High integrity earthing

[ban-all-sheds]

Any reason why the earths are terminated like that.
The socket earth bar is now acting as part of the earth continuity conducter.

High integrity earthing

Not wired like that with a single cpc....

 

[RF Lighting]

I dont follow?

There is a CPC from each of the t&e cables

 

[ban-all-sheds]

The circuit has one cpc - it comes in at that socket and goes out from it.

High integrity earthing requires two completely separate cpcs, i.e. you'd expect to see 4 g/y conductors, 2 coming in, 2 going out. They must be terminated independently of each other at all points, so if an additional single is added to supplement the T/E core, both T/E cpcs must go to one terminal and both supplementary ones to the other terminal.

 

[RF Lighting]

But providing the circuit is a ring, and providing both conductors are terminated independantly of each other at all connection points throughout the entire circuit, then no additional seperate protective conductor is required.

 

[ban-all-sheds]

It probably isn't. UNLESS there's an expectation of high cpc currents and THEREFORE a high integrity circuit protective connection is required as per 607-03-01/543.7.1.3 IN WHICH CASE if the main cable is 2.5mm² T/E a 2nd cpc is required.

And in that case they'd be connected to different terminals in the socket.

Basically the suggestion that the regular ring final cpc has been connected to the terminals separately because high integrity earthing is required doesn't wash. High integrity earthing is almost certainly not required, but if it is then a single 1.5mm² cpc won't do it, whether connected as per usual, or to both terminals as in this case.

 

[NotHimAgain]

BAS Wrote

Basically the suggestion that the regular ring final cpc has been connected to the terminals separately because high integrity earthing is required doesn't wash. High integrity earthing is almost certainly not required, but if it is then a single 1.5mm² cpc won't do it, whether connected as per usual, or to both terminals as in this case.

There maybe some confusion here - a ring final circuit wired using 2.5mm²/1.5mm² PVCTWE cable can be used to form a circuit with 'high integrity' earth provided that each connection is separated - i.e. terminated under different screws.

The group of regulations that form section 607 (now 543) have been altered many times and some clarity may have been lost - refer to GN 7 for confirmation of the intention.

Now is such a circuit required - probably unlikely. Equipment containing low pass supply filters is usually (but not exclusively) to blame for high protective currents. This includes IT equipment but anything with electronics 'on board' may contain a filter. Equipment can pass 3.5mA to earth in the form of deliberate protective conductor current - but most is a factor of 10 lower than this.

However, the good old cooker element is allowed to leak 10 mA to earth .

 

[ban-all-sheds]

There maybe some confusion here

Not in my mind.

a ring final circuit wired using 2.5mm²/1.5mm² PVCTWE cable can be used to form a circuit with 'high integrity' earth provided that each connection is separated - i.e. terminated under different screws.

Not according to my copy of the 16th..

The group of regulations that form section 607 (now 543) have been altered many times and some clarity may have been lost - refer to GN 7 for confirmation of the intention.

Well I would if I had a copy of GN7, but the intention of 607 is surely what 607 actually says? And it doesn't say that IF a socket outlet final circuit needs high integrity earthing that a single 1.5mm² cpc is OK.

 

[NotHimAgain]

Extract: 607-02-06 16ŧħ Edition Red Copy
Last two sentences
There shall be no spur from the ring and the supply ends of the protective conductor ring shall be separately connected at the distribution board. The minimum size of the protective earth conductor shall be 1.5 mm².

Extract: Current Text 16th Edition Brown Copy
607-03 Socket-outlet final circuits

607-03-01 For a final circuit with a number of socket-outlets or connection units intended to supply several items of equipment, where it is known or reasonably to be expected that the total protective conductor current in normal service will exceed 10 mA, the circuit shall be provided with a high integrity protective conductor connection complying with the requirements of Regulations 607-02 and 607-04. The following arrangements of the final circuit are acceptable:

(i) a ring final circuit with a ring protective conductor. Spurs, if provided, require high integrity protective conductor connection complying with the requirements of Regulation 607-02

------------------
Spurs are now permitted but if used THEY must high integrity protective conductor.

GN 7 includes diagrams showing exactly what I am saying.

 

[ban-all-sheds]

Extract: 607-02-06 16ŧħ Edition Red Copy

Superseded.

Extract: Current Text 16th Edition Brown Copy
607-03 Socket-outlet final circuits

607-03-01 For a final circuit with a number of socket-outlets or connection units intended to supply several items of equipment, where it is known or reasonably to be expected that the total protective conductor current in normal service will exceed 10 mA, the circuit shall be provided with a high integrity protective conductor connection complying with the requirements of Regulations 607-02 and 607-04.

And those requirements are?

 

[NotHimAgain]

Well we could go on all day couldn't we.
Why do you think they decided to emphasis the requirement for spurs over sockets on the ring.

This text was written by engineers and that probably says it all - the text from the red book was, IMO, much better - but then I would say that wouldn't I because I had a hand in writing it .

 

[ban-all-sheds]

Well we could go on all day couldn't we.

Or we could look at what the requirements of Regulations 607-02 and 607-04 are.

Why do you think they decided to emphasis the requirement for spurs over sockets on the ring.

I don't know. Does the emphasis change what the requirements of Regulations 607-02 and 607-04 are?

This text was written by engineers and that probably says it all

What did the engineers write for the requirements of Regulations 607-02 and 607-04?

the text from the red book was, IMO, much better - but then I would say that wouldn't I because I had a hand in writing it .

But what the red book said is irrelevant.

 

[NotHimAgain]

[q]Or we could look at what the requirements of Regulations 607-02 and 607-04 are.[/q]

If we must - 604 first because that is easy - all we have to do is comply with 543-1 no problem we will just use the adiabatic equation.

Now 602 - take a close look at 607-02-04 (iii) paragraph 2 - ring circuit (4 * 2.5) + (2 * 1.5) = ?

 

[Spark123]

^^Did anyone notice the smilie after what I wrote? If a socket is OK wired like this for high integrity earthing then why is it not OK for a normal RFC?

 

[securespark]

To me, 607-02-04 (iii) implies it is OK to use a RFC, which is listed as "acceptable" in 607-03-01.

I interpret 607-03-01 (i) to mean that it is listed as "acceptable" because it already complies with 607-02 and 607-04.

 

[Spark123]

GN7 and GN8 both say it is OK basically providing those points rob made before are met.