Presumably the four lights that show a low reading were the three that had been working and the fourth is the location of the disconnection.

When testing at the downlights with the switch off all readings are high but with the switch ON the readings are low, this would indicate that the fault (between whichever conductors you are testing) is before the light switch, this is slightly odd because you had some working lights which were not tripping and often the fault would be near the disconnection.

However 0.23MΩ is not enough to trip an RCD so the fault may be only partial now.  I would therefore be checking the wiring in the switch to see if there is a damaged core almost touching the back box.

I would also look at light four and reterminate the connections.

Then re test IR to ensure the fault is clear and also at end of circuit do R1+R2 and compare with Rn + R2, they should be similar if the disconnection is cleared.  Remember on IR to test LE, NE, LN and compare readings.

 
@Andy I tested at the CU for the IR where I tested LE, NE, LN and after this test I then linked the line & earth where I tested first at the socket between the SL/CPC then my R1 and R2 at the last light.

@Ardet because they are cheapy LAP Downlights from Screwfix the terminal box was so tight to get the wires in maybe a couple have came loose.

Going to check the terminations again when I get home.

 
Ok because i did not know you were doing R1R2 or what units you were giving results in I assumed it was still IR, however the results of the R1R2 show the low readings to be connected lights high ones not connected so still check light four connections, the fault sems to have cleared but check for cable damage or loose connections.

 
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