Metal light fixture

[DrGonzo]

Hi
I recently replaced a kitchen light with a metal light fixture.
Basically, I removed the old ceiling rose and rewired everything and attached the metal fixture instead.

All is working okay. However, it was slight struggle to get all 3 earth wires into their connection sockets, so I'm a little worried that one of the earthing wires may have come loose, or might in future. It mentioned in the instructions that the light had to be earthed, presumably because it's metal.
Is this in case the metal casing becomes live? If so, is there a way to test whether the light fixture is safe or would it just short out completely if something was wrong?

Thanks.

Oh...and why 3 earthing wires? If one has come loose, then will it be another part of the lighting system that is not earthed?

 

[breezer]

if one earth came loose it depends on what it was connected to as to what happens next

the reason you earth metal lights (and other things) is so that if a live wire touches it, the current is taken to earth ( this will blow the fuse / trip mcb) it is so that any one at a later date (say you) from being electrocuted when doing something as simple as changing a lamp

why not buy some large choc bloc and put all 3 earth wires in that and from the other side take a separate same sized sleeeved earth wire to the light, no worries then

 

[Spark123]

Yup, take a look at the wiring diagrams in the for reference section. If one of the wires is out then it could cause this fitting, its switch and any other lights/switches etc downstream or combination of said to be unearthed. If it is a bit tight to get the earth in the block you can buy additional block and terminate all the earths into it. With a short piece of earth wire (same size as lighting circuit) connect between the new piece of block and the lighting earth terminal.

 

[breezer]

Yup, take a look at the wiring diagrams in the for reference section. If one of the wires is out then it could cause this fitting, its switch and any other lights/switches etc downstream or combination of said to be unearthed. If it is a bit tight to get the earth in the block you can buy additional block and terminate all the earths into it. With a short piece of earth wire (same size as lighting circuit) connect between the new piece of block and the lighting earth terminal.

beat yah

 

[Spark123]

bah
Just goes to show great minds think alike

 

[DrGonzo]

Okay, I'll try that and reconnect it.
Is there anything you have to do after to test it, like do an insulation test or something similar ?

 

[breezer]

what do you propose to do an insualtion test with?

 

[DrGonzo]

To be honest, I have no idea!
Just wondering if there was something that is normally done after a light is fitted to see whether the metal is non-live.

?

 

[breezer]

so long as it is wired right and connections are fine and there is a known earth the light can not be live, since if it was there would be a bang

 

[DrGonzo]

Thanks for the pointers so far.

That's the bit I wasn't sure about.
I understand why you earth things, but if they're gonna blow anyway if a live wire touched the metal, then surely you could never be electrocuted anyway as you'd know that something was wrong?

So, there's no chance a metal cover can ever be live and the light still working at the same time?

 

[breezer]

not true

if the earth becomes dissconected then the light can become live.

like wise if the eart at the other end of said light became dissconnected and touched the live nothing would happen (by way of a bang) but the light would indeed be live.

it sometimes happens with street lights, dogs usualy find out first the hard way

 

[DrGonzo]

Surely this could happen just by accident sometimes? Wouldn't it be safer for people to change all lights in metal fittings by first turning off the electricty at the box?
I know no-one ever does but...?

 

[DrGonzo]

Is it worth getting some sort of voltage tester for this to check whether a metal fixture was live?
I know this is being over paranoid but where electricity's concerned...

?

 

[breezer]

so long as the earths are connected then all should be well.

how ever would you put nails in with out a hammer?

you should havea multimeter to check anything electrical (digital ones are cheap)

 

[DrGonzo]

Jesus, I haven't used one of those since school physics!

What do you recommend? Just switch it to voltmeter and touch the metal fixture with the probes?