Earth wire question.

[mart]

An outdoor lamp fitting is constructed of plastic non-conducting material. The manufacturer supplies this lamp fitting with a short length of 2 core (live & neutral) wire inside, connected to the bulb holder on one end, and the usual plastic block connector on the other end. All quite normal.

If for example a 3 core cable is run to this lamp, (whether it is armour, TW&E or the IP rated rubber sheath type), what would you do with the earth at the lamp end?

I heard that an earth that is not connected to anything over time will build up and retain a certain amount of current that one can get a "belt off". Is it officially considered bad practice to use 3 core on something like this? What if the end of the earth was connected to one of the securing screws holding the lamp to the wall for example, instead of leaving it unconnected? Or, is it just better to simply use 2 core cable?

 

[brightspark]

An outdoor lamp fitting is constructed of plastic non-conducting material. The manufacturer supplies this lamp fitting with a short length of 2 core (live & neutral) wire inside, connected to the bulb holder on one end, and the usual plastic block connector on the other end. All quite normal.

If for example a 3 core cable is run to this lamp, (whether it is armour, TW&E or the IP rated rubber sheath type), what would you do with the earth at the lamp end?

I heard that an earth that is not connected to anything over time will build up and retain a certain amount of current that one can get a "belt off". Is it officially considered bad practice to use 3 core on something like this? What if the end of the earth was connected to one of the securing screws holding the lamp to the wall for example, instead of leaving it unconnected? Or, is it just better to simply use 2 core cable?

every point must be earthed no matter weather it is used or not. if the fitting and lampholder are both plastic just termiate the earth wire off with a conector. its also benificial if u ever change it to a fitting with a metal lampholder and fitting that requires an earth or u may want to loop another light of it at sometime

 

[sparkysy]

Hi mart the earth from the supply cable should be sheathed in green and yellow sleeving and put in a connector of some sort just in case someone at a later date chooses a class 1 light fitting (metal) where you would need it yours is class2 so double insulated no exposed parts! The earth at the other end of the circuit would be connected in the consumer unit to the earth bar and as such should a fault occur will protect the installation! Hope that helps. Sy

 

[mart]

OK, so put some earth sleeving on the earth wire , then put a plastic block connector on the end and a bit of green insulation tape around the block connector, and leave it tucked inside the lamp where the other wires are. (There is no need to fasten the end of the earth wire to one of the screws that are holding the lamp fitting to the wall, and no risk of a current build in the earth wire). Have I got all of that correct?

 

[Robotstar5]

OK, so put some earth sleeving on the earth wire , then put a plastic block connector on the end and a bit of green insulation tape around the block connector, and leave it tucked inside the lamp where the other wires are. (There is no need to fasten the end of the earth wire to one of the screws that are holding the lamp fitting to the wall, and no risk of a current build in the earth wire). Have I got all of that correct?

No, because the other end is earthed.

 

[brightspark]

the only time u get voltage on an earthwire is if its not been conected back at source and u can get residual current over the system which is roughly about 50 volts

 

[Robotstar5]

the only time u get voltage on an earthwire is if its not been conected back at source and u can get residual current over the system which is roughly about 50 volts

I'm sure I read somewhere you can get voltage on the big rolls of cable the supply companies bury, capacitor effect?.

 

[mart]

the only time u get voltage on an earthwire is if its not been conected back at source and u can get residual current over the system which is roughly about 50 volts

OK