Lighting circuit with no earth but RCD fitted - safe or not?

[m666bel]

Hi,

Recently purchased an older property, have found that the lighting circuit is wired in twin core only - no earth. Wires look OK, grey PVC sheathed and don't look like they need replacing in themselves. Someone has installed a 30mA RCD between meter and consumer unit at some point as well (I think a 100mA RCD is more usually used in this position?) .

My question is this. If I want to install a metal light fitting (not double insulated), does the RCD give sufficient protection or do I have to earth the whole lighting circuit? Fitting an earth wouldn't be that easy so I'd like to avoid this if possible.

Thanks
Michael

 

[electronicsuk]

My question is this. If I want to install a metal light fitting (not double insulated), does the RCD give sufficient protection or do I have to earth the whole lighting circuit? Fitting an earth wouldn't be that easy so I'd like to avoid this if possible.

Sorry, but if you want to avoid earthing the circuit then you'll have to fit a class II double insulated light fitting, nor should you fit any metal switch plates if there is no earth anywhere on the circuit. There's a wide choice available.

 

[comms]

http://www.double-insulated-lighting.co.uk/?gclid=CJ6kroGwz58CFV1d4wod2VuThg

 

[Steve]

Recently purchased an older property

Then you wont have decorated the place yet, and knocking the place about to rewire the lights will be ok . . . .

 

[dingbat]

Hi,

Recently purchased an older property, have found that the lighting circuit is wired in twin core only - no earth...

...if I want to install a metal light fitting ...

...Fitting an earth wouldn't be that easy so I'd like to avoid this if possible.

The lack of a circuit protective conductor in the lighting circuit was a common practice prior to 1966.

This suggests that your wiring is at least 44 years old.

Therefore, you either have nowhere near enough socket outlets for a modern house, or else somebody (possibly several somebodies) has modified the socket circuit/s, probably without any form of testing and possibly introducing potential hazards.

Did you get the electrics inspected/tested before you moved in?

Thought not.

Forget the shiny metal light fitting and get the place rewired; it's a false economy to tart up a place before sorting out the basics.

 

[NotHimAgain]

Using an RCD as a means of fault current protection on a circuit with no circuit protective conductor (earth wire) - is specifically prohibited by BS 7671 [531.2.5] - if that circuit would normally be expected to have a circuit protective conductor.

So you should take the advice given by others and rewire.

 

[PrenticeBoyofDerry]

The expected live of domestic cables is approx 40-50 years.
This will depend on other factors ie usage and load of these circuits.
So as others have said, over this period wear/tear could well have effected the installation. Plus the fact that any addition to or of circuits installed over that period, may not be as they should be.
You have just bought it, ideally it should have come with an periodic inspection report, but this seldom seems to happen.
I also expect some of the installation wont be suitable to your requirements and some updating/modernizing will be required.
So I'd say it's time to think about an upgrade and rewire the property.