Light fitting not earthed ok?

Many of the most recent metal light fittings we have bought fixed to the ceiling joist with a c- shaped metal strap that takes fixing screws through the fitting. In most cases the earthing has been on that strap, if not present it is easy enough to crimp an eye on the earth lead and either pop-rivet or attach with a self-tapping screw.

Richard

is there a Class I or Class II symbol anywhere?

I'd go the mile to earth it, but on Habitat's defence, perhaps there should be a double insulated logo somewhere on a sticker that also mentions the max wattage of the bulb?

Does it have a double insulated symbol or say it's Class II?

Theo

As John Ward's video points out, adding an earth to something that's Class II (double insulated) can make things worse if there's a risk of it providing a route to earth from some other live source (eg another faulty appliance).

This rather depends on where it's going to be mounted. If it's a ceiling light on a 3m high ceiling it's rather less likely to be touched compared with a wall lamp. In the former case the earth is only protecting from something breaching the double insulation, something which is fairly unlikely in any case.

Theo

Hi All,

Yes it does have the class II symbol (one square inside another) on the box so assume it is ok then. Looking at the link above it seems it needs 2 barriers between the live and the user. The light fitting had screw down connectors inside a plastic box so assume it is that which makes it class II. For the sake of adding an earth connector seems like the added safety would be worth manufacturing it in.

Thanks for your help all

Lee.

With a class II appliance, adding an earth could be argued actually reduces safety. Since the chances of it becoming live due to an internal fault are exceedingly low, all that adding an earth will do is introduces another extraneous conductive path into the room its installed in. Hence raising the risk of shock injury from an unrelated appliance made live by a fault.

I have seen the same with no-name LED panel lights where a 20cm diameter circular metal plate is bolted to the ceiling. This contains a mains to low voltage power supply (driver), which may be double insulated, BUT also bolted to the plate is a chock block for mains connection. It would be easy for a lose strand of wire or an over long stripped back wire to touch the plate when attaching the mains to the chock block.

I have modified these fittings to attach bolted through earthing tag, plus wire, to the plate and to replace the two way chock block with a better quality 3 way version.

The metal plate also has the LEDs attached and acts as a large heat-sink.

Yes, I've seen this sort of thing as well, those glass globe fittings which have a metal base with a holder on it, and several little screw in studs to hold the lip of the glass. Looking at them they do have a lot of insulation from the metal though, so maybe that is why they do not consider it, but I suppose any kind of connection could be used. I'd never buy a cheap version of a glass globe fitting, since their plastic cracks eventually and the glass smashes on the floor., or on anyone standing underneath at the time! Brian

Yes but on many double insulated devices, on can get a humming tingling feel in the finger as you touch it, and many people feel that is not safe, even though we all know its just a function of the electrostatic field in the cable. Brian

Touch sensitive table lamps certainly so, as that is how they work - by passing a small current through your body. (I had one which would dimly light a neon screwdriver.)

On Sun, 28 Mar 2021 05:30:33 -0700 (PDT), " snipped-for-privacy@yahoo.co.uk" snipped-for-privacy@yahoo.co.uk> wrote: [snip]

As an aside, the two screws on the lightswitch here must be earthed (to the steel back-box) since if you touch them you get electrostatic effect. Is this normal?

In dry weather it's probably static discharge from you and your clothes. Time to give up wearing nylon socks and perhaps change the carpet.

Backboxes are supposed to be earthed because a wire could come adrift and make the backbox live, which would be transmitted through to the screws which someone could touch. If you have a lot of static charge then you will likely discharge yourself through the screws.

It's possible to get plastic screw covers:

Theo