Shock protection on luminaries

I know that other standards sometimes have different ideas about shock protection to BS 7671 (e.g. BC and ES lampholders having bare live parts). Does anyone here know what the requirements for shock protection (when basic insulation fails) for domestic wall lights - specifically the type supplied with a flex, in-line switch and plug (i.e. expected to be in-reach). I'm not sure which product standard would apply. My natural reaction was to expect them to be either earthed or marked as double insulated - but are there any other options allowed by the product standard?

As you might guess, I've been asked to fit one and it doesn't look at all right to me - steel fixing bracket seems to be exposed to wiring with just basic insulation at the back of the fitting, and is then in direct metallic contact with the dome nuts holding it all together at the front.

I didn't much like the idea that it was sold as retail but supplies as a kit of parts - flex had plug and switch fitted, but supplied with bare ends to connect to the fitting - nasty if a little one got hold of it and tried to plug it in... but that's a different issue.

          - Andy.

  • I use additional PVC sleeving and lots of insulation tape behind things like this.

    Z.

  • Yup trying to convert to double/reinforced insulation might be one option ... and if the the back of the fitting was my only worry I might go for that. One of the other worries is where the wires to the lampholder run through a hinged elbow (obviously intended to be moved repeatedly in use) - they're just two coarsely stranded fairly thin but stiff single insulated wire, (probably 7-strand and about 0.5mm² at a guess) with a bit of braided sleeving over them. I've seen the braided sleeving trick before on Class II fittings in that sort of situation, but as far as I remember it's always been over sheathed flex, not individual singles. Maybe I have an overactive imagination, but I can easily imagine one of those thin wires fracturing with repeated flexing and then a strand easily poking through the braid onto the metalwork.

    I was looking for a bit of ammunition about the actual requirements before I made too much of a fuss with the manufacturer/importer and/or deciding it I'm right risking upsetting 'er indoors by refusing to fit it.

       - Andy.

  • Yup trying to convert to double/reinforced insulation might be one option

    Only issue being, insulation + insulation does not necessarily equate to 'double or reinforced insulation', although 'insulation plus suitable mechanical protection (earthed if metallic)' may meet the requirements, such as insulated+sheathed cables.

  • it will depend how the manufacturer intends it to comply, product standards are not as simple as the wiring regs and while class 0, 0A 1, 2 etc are convenient ways to describe appliance protection levels and earthing schemes, you may have a hybrid 'platypus device' with bits that fit more than one classification in the same device, which confuses matters. (note that class 0, no reinforced insulation, no CPC, and 0A - no reinforced insulation, and CPC as independent 'tail' are not accepted on mains devices in CE/UKCA land)

    I suspect the sleeving over the singles is intended to give reinforced insulation, but if it does or not is all about how well it performs on the hi pot test, and whatever other wear tests the makers may or may not have done.

    On the past I have been know to add a CPC to turn what felt like Class 0 into 0A - still not 'legal' but feels a lot safer. There are some pretty crummy light fittings out there.

    Mike

  • use a heat sink sleeve for live and neutral cable to insulate live vire with metal part &for  protect by shock 

  • Aligned with this discussion, 18th Edition introduced Regulation 411.3.4 to require additional protection of lighting circuits in domestic installations.

  • But Andy's example involves an appliance with a 13 Amp plug. not fixed wiring.

    Z.

  • 411.3.3 then ?

    Although I would add that some of the 'permanently wired' fittings are similar.

  • Unfortunately, sleeving the wires isn't going to be particularly practical in this case - loose terminal blocks to deal with and the internal wiring goes through exposed metalwork that doesn't have enough free space to accommodate the extra thickness of the sleeving.

    So to make the best of a bad job, I've changed the flex to 3-core and managed to earth all the exposed metal parts. I don't like relying on RCDs alone for shock protection from single faults if it can be avoided. 

    Can anyone confirm if it's BS EN 60598-1 I should be looking at?

        - Andy.