RCD question please

[Sav]

Hi people,

Does an rcd detect a neutral fault or is it just and earth / live fault ??
Also, would you run a separate earth with a 16mm or higher swa cable??

Thanks

Sav

 

[Guest123]

Hi.

An RCD will operate upon sensing of an earth fault i.e line to earth or neutral to earth as it monitors the current flow between line and neutral. There is no overload protection, fuses and MCB's provide that.

As for seperate earths it depends on number of cores as the armour size varies with these too.

 

[ian.settle1]

Hi people,

Does an rcd detect a neutral fault or is it just and earth / live fault ??
Also, would you run a separate earth with a 16mm or higher swa cable??

Thanks

Sav

An RCD works on that it monitors what current goes down the live comes back down the neutral (single phase) if there is a difference between them of more than 30mA for a 30 mA RCD it will trip.

So if there is a fault between N & E it will trip.

 

[Sav]

Hi Lenny,
Thanks for the reply. So if say I was running a 16mm swa from a house to a storeroom supply, would you suggest running an extra, say 10mm earth for additional protection ??
An old boss of mine said there is no need to , but another guy said its best to as its over 10mm swa and to be within regs /readings. I cant find it in the BS7671 or OSG where it advises this.
Please help .
thanks again in advance
Sav

 

[Guest123]

Hi Sav.

If you look at the table in the link it gives the copper equivalent size of the steel armour.

Values that comply are in green, ones that dont are in red.


http://www.earthingnuts.co.uk/pdf/pvc_xlpe.pdf

 

[ian.settle1]

Hi Lenny,
Thanks for the reply. So if say I was running a 16mm swa from a house to a storeroom supply, would you suggest running an extra, say 10mm earth for additional protection ??
An old boss of mine said there is no need to , but another guy said its best to as its over 10mm swa and to be within regs /readings. I cant find it in the BS7671 or OSG where it advises this.
Please help .
thanks again in advance
Sav

Have worked on many sites where what ever it says in the regs a seperate CPC half the size of the main cable must be installed way it is going as sepecified by main site.

 

[Guest123]

Must admit I always do.