Do lights Need To Be Earthed

[DeludedAussie]

Firstly when installing downlights there is no wire for the earth cable. There is only live and neutral

So what are you meant to do in this case. What tends to happen is the earth cable is just not wired up but I am using a metal switch and there are children in the house

Also can anyone explain in one sentence why earthing needs to happen? Wont the RCD provide your break if anything wrong happens

 

[ban-all-sheds]

What tends to happen is the earth cable is just not wired up but I am using a metal switch

How does not having an earth at a light stop you from having one at a switch?

and there are children in the house

Then shame on you for putting their lives at risk by working on the electrical installation in that house when you are clearly desperately incompetent.

Also can anyone explain in one sentence why earthing needs to happen?

To stop any exposed conductive parts from becoming live for any length of time if there's a fault.

Wont the RCD provide your break if anything wrong happens

Not necessarily.

And why choose to get a shock, even a small one, over having the supply automatically disconnect if an exposed conductive part becomes live?

 

[OwainDIYer]

If there is no earth wire (tested for continuity back to the main earth terminal) you MUST NOT use metal switches or other accessories.

The RCD provides additional safety (compared to not having an RCD) if you touch something live. It is not guaranteed to protect against fatal electric shock, especially for children.

The metal switch etc must be earthed so that, if there is a fault and it becomes live, the current flows straight to earth and the MCB or RCD will operate quickly, and without you having to touch a live thing.

 

[ericmark]

There are instructions See this by the Electrical safety council but the rules were changed in the 1960's on earthing lights and electrical installations should be tested every 10 years or change of occupier which ever is shortest time so between the 1960's and now the problem should have been raised at least 4 times so the owner should be well aware of the problem and has had at least 40 years to correct it.

I think personally 40 years is enough and any new owner would be told about the problem when the electrical installation condition report to submitted to the solicitor so to my mind no real question you should know it needs a re-wire.

In the mean time you have to accept that all switches must be plastic and all light fittings must the double insulated you just can't use any fancy metal light fittings. There are 2D florescent fittings which are double insulated but they are more expensive.

There is a firm who specialise in double insulated so loads of temporary work around but you should really think of it as temporary and realise at some point in the near future you need a rewire.

 

[SaladFingers]

Then shame on you for putting their lives at risk by working on the electrical installation in that house when you are clearly desperately incompetent.

 

[bernardgreen]

Also can anyone explain in one sentence why earthing needs to happen? Wont the RCD provide your break if anything wrong happens

If there is no earth connection to the metal switch plate then there can be no path for current to earth other than through a body if there is a fault and if there is no earth current the RCD will not have an in-balance between Live and Neutral current ans therefor will be unable to trip.

Get an electrician in to make your electrics safe before you have to call an ambulance for a casualty, a victim of your incompetance

If there is 30 mA flowing through your child from the switch plate then the RCD is likely to trip but for a small child 20 mA can cause serious harm and could be fatal before the RCD trips if it does trip.

 

[SaladFingers]

The grammar is quite bad in OPs post, so can't work out if this is intended work or work which has been 'done now ask later'.

 

[DeludedAussie]

The grammar is quite bad in OPs post, so can't work out if this is intended work or work which has been 'done now ask later'.

Does every point in the house need to be earthed?

I am taking the power supply from a socket which is earthed but on the light switch cable I cut the earth cable too short and it is in the wall so cannot be replaced.

Would the earthing point in the socket (providing the power supply) be sufficent?

 

[Grizzly]

Great.
Yet another dimwit with (text-based forum equivalent of) selective deafness.

 

[Chri5]

Oh let's take a feed froma 30 amp odd socket circuit and run that to a light without worrying about earthing


Look you are being dangerous, please get a spark in or accept our advice.

A light feed from a socket should be fused down via a fused spur. So you take a LNE to the fused spur from the socket, you then fuse down at an appropriate level for the lighting cable and the light demand 3 amp is common and covers all but daft lighting loads.

From the fused spur on the load side you run 1mm or 1.5mm TE to the switch. If the switch is metal you will have a earth point which MUST be earthed.
If the switch is plastic there is no earth, so the earth the terminates on the back box earth stud. Your onward feed to the fitting or series of fittings will again be TE cable.
There is no such thing as can't be done, so dig out the wall and replace the cable with no usable earth.

Now the neutrals get joined in the box via wago or block terminal. The earths get joined by the metal switch earth point, or if a plastic switch, the back box stud.
The live feed goes to one side of the switch and the switched live to the fitting the other.

Knowingly doing a bodge is criminal, so please get away from the mind set of "will do".

You might want to read up on how RCDs work before you post up how they will prevent injury without an earth connected

 

[ban-all-sheds]

The grammar is quite bad in OPs post, so can't work out if this is intended work or work which has been 'done now ask later'.

Check his other posts.

 

[ban-all-sheds]

Does every point in the house need to be earthed?

It needs to have one running to it.

I am taking the power supply from a socket which is earthed but on the light switch cable I cut the earth cable too short and it is in the wall so cannot be replaced.

You can't use it then. Simples.

 

[ericmark]

In a house you are allowed 20 W without an earth connection if you use a approved isolation transformer, it is the only IT supply allowed in a house.

IT means the supply is isolated from terra firma (earth) hence the IT label. The only place these are used is in a bathroom. And most lamps need more than 20W so in most cases you could not use a shaver socket to run lighting.

All other outlets in a house need an earth.

 

[Spark123]

I think you mean protection by electrical separation?? An isolating shaver socket isn't an IT (insulated terra) device as the shavers case isn't connected to ground via an electrode (and they are usually double insulated.)

IT = the source is isolated from earth or earthed via a high impedance, T = the consumers installation is earthed via an electrode or similar. I have only ever seen one installation I'd class as IT in my almost 20 years of sparkying, that was in a test bay.