Functional earth ( clean earth )

[hatha101086]

Ok, good afternoon all, this is my first post on here so please all be gentle,

My question is this, my boss at work has read the spec and confirmed the computer ring mains require a 'clean earth', we shall be wiring in 4.0mm single for all conductors and then 2.5mm single for the extra cpc.
They are then all connected individually into the DB into the SAME earth bar - surely a separate clean earth should go onto a seperate earth bar?!?
The circuits are all protected with RCBO' so when connecting the earth of the rcbo - do you connect with the 4.0mm or 2.5mm?!?
I know this belongs in another topic but i'm going to slide it in here - when testing, do you test using the 4.0mm cpc and then record the 'clean earth' as a single R2 result?

Many thanks once again, and please be gentle. cheers all

Mark

 

[High Tower]

That's not what's required, high integrity earthing should consist of a standard ring or radial and using standard sockets that incorporate dual earth terminals. Where By each leg is connected to a separate terminal. Further to that at the consumer unit the legs are also split up in the Earth bar where circuit one would occupy number one and number two positions in the Earth bar Circuit two would also occupy number one and number two positions in the bar. This insures that in the event of either Leg being disconnected that earthing integrity is not lost and when items of high leakage currents are connected such as IT equipment there is no further risk. Care should also be taken to apply the appropriate sticker to the consumer unit warnings of high CPC current

 

[hatha101086]

Thank you for your response,
All our specs state dual earth terminals as standard for sockets, this spec however states that we pull in an extra cpc for each ring main and radial circuit where a computer is in use.

 

[Guest123]

An informative PDF.......

 

[hatha101086]

Thanks, so at a quick glance i believe that you do not have to pull in an extra cpc for ring mains as there will always be a way back to earth as long as dual earth terminals are used on the sockets. so if you repeat this process with a radial cpc then you are covered...

 

[Des 56]

As I read it, if the leakage on the radial circuit exceeds 10 m/amp you may need a 10mm, or a 4mm with additional mechanical protection,worth checking the likely equipment being used

 

[High Tower]

The way it reads to me is if the current exceeds 10mA then a 10mm earthing conductor is required OR a 4mm with mech protection OR two cpc's

 

[Engineer54]

Ok, good afternoon all, this is my first post on here so please all be gentle,

My question is this, my boss at work has read the spec and confirmed the computer ring mains require a 'clean earth', we shall be wiring in 4.0mm single for all conductors and then 2.5mm single for the extra cpc.
They are then all connected individually into the DB into the SAME earth bar - surely a separate clean earth should go onto a seperate earth bar?!?
The circuits are all protected with RCBO' so when connecting the earth of the rcbo - do you connect with the 4.0mm or 2.5mm?!?
I know this belongs in another topic but i'm going to slide it in here - when testing, do you test using the 4.0mm cpc and then record the 'clean earth' as a single R2 result?

Many thanks once again, and please be gentle. cheers all

Mark

Your describing a high integrity earth here, Not a so-called ''Clean Earth'' so all would connect to the same CU earth bar!!

Now you have to ascertain if the installation your installing will exceed the 10mA leakage limit, ...if it does then you will also have to meet the earthing requirements as stipulated in the link above...