Low Voltage Lighting



For the purposes of insulation tests, could someone please confirm that standard 12v 'low voltage lighting' is classed as SELV and should therefore be tested using a 250v test voltage.

Many thanks

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27 Jan 2008
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Llanfair Caereinion, Nr Welshpool
United Kingdom
Low voltage = 50 - 1000vac
Extra low voltage up to 50vac
If extra low voltage and low voltage are both in same trunking then both are tested to same installation standard for 230vac test at 500v.
However if not in same trunking then no need to test with installation tester.


Thanks for your replies..........

I guess by same trunking were taking on the same circuit? If so, yes they are 12v downlights in the kitchen and, on the same downstairs lighting circuit as the other 240v lights. Having replaced two pendants in the lounge, I need to do an insulation resistance test for the minor works certificate. So, would the downlights be classed as just ELV and tested at 500v or SELV and tested at 250v?

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Thanks for your replies..........

I guess by same trunking were taking on the same circuit?

No. It means that if 12v and 240v are contained if the same trunking, the 12v cable needs to be tested as 240v due to the transfer of voltage across adjacent cables.

If it's on the same circuit but the cables are not running adjacent to each other then you do not need to test the 12v cables.

The normal procedure is to disconnect the downlight transformers from the circuit and then test the LV cable at 250v and then 500v. Then you can do your R1+R2 tests on the same cable.

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