High integrity earthing

[Guest 004]

Can anybody here give some examples of this, and in what situations it would be used?

More importantly my understanding is that you would need an extra bar at the DB, which is then maybe insulated?

 

[Guest123]

Most commonly found in IT suites due to the high earth leakage current of the equipment associated with them.

543.7 refers.

Also see attached PDF.

 

[Deleted member 26818]

The extra bar at the DB is not really that necessary, I don't quite know what you mean by insulated.
Obviously it will be insulated from any live conductors or bars.
There are two methods for providing high integrity earthing.
one is to use a substantially larger CPC than is normally used, the other is to use a second CPC.
When using a second CPC, the conductors should be terminated in different terminals from those for the first CPC.
This is where a second earth bar would be used, if ther is only one earth bar, then the usual practice is to terminate the second CPC in the terminal next to the first CPC. This will often entail doubling up conductors with those of a different circuit.

 

[Guest 004]

The extra bar at the DB is not really that necessary, I don't quite know what you mean by insulated.
Obviously it will be insulated from any live conductors or bars.
There are two methods for providing high integrity earthing.
one is to use a substantially larger CPC than is normally used, the other is to use a second CPC.
When using a second CPC, the conductors should be terminated in different terminals from those for the first CPC.
This is where a second earth bar would be used, if ther is only one earth bar, then the usual practice is to terminate the second CPC in the terminal next to the first CPC. This will often entail doubling up conductors with those of a different circuit.

well that differs from the pdf doc

 

[Deleted member 26818]

Does it?
I'm not really suprised, as from glancing at the document I note that it is written by Mark Coles.
I'd suggest that rather than relying on Mark's opinions, you have a look at Section 543.7 in BS7671.

 

[telectrix]

the pic on page 10 is useful. also, you would use socket outlets with 2 earth terminals and connect 1 cpc leg to each, rather than the more usual way of puuting both in 1.

 

[Deleted member 26818]

the pic on page 10 is useful. also, you would use socket outlets with 2 earth terminals and connect 1 cpc leg to each, rather than the more usual way of puuting both in 1.

The two terminals are intended for two separate CPCs, one CPC in one terminal and the other CPC in the other terminal.
If only one CPC is being used, there is no need to use socket-outlets with two terminals.

 

[telectrix]

The two terminals are intended for two separate CPCs, one CPC in one terminal and the other CPC in the other terminal.
If only one CPC is being used, there is no need to use socket-outlets with two terminals.

hmm, i was taught , rightly or wrongly, that if, say, the circuit was a ring final, then you used both terminals in case of a break in 1 cpc, i'll have a read of 543.7, the guy that tol,d me the above, however, was adamant that fly leads must be fitted to back boxes. tbh, it's not something i come across , so have not bothered to research hi integrity earthing fully.

 

[Deleted member 26818]

"543.2.7 Where the protective conductor is formed by conduit, trunking, ducting or the metal sheath and/or armour of a cable, the earthing terminal of each accesory shall be connected by a separate protective conductor to an earthing terminal incorporated in the associated box or other enclosure."
"543.7.1.4 Where two protective conductors are used in accordance with Regulation 543.7.1.3 (iii), the ends of the protective conductors shall be terminated independantly of each other at all connection points throughout the circuit, e.g. the distribution board, junction boxes and socket-outlets. This requires an accessory to be provided with two separate earth terminals."

 

[Guest 004]

I fail to see where you would this type of circuit, other than in IT rooms, or MER's, and SER's