Cable for burying in plaster

Pandybelly

Hi,

I have just had a wall built around my garden and intend to light a high section of it with wall lights. I also intend to fit two outdoor sockets for power washer etc.

I want to run 1.5mm for the lights and 2.5mm for the socket boxes. I am familiar with NYMJ cable but am getting mixed advice on whether it can be:
1. Buried unprotected in soil.
2. Plastered into a wall without conduit.

I want to use a cable that reduces the need for conduit and underground protection. The cable will be run along the base of the wall and will not be crossing any pathways, lawn areas etc so the risk of it being disturbed are minimal. I intend covering it with marker tape to alert anyone in the future to its presence. My overall run is about 20m underground.

I have come across a cable via Google called NYYJ that appears to be suitable for burying.

All advice appreciated.

Risteard81

Pandybelly wrote: »

I have come across a cable via Google called NYYJ that appears to be suitable for burying.

Commonly known as Hi-Tuff. It's used quite a bit in the north. Whilst suitable for outside use it is every bit as unsuitable as NYM-J for burial. I would expect to see an SWA type cable. Needless to say the armour MUST be earthed.

2011

+1 to the above.

It is important to note that NYMJ is not UV resistant.
This means that if used outdoors it must be shielded from sunlight either by use of a suitable conduit or otherwise.

2011

Just to add I misread the OP, I thought the suggestion was to use NYMJ.

Pandybelly

Risteard81 wrote: »

Commonly known as Hi-Tuff. It's used quite a bit in the north. Whilst suitable for outside use it is every bit as unsuitable as NYM-J for burial. I would expect to see an SWA type cable. Needless to say the armour MUST be earthed.

Hi Risteard,

When you say the armour must be earthed, do you mean in the consumer unit earth bus bar, in the sockets earth pin or both?
Thanks.

aido79

Pandybelly wrote: »

Hi Risteard,

When you say the armour must be earthed, do you mean in the consumer unit earth bus bar, in the sockets earth pin or both?
Thanks.

If you have to ask this then you probably shouldn't be doing the job.
Without connecting an earth at the consumer unit the earth pin in a socket is just a piece of metal. It's not until it is connected via the earth wire to the earth bar of the consumer unit that it becomes an earth.
There are specific glands that should be used for armoured cable which connect to the armour that an earth can be connected to. The glands would generally be fitted off into metal back boxes to make this easier.
Hope this helps.

confusedeire

aido79 wrote: »

If you have to ask this then you probably shouldn't be doing the job.
Without connecting an earth at the consumer unit the earth pin in a socket is just a piece of metal. It's not until it is connected via the earth wire to the earth bar of the consumer unit that it becomes an earth.

Wouldn't the socket be earthed through the earth wire? This would be connected to the earth pin in the socket and the earth bar connectors.

aido79

confusedeire wrote: »

Wouldn't the socket be earthed through the earth wire? This would be connected to the earth pin in the socket and the earth bar connectors.

Yes it would but that doesn't earth the armour.

Risteard81

Pandybelly wrote: »

Risteard81 wrote: »

Commonly known as Hi-Tuff. It's used quite a bit in the north. Whilst suitable for outside use it is every bit as unsuitable as NYM-J for burial. I would expect to see an SWA type cable. Needless to say the armour MUST be earthed.

Hi Risteard,

When you say the armour must be earthed, do you mean in the consumer unit earth bus bar, in the sockets earth pin or both?
Thanks.

Sorry I've only seen your question now. I trust the existing answers have answered your question?

Basically you need to remember that, regardless of whether a separate core is being used for the protective conductor or whether the armour itself is being used as the protective conductor, that the armour is an exposed conductive part and therefore must be earthed.

Furthermore, as with steel conduit, the armour is not sufficient to prevent penetration. The mechanical protection operates on the basis that it is earthed and therefore will operate the protective device should it be penetrated and then a live part be penetrated.

Pandybelly

Risteard81 wrote: »

Sorry I've only seen your question now. I trust the existing answers have answered your question?

Basically you need to remember that, regardless of whether a separate core is being used for the protective conductor or whether the armour itself is being used as the protective conductor, that the armour is an exposed conductive part and therefore must be earthed.

Furthermore, as with steel conduit, the armour is not sufficient to prevent penetration. The mechanical protection operates on the basis that it is earthed and therefore will operate the protective device should it be penetrated and then a live part be penetrated.

Hi Risteard,

Thanks for confirming that.