Should my lights be earthed?

[amfisted]

Following on from a previous post about extra low voltage lights in a bathroom, I ended up replacing the old 240v downlights with IP44 lights of the same voltage. The original lights had supply wires which were two core only, meaning that they were connected to the lighting circuit via live and neutral, earth being blanked off. The installation diagram with my new lights--which are metal-- shows twin and earth connected, so I connected earth and it tripped the RCD; I disconnected earth so that I only had live and neutral connected and the RCD no longer tripped. The lights work perfectly and I can touch the metal body without being fried or tripping the RCD.
My consumer unit was fitted and certified just eighteen months ago by a qualified spark, so I know that side of things is working properly.

Are there any potential problems with this lighting setup?

 

[abrocky]

Did the rcd only trip when you put up this new light?

Sounds like it may be faulty, with the light disconnected, you can then test the fitting, neutral to earth.... If there is leakage it wud cause it to trip.... Doing its job!!

 

[PrenticeBoyofDerry]

So you have fitted extra low voltage lights (12V) with transformers?
But the MI states you connect to the earth terminal and then the RCD trips?
Are you sure you are connecting to earth?
As the previous lights were 240V, did this also require an earth to the fitting or was it double insulated or plastic?
If they did require an earth, strange that the earth was not connected, anything on the certificate issued 18 months ago about this?

 

[JohnW2]

So you have fitted extra low voltage lights (12V) with transformers?

I don't think so ...

Following on from a previous post about extra low voltage lights in a bathroom, I ended up replacing the old 240v downlights with IP44 lights of the same voltage.

Kind Regards, John

 

[PrenticeBoyofDerry]

So you have fitted extra low voltage lights (12V) with transformers?

I don't think so ...

Following on from a previous post about extra low voltage lights in a bathroom, I ended up replacing the old 240v downlights with IP44 lights of the same voltage.

Depends how you read it?
Could be same voltage as the previous post, that is why I asked for confirmation.

 

[JohnW2]

So you have fitted extra low voltage lights (12V) with transformers?

I don't think so ...

Following on from a previous post about extra low voltage lights in a bathroom, I ended up replacing the old 240v downlights with IP44 lights of the same voltage.

Depends how you read it? Could be same voltage as the previous post, that is why I asked for confirmation.

I don't think many people would read it that way! In any event, what the OP wrote in that previous thread, after the discussion about ELV lights, was:

.... I've now decided not to bother with the low--err, extra low--voltage lighting because I've measured my ceiling and it's almost as high as the ceiling of the Sistine Chapel. Will my 240 volt lighting still be required to conform to IP44, despite being above 2.25m?

QED!

Kind Regards, John

 

[RMS]

As you have stated, the lights require an earth. Your RCD will operate due to earth leakage and under certain conditions will limit the duration of electric shock. Potentially saving your life.

To remove the earth to eliminate unwanted tripping is not wise.

 

[Scoby_Beasley]

Some folks, where an earth is not required at the light point / switch, cut them off. Whereas what should be done is sleeve the earth and choc block/wago it for future use. An earth wire, even if not currently required, should never be trimmed back to negate its future use.

 

[JohnW2]

Some folks, where an earth is not required at the light point / switch, cut them off. Whereas what should be done is sleeve the earth and choc block/wago it for future use. An earth wire, even if not currently required, should never be trimmed back to negate its future use.

That's all very true, but (as I understand it) the OP has a metal light fitting which does have need/provision for an earth connection, but when he connects it, the RCD trips. That clearly indicates that soemthing is very, perhaps dangerously, wrong.

Kind Regards, John

 

[amfisted]

Thanks all for your replies. To confirm, the new lights I've fitted are 240 volt.

The following could be confusing, so apologies in advance. Confusion and electricity are obviously dangerous bedfellows, so I hope someone can make sense of this.

I know from working on other bits of the lighting circuit that all the other lights upstairs are earthed. The old downlights in the bathroom that I've just removed appear to have been put in when a false ceiling was installed, and pondering upon this further I think what may have happened is that someone has run an extension to that lighting which doesn't include a proper earth--or at least, not a wire which is functioning as earth. There's an extractor fan on a timer overrun in the bathroom, and there are two cables running from the ceiling rose within the false ceiling: one to the fan and the other to the lights. The "earth" wire on the cable running to the fan is connected to what according to the fan installation diagram should be "switched live", and on the cable running from the rose to the light fittings the "earth" was blanked off. I'm not sure of my ground here, but I'm assuming that the two cables from the ceiling rose share common terminals, and therefore the earth on the cable running to the lights is functioning as switched live rather than earth, and this is why it's blowing when I try to connect it to the lights. I think what I need to do is to trace this bodged cable back to where it joins the rest of the upstairs lighting circuit and replace the supply to the bathroom with a cable including an earth.

 

[securespark]

Not trying to be awkward, but how do you know the other lights on the circuit are earthed?

 

[amfisted]

No, it's fine, you've asked a reasonable question.
I've changed a couple of light fittings over the years and from doing that I know there's an earth in the supply cable.

I'm going to go back to the nearest junction box and start the supply to the bathroom again. Thanks all for your replies.

 

[amfisted]

Had a quick peek in the loft at all the cables, and there's definitely an earth. Can't get a proper look at the connections in the rose because it's obviously been installed before the false ceiling was put in just inches below it, so it's very difficult to see what's what without using a head torch and a mirror.

Mainly because of difficulty of access and the creeping realisation that I'm dealing with the Mother of all Bodges, I've decided to call a spark and get it checked out properly.

 

[calorific]

and therefore the earth on the cable running to the lights is functioning as switched live rather than earth.

That was a little charmer for someone to have left for the next someone to discover

 

[JohnW2]

and therefore the earth on the cable running to the lights is functioning as switched live rather than earth.

That was a little charmer for someone to have left for the next someone to discover

Indeed - and it's not the first time that has happened. Using the (insulated) G/Y of 3-core flex (sleeved red/brown at the ends) for the S/L to a Class II appliance is bad enough, but using the bare CPC of T&E for such a purpose is clearly way OTT, even if one does sleeve the ends appropriately!

Kind Regards, John