Ceiling Light - No Earth ?

cheif kaiser

Hi All,

I'm in the process of fitting a new ceiling light which is metal and needs to be earthed, however when I took down the old fitting I only have a live and neutral coming out of the ceiling. The old light fitting was also metal and seems to be earthed to itself!?!?! Can I do this with the new fitting and if so how?

brightspark

You need to get an earth wire installed, or else purchase a light fitting that doesn't require an earth. You can't 'earth it to itself'. Whilst it may appear a simple job, you need to ensure continuity so it wouldn't be easy to advise you on how to do it.

Many houses don't have an earth wire fitted to light fittings, I think it only became a regulation in 1985 to earth downstairs fittings.

cheif kaiser

The old light fitting is earthed to itself and was manufactured that way and I have seen metal lamps done this way i.e the earth wire is connected to a small screw on the side of the fitting? The bracket from the new light fitting has a small hole in the centre which I think is specifically for this purpose like here http://homeguides.sfgate.com/install-ceiling-light-place-ground-wire-73590.html. Why then is that incorrect? I can't rewire the house for a light fitting!

tomdempsey200

any new points require an earth when wired..

but as you say you may not want to add a cpc(earth) when replacing a fitting.....so there's a good selection of fittings indoor and outdoor that are suitable where there's no earth present

cheif kaiser

[QUOTE.so there's a good selection of fittings indoor and outdoor that are suitable where there's no earth present[/QUOTE]

Not really helpful! I know there are many fittings available but that is not an option, the ceiling fitting matches other fittings in the room and is the last to be fitted.

brightspark

cheif kaiser wrote: »

The old light fitting is earthed to itself and was manufactured that way and I have seen metal lamps done this way i.e the earth wire is connected to a small screw on the side of the fitting? The bracket from the new light fitting has a small hole in the centre which I think is specifically for this purpose like here http://homeguides.sfgate.com/install-ceiling-light-place-ground-wire-73590.html. Why then is that incorrect? I can't rewire the house for a light fitting!

Do you live in the USA? I'm not familiar with their rules, but you can't do it here!
I doubt if it is really permitted over there either, his connecting the ground wire to the bracket serves no function other than a convenient way of tidying up the cable end. In the event of a fault developing the metal parts of the lamp in the USA would be at a potential of 55V, maybe not fatal, but a shock like that would certainly cause a fall, which might be!

As I said some fittings don't require earthing, but metal fittings generally do unless specifically stated otherwise. If you are not prepared to get an earth wire installed then purchase a DOUBLE INSULATED light fitting.

A fault developing in the fitting here would mean the metal parts of the fitting could potentially be at mains voltage 230V, enough to kill you or a family member if you touched it.

cheif kaiser

I understand why a light fitting needs to be earthed, I just can't understand why some light fittings are earthed to themselves by the manufacturer yet you say this is wrong?

Old light fitting.... earthed to itself and I also have 2 metal lamps in my sitting room that are also earthed to an earth screw?

tomdempsey200

the fitting isn't earthed to itself


that's a flexible earth connection between the two metal parts of the fitting ...a supply earth(cpc) is still required

disregard the video in the link...it's not relevant here

tomdempsey200

brightspark wrote: »

In the event of a fault developing the metal parts of the lamp in the USA would be at a potential of 55V,

http://en.wikipedia.org/wiki/Split-phase_electric_power

i think it's 120 potential fault voltage unlike the 110 site supply here where you'd have 55v

that video doesn't seem right:eek:..i've a few pints on me so it gets confusing:)

brightspark

tomdempsey200 wrote: »

http://en.wikipedia.org/wiki/Split-phase_electric_power

i think it's 120 potential fault voltage unlike the 110 site supply here where you'd have 55v

that video doesn't seem right..i've a few pints on me so it gets confusing:)

On reflection you are probably right

Just as well I don't live in the USA. :eek:

Perhaps they are trying to reduce the population.

cheif kaiser

tomdempsey200 wrote: »

the fitting isn't earthed to itself

that's a flexible earth connection between the two metal parts of the fitting ...a supply earth(cpc) is still required

That doesn't make any sense? The earth wire coming from the fitting is looped into a screw leaving only the live and neutral to connect so how and where would one connect another earth wire, there is no other earth wire coming from the fitting?

tommy2bad

Perhaps that fitting is earthed by the actual fitting screwing to an already earthed fitting in situ on the ceiling.
In which case the earth is being grounded to one side of the complete fitting which attaches to the other half which is where the rest of the earth runs back from. Just guessing, I'm not an electrician and don't recommend trusting my guess work.

cheif kaiser

Perhaps that fitting is earthed by the actual fitting screwing to an already earthed fitting in situ on the ceiling.
In which case the earth is being grounded to one side of the complete fitting which attaches to the other half which is where the rest of the earth runs

Would still require me to have a further earth wire running from the fitting to connect?!

SpaceTime

brightspark wrote: »

Do you live in the USA? I'm not familiar with their rules, but you can't do it here!
I doubt if it is really permitted over there either, his connecting the ground wire to the bracket serves no function other than a convenient way of tidying up the cable end. In the event of a fault developing the metal parts of the lamp in the USA would be at a potential of 55V, maybe not fatal, but a shock like that would certainly cause a fall, which might be!

As I said some fittings don't require earthing, but metal fittings generally do unless specifically stated otherwise. If you are not prepared to get an earth wire installed then purchase a DOUBLE INSULATED light fitting.

A fault developing in the fitting here would mean the metal parts of the fitting could potentially be at mains voltage 230V, enough to kill you or a family member if you touched it.

Some parts of the USA used metal ducts a bit like shower hoses on the wiring because there's a constant fear of fire. This is because of the low voltage (120V) used (higher amperage) and more risk of overloading and because the construction they use i.e. wooden frame buildings are highly flammable relative to our type of construction.

Americans have always been very, very tough on fire regulations because of that kind of construction. That's why you've things like arc fault detectors in new wiring there and why they've always been paranoid about fire extinguishers and smoke detectors much more so than we are.

So, it was possible in some old wiring systems there to use the duct and box as an alternative earth.

That is absolutely not the case in Ireland. The box is most likely plastic and in older wiring the light fitting boxes are generally not earthed. So, you'd have to run a new earth connection to the fitting.

Also, bear in mind that light circuits are generally not RCD protected so you can get a serious and deadly 230V shock from them which will not trip out the RCD.

cheif kaiser

Still not explain why my previous fitting had a loop earth which connected to the light fitting itself? All I am really getting are guesses but there has to be a reason why some light fittings are earthed to themselves.

eggy81

Yes you need an earth cable at the light. There is no route for fault current to travel to earth otherwise. The cable that you add should connect to that existing earth and the body of the fitting somehow. If you don't have an earth cable at it it's not earthed.

SpaceTime

cheif kaiser wrote: »

Still not explain why my previous fitting had a loop earth which connected to the light fitting itself? All I am really getting are guesses but there has to be a reason why some light fittings are earthed to themselves.

If this is the American situation. It is possible the box behind the light is earthed. It's also possible whoever installed it had no idea what they were doing and just connected an earth wire to a random earth terminal on the light.

You can't earth something to itself. It has to be connected to an actual protective earth which is connected to ground rods and usually the ESB's grounded neutral at the meter.

If there's no earth at the fitting, any fault that makes the metal surface of the fitting live will not blow a fuse or breaker and will deliver a potentially deadly shock when someone touches it.

The idea of an earth is that it makes it impossible for the exposed metal parts of the appliance or light fitting to have any voltage greater than 0V by providing a high quality, easy path to earth via the wiring.

It means that if a fault occurs like a live wire touching the metal casing that a large current will flow through the earth causing the fuse to blow or the MCB to trip.

It also protects you by ensuring that no metal surface can become live and cause a current to flow though you when you touch it.

In Irish's wiring you also connect all the plumbing and other metal surfaces to the earthing system so that everything is at the same potential and there's no potential difference (voltage) between any two metal surfaces. This eliminates risk of electric shock.

Sir Arthur Daley

cheif kaiser wrote: »

Still not explain why my previous fitting had a loop earth which connected to the light fitting itself? All I am really getting are guesses but there has to be a reason why some light fittings are earthed to themselves.

The loop that you are describing is the earth wire that is earthing other parts of the lamp, it is then terminated to that connection which needs an earth connection from fuse board. Since you do not have an earth wire in your installation you need to introduce one or get a double insulated fitting.

cheif kaiser

WikiHow wrote: »

The loop that you are describing is the earth wire that is earthing other parts of the lamp, it is then terminated to that connection which needs an earth connection from fuse board. Since you do not have an earth wire in your installation you need to introduce one or get a double insulated fitting.

Even if there was an earth wire coming from the fuse box it would be attached to nothing, t would simply sit in the ceiling cavity as I have no other earth wire coming from the fitting to connect to it.

SpaceTime

cheif kaiser wrote: »

Even if there was an earth wire coming from the fuse box it would be attached to nothing, t would simply sit in the ceiling cavity as I have no other earth wire coming from the fitting to connect to it.

If it's not very new wiring, the is possibly no earth at the fitting as it was assumed you were using plastic double insulated simple lights..

You may need to get an earth run to the light fitting.

In older wiring they only earthed lights if a metal chandelier was planned or metal side lights.

You shouldn't fit a metal fitting that requires an earth.

Sir Arthur Daley

cheif kaiser wrote: »

Even if there was an earth wire coming from the fuse box it would be attached to nothing, t would simply sit in the ceiling cavity as I have no other earth wire coming from the fitting to connect to it.

You would connect the earth wire to the light fitting along with the wire of the light that is the loop that you call it to the connection at the middle of the fitting.

SpaceTime

Remember : just because it works doesn't mean it's safe.
Earthing won't make any difference to the operation of the light. It's just that there's a risk that one day you or someone else cleans it or changes a bulb and gets thrown across the room or even killed.

Comer1

Same problem for me here in Ireland. Can I earth the ceiling fan by running a cable from the earth in the pull cord for a shower to the fan.

Sorry for hijacking, didn't see the need to start a new thread.

Thanks

tomdempsey200

Comer1 wrote: »

Same problem for me here in Ireland. Can I earth the ceiling fan by running a cable from the earth in the pull cord for a shower to the fan.

Sorry for hijacking, didn't see the need to start a new thread.

Thanks

No
You cant borrow an earth off another circuit

Comer1

tomdempsey200 wrote: »

No
You cant borrow an earth off another circuit

Thanks, I was very wary of touching the shower anyway. Could I break into an earth cable going down to a socket?

tomdempsey200

Comer1 wrote: »

Thanks, I was very wary of touching the shower anyway. Could I break into an earth cable going down to a socket?

No
you have to to back to the board or else take an earth off the same circuit as the fan

Keep away from the pull cord anyhow
You might have problems if you go disturbing it

Comer1

tomdempsey200 wrote: »

No
you have to to back to the board or else take an earth off the same circuit as the fan

Keep away from the pull cord anyhow
You might have problems if you go disturbing it

This is sounding like more trouble that the few very hot days we get in the year are worth. The fan might be going back.

Zen65

cheif kaiser wrote: »

I understand why a light fitting needs to be earthed, I just can't understand why some light fittings are earthed to themselves by the manufacturer yet you say this is wrong?

The light fitting is not 'earthed to itself' - indeed doing so would serve no purpose. It is wired that way so there cannot be a voltage difference between the metal part of the bulb connector and the body of the lamp, such as may occur if some part of the lamp was either an insulator or if the bulb connection was detachable.

The earth connection (from house wiring) should be connected to the same screw as the one in the photo.