High integrity earthing

[ban-all-sheds]

Only if you think that what started out as one piece of twin and earth contains "two individual protective conductors"...

 

[daytona]

i see the point BAS is trying to make ,its not difficult.

we take 2 2.5 t and e cables from mcb and wire in and out to make a loop through the accesories,so if we take a core out of the breaker and measure voltage on that cable then you have voltage.common sense says you have one cable.if not where would you define the start and finish of each cable?

it all changes when you get to the high integrity earth though.these are all separated just using the earth bar in the accessory for continuity.so for me in each outlet you have two earths

 

[Spark123]

But if one piece of twin and earth connects to one terminal in the earthing bar and the other piece of twin and earth connects to a different terminal in the earthing bar....
I mean like this:

 

[daytona]

you still only have one earth though,you just broke it everywhere you have an outlet

 

[Spark123]

Theres two individual paths connecting each point to the MET in the picture?

 

[tim west]

Bas its two cables in each socket bar the end one, that makes it a radial

Ban perhaps you are thinking of what is termed a radial circuit which has one wire of each L(Live) N(Neutral) E(Earth) whereas a RFC has two of each at each socket.

I'm not sure I should listen to you - I'm not sure you know what you're talking about.

Yes apologies Bas I called you Ban in the previous post so sorry.

Its quite simple really Bas you have two lives two neutrals and two earths at every socket in a RFC

 

[daytona]

SPARK 123 yes there is mate , i think in the circuit you have drawn out,there are clearly two terminations(in the CU),these are the ends of one piece of cable.

disconnect one earth from any socket and then you have two earths.is this what they were trying to say when they wrote the reg?
my books in the van and i cant be bothered to check the wording

im not sure i expalined that to well,i know what i meant though

 

[daytona]

[/quote]

Its quite simple really Bas you have two lives two neutrals and two earths at every socket in a RFC[/quote]




you do until you connect it up

 

[ColJack]

[code:1]607-03-01
blah, blah, blah.... The following arangements of the final circuit are acceptable:

i) blah.. blah.. blah..

ii) A radial final circuit with a single protective conductor:
a) the conductor being connected as a ring; or
b) a seperate protective conductor being provided at the FINAL socket outlet by connection to the metal conduit or ducting; or
c) ( paraphrasing ) cross connecting the earth at the end of 2 radials...[/code:1]

so if it's acceptable to use one earth along the length of a radial circuit and only take a single earth back from the last socket on it to the board , then why do you say it's not acceptable for a ring to be considered the same?



basically the reg requires that there is either 2 paths back to the earth in case one fails, or that the earth is of such a size or mechanically protected to prevent it's failure due to damage..

 

[tim west]

You have two physical cables at each socket they are not the same cable otherwise matter would be existing in two places at once.

 

[Spark123]

SPARK 123 yes there is mate , i think in the circuit you have drawn out,there are clearly two terminations(in the CU),these are the ends of one piece of cable.

disconnect one earth from any socket and then you have two earths.is this what they were trying to say when they wrote the reg?
my books in the van and i cant be bothered to check the wording

im not sure i expalined that to well,i know what i meant though

The reg we are talking about for high integrity earthing 607-02-04,
The wiring of every final circuit and distribution circuit intended to supply one or more items of equipment, such that the total protective conductor current is likely to exceed 10mA, shall have high a integrity potective connection complying with one or more of the following:
(i)
(ii)
(iii) two individual protective conductors, each complying with the requirements of section 543. The two protective conductors may be of different types e.g. a metallic conduit togtether with an additional conductor of a cable enclosed in the same conduit.

 

[daytona]

You have two physical cables at each socket they are not the same cable otherwise matter would be existing in two places at once.

yes you do.until you connect them up.would you expect an open circuit on your rings on a continuity check?

 

[tim west]

No id expect continuity but that still doesnt mean only one cable at each socket there are two physical cables at each socket in a RFC, count them if you dont believe me.

 

[daytona]

SPARK 123 yes there is mate , i think in the circuit you have drawn out,there are clearly two terminations(in the CU),these are the ends of one piece of cable.

disconnect one earth from any socket and then you have two earths.is this what they were trying to say when they wrote the reg?
my books in the van and i cant be bothered to check the wording

im not sure i expalined that to well,i know what i meant though

The reg we are talking about for high integrity earthing 607-02-04,
The wiring of every final circuit and distribution circuit intended to supply one or more items of equipment, such that the total protective conductor current is likely to exceed 10mA, shall have high a integrity potective connection complying with one or more of the following:
(i)
(ii)
(iii) two individual protective conductors, each complying with the requirements of section 543. The two protective conductors may be of different types e.g. a metallic conduit togtether with an additional conductor of a cable enclosed in the same conduit.

im well aware of the reg mate,just wasnt sure how it was worded.
if its worded as you say then i dont know why you can use purely the cpc in the twin and earth.the reg implies this is not enough surely.
i know we all do it but is that reg is wrong,or we are installing it wrong.

PS why has everyone started writing really wide posts,they dont fit on my screen

 

[daytona]

No id expect continuity but that still doesnt mean only one cable at each socket there are two physical cables at each socket in a RFC, count them if you dont believe me.

obviously if you look at the socket there are two cables.the point that some are trying to make is this.
although you have two physical cables at the socket,the effects when connected and energised,are as one.

if you take a brown out of a breaker and re-energise the circuit and grab that cable,you will get a belt.check if you dont believe me,if your not shaking to much afterwards,then you could reply with something less patronising.