LED Decking Lights trip RCD?

[ColinH]

I have just fitted 10 x GU10 LED (240v) decking lights (1.8w each) which i have run a spur from the garage socket via a switched fuse metalclad unit. the cable i have used to the lights is armoured cable (1.5mm) and where necessary have used weatherproof IP56 enclosures. the lights work perfectly but after about an hour, the RCD unit trips knocking off the Main RCD switch in the CU. (distance from garage to lights is about 25 mtrs) i have double checked all the connections and they are all fine? Any ideas on why this is tripping as very frustrating...

 

[Andy™]

whats IR readings?

 

[rugbymacc]

have you done any testing on the circuit ?

continuity ?

IR

 

[ColinH]

checked all the connections with standard multimeter and don't see any resistance? all appears ok?

 

[rugbymacc]

you might want to perform an Insulation Resistance test at 500 volts dc

this will show up compression or cable defects, which can cause an rcd to trip

 

[ColinH]

OK thanks, is this typical for it to work ok for an hour or so and then trip the RCD?

 

[a1spark]

Hi Col.

As andy says , you need to carry out insulation resistance tests as your next stage in tracing the problem.

a1spark

 

[ColinH]

Will do thanks!

 

[rugbymacc]

difficult question to answer ......

we really need to see the result figures to give you a more precise answer

.. could also be damp

 

[ColinH]

Will get the IR test done then update the thread! hopefully this will pinpoint the problem? I have just bypassed the SWA cable completely and wired the lights via a 3 core cable plugged into the garage socket to see if it trips the RCD. at least by process of elimination i can see if its the cable thats the problem or one of the light fittings? If not it suggests its the SWA cable from the garage but i laid this myself and it was new cable and all new IP56 junction boxes. I also silicon sealed the conduit at the base to seal any moisture from coming up from the ground.

Just for clarity, Am i ok taking a spur off the garage double socket? there is nothing else connected or other spurs? the socket was originally installed in the garage when the house was built (2000) and has its own breaker 16A on the CU

 

[Doc Hudson]

Welcome to the forum Colin, I have merged & tidied up your threads. Did you not check the insulation resistance before energising the cable?

Doc H.

 

[ColinH]

Thanks for tidying up! appreciate it..

Yes i laid the SWA cable, connected to junction box fitted on wall at the bottom of the garden. IP56. I carried out continuity test and IR test using a digital multimeter which gave clear readings at the time. I then connected the 10 GU lamps in there respective pots using the same 1.5mm SWA cable (daisy chain connection). i then carried out the same test so it should really be ok? the lights used are low energy 21 LED GU10 from TLC. i have tested them all individually and they work fine. cables are introduced through the glands at the base of the pot with rubber grommet so well sealed. they also have around 15cm beneath the lights so no water should be getting inside the fittings. incidentally, i introduced the junction box as i wish to run a second SWA cable to feed another area of the garden for a couple of LED lights under trees etc although i don't think this is relevant at the moment.

 

[Andy™]

a digital multimeter will not give you IR readings that are much use. and almost guaranteed it wont have the required 500V test voltage. and i doubt a many multimeters have the 200mA test current also required for continuity testing.

 

[steptoe]

a normal digital multimeter will be unable to generate enough voltage/current to show up any defect in the cable

 

[ColinH]

Thanks for the info on the multimeter. I'm off to buy one for the weekend!

 

[Apache]

Thanks for the info on the multimeter. I'm off to buy one for the weekend!

Have a look over on ebay and see if you can find a 2nd hand Robin one or similar. They can be had for well under

 

[SPECIAL LOCATION]

Thanks for tidying up! appreciate it..Yes i laid the SWA cable, connected to junction box fitted on wall at the bottom of the garden. IP56. I carried out continuity test and IR test using a digital multimeter which gave clear readings at the time.

Hello ColinGuinness

I am confused here:|

What exactly do you call a clear reading???

What is a "Clear" continuity reading when its at home....

Do you mean your resistance R1+R2 is the correct value appropriate to the length of the cable run?

and what are you calling a clear Insulation Resistance test reading?

Do you mean in excess of 999Megohms or just above the min acceptable 2Megohms??

remembering that for new cables an acceptable value would NOT be the min 2meg value?

Thanks for the info on the multimeter. I'm off to buy one for the weekend!

to buy a multimeter?

thought you said you had a test meter?

What about an insulation resistance tester you will need a few hundred to get anything decent!

Could I please ask are you an electrician or just training / DIY

It does sound as though you haven't actually done the basic tests for this cable prior to sticking the lectwickery on to it! :_|

How are you proceeding with getting the building regs compliance certificate?

Are you able to self certify?



Then the other question has to be..

Has the RCD been tested?

what are its trip times & current?

:|

 

[ianmacd]

If both RCD's are tripping then discrimination has not been taken into account when designing the garage circuits too.