help please

[ed75]

we are in a housing association house and have noticed that the metal mounting boxes for the sockets in the kitchen and utility room have not been earthed.

we dont know when the work was done as the kitchen is not original but i expect it was it was within the last 20 years

does anyone know if the work would of had to have been checked or passed to have any certificate,i think the kitchen was fitted prior to the association buying the house

can anyone confirm if this is safe or whether we should get in touch with the housing regarding the matter?

 

[ColJack]

metal back boxes don't have to be earthed to comply with the regulations.. the screws take care of that when the front is screwed on.. and you shouldn't be taking the fronts off with the power still on..

it is however seen as good practice by most electricians to do so..

it harks back to the days when wiring was done in metal conduit, and the conduit itself was used as the means of earthing.. under those circumstances you still need an earth to the backbox..

 

[JohnD]

you do need to make sure that every socket has the earth wire of the cable connected to the earth terminal of the socket.

A lot of people like to put a 6" length of G&Y to the backbox from the socket terminal, this is a belt and braces.

However, if the earth wire from the cable is connected to the backbox (this is another way of doing it) then it is important to have this wire link between box and socket. Sometimes the lugs go rusty or screws are removed.

 

[Spark123]

Providing there is one fixed lug on the flush metal back box, the link between a socket and a metal backbox may be ommitted.
If it is a conduit install where the conduit was being used as the earth then this link must be installed.

 

[Chri5]

under those circumstances you still need an earth to the backbox..

Or from the back box to the socket earth position.

When CJ mentions the earth coming via the screw, to expand a bit.......

The socket faceplate will have a copper band from the earth terminal of the socket to the holes that the faceplate screws go through. So when metal screws are used to fix the faceplate to the back box, the earth on the socket is extended via the copper band and the screw to the metal of the back box.

Although in maybe of little interest this is the reason why a metal back box only ever has one floating screw lug. Once has to be hard fixed to 'firm' up the connection of the earth from screw to back box.

Generally it is accepted as very normal practice to have an earth strap wire between the socket earth terminal and the earth lug at the back of the back box.

As mentioned this is not a regulation, just 'good' practice.

 

[JohnD]

btw I sell these 6" G&Y links at 50p each plus P&P