Advice on regulation 521.5.1

[andyb]

Yep my words, so go back, read and UNDERSTAND the regulation.

Paragraph 3

These requirements do not preclude the use of an additional protective conductor in parallel with the steel wire armouring of a cable where such is required to comply with the the requirements of the appropriate regulation in chapters 41 and 54.It is permited for such an additional protective conductor to enter the ferrous enclosure individually.

 

[davesparks]

Yes, as I said, read and UNDERSTAND the reg.
Where it is REQUIRED.
If it is not REQUIRED then it is NOT ALLOWED.
So, if you can generate a scenario where it is REQUIRED, then it is ALLOWED.
However, I doubt you can actually prove a reason to install a separate cpc.
Look it up do the calcs, and then come back and show where a seperate cpc is REQUIRED, considering that the SWA must act as an adequate CPC for the circuit anyway else it is not acceptable.

I have already mentioned the situation where a seperate protective conductor is required, that of needing a main bond. The regulation states protective conductor not circuit protective conductor. Bonds are protective conductors.

 

[netblindpaul]

Paragraph 3

These requirements do not preclude the use of an additional protective conductor in parallel with the steel wire armouring of a cable where such is required to comply with the the requirements of the appropriate regulation in chapters 41 and 54.It is permited for such an additional protective conductor to enter the ferrous enclosure individually.

Like I said, read and understand, REQUIRED is the relevant word.
If REQUIRED, it's OK, when is it REQUIRED?
If it's not REQUIRED, then it's NOT OK, just like I said.

 

[netblindpaul]

How does the conductor know that it is a bond and not a cpc? the armour as cpc and the seperate bond are effectively connected together at each end, so any flow of current is going to split between them proportionally.

In which case as the fault current WILL be split equally then it is a requirement that the armour WILL take the full fault current, thus the additional wire is not required.
The fault current will NOT split proportionally between the two conductors, at least not according to the research undertaken by the independent body that is the ERA.
Thus the SWA & the additional "cpc" must be capable of carrying the full fault current, thus, there is no need for the additional cpc.
QED.

 

[shanky887614]

states within the same enclosure not entry point so whats wrong.

L+N dont need to go through together if you slot it, or use paxolin/similar

 

[spadge47]

I presume main protective bonding conductors are also appropriate protective conductors and therefore they need to enter through the same hole as the main tails if they all had to enter the same.

 

[andyb]

They don't allow it to enter through a different point, never have.

Wrong, read 521.5.1

Not according to the copy I have here.

Send your copy back & get a genuine one.

Yes, as I said, read and UNDERSTAND the reg.
Where it is REQUIRED.
If it is not REQUIRED then it is NOT ALLOWED.
So, if you can generate a scenario where it is REQUIRED, then it is ALLOWED.
However, I doubt you can actually prove a reason to install a separate cpc.
Look it up do the calcs, and then come back and show where a seperate cpc is REQUIRED, considering that the SWA must act as an adequate CPC for the circuit anyway else it is not acceptable.

You're now saying it is allowed I think.

 

[davesparks]

In which case as the fault current WILL be split equally then it is a requirement that the armour WILL take the full fault current, thus the additional wire is not required.
The fault current will NOT split proportionally between the two conductors, at least not according to the research undertaken by the independent body that is the ERA.
Thus the SWA & the additional "cpc" must be capable of carrying the full fault current, thus, there is no need for the additional cpc.
QED.

It will split proportionally, it will not split equally. I've read differing information on exactly what those proportions will be, with a general consensus that the majority of the fault current will flow through the armour.
I am not talking about an additional cpc, I am talking about a bond run in parallel with the armour (as cpc), this is still a protective conductor

 

[davesparks]

states within the same enclosure not entry point so whats wrong.

L+N dont need to go through together if you slot it, or use paxolin/similar

It also states they must only be surrounded collectively by ferromagnetic material where they enter.

If it is slotted or paxolin is used then it is still a single hole in the steel!

 

[shanky887614]

It also states they must only be surrounded collectively by ferromagnetic material where they enter.

If it is slotted or paxolin is used then it is still a single hole in the steel!

you dont need to slot it for the cpc though, eddies wont affect it and if it does you have bigger problems.

that reg also says single swa cables are not allowed

 

[davesparks]

you dont need to slot it for the cpc though

Yes you do, which is the point that has been made here, and it does state it quite clearly in that regulation and I, along with others, have been corrected on in the usual helpful manner from a certain ****

 

[shanky887614]

Yes you do, which is the point that has been made here, and it does state it quite clearly in that regulation and I, along with others, have been corrected on in the usual helpful manner from a certain ****

enclosure is not the same as entry hole, take that how you will.

the reg

"the conductors of an ac circuit installed in a ferrous enclosure shall be arranged so that all line conductors and the neurral conductor, if any and the appropriate protective conductor are contained within the same enclosure"

 

[stevethesparks]

Collectively being the key word

 

[netblindpaul]

Wrong, read 521.5.1



Send your copy back & get a genuine one.



You're now saying it is allowed I think.

Firstly 521.5.1 is EXACTLY what I have been referring to, it states REQUIRED.
If it's not REQUIRED then it's NOT ALLOWED.
I have said this from the start.
You NEED to understand when it is REQUIRED, by BS7671, not just a whim.
If it's not required, then it's not allowed, so, when is it required?
Almost never if ever.

Next.
I can't send my copy back as I don't have a paper one the IET host it for me, so I am told by them that I always have the latest version, and my comments above relate to that.

So, if you check the current version of BS7671 (i.e. Amd 3), you will see that my comments relate directly to that and are not contradictory in any way.

IF you can find a reason where by a CPC has to be added to an SWA then it's fine, but, that must be by calculation just coz you want to does not count as a regulation in BS7671.
Now, IF the calculations require an additional cpc, then it is doubtful that in most cases the SWA is adequate.

I am NOT saying it's allowed, UNLESS it is REQUIRED, if you can prove it's REQUIRED then it's allowed, how often is it REQUIRED under BS7671, I would go for about 1% of installs.

 

[davesparks]

enclosure is not the same as entry hole, take that how you will

The second line states that the conductor referred to in the first line (l&n&cpc) must only be collectively surrounded by ferromagnetic material as they enter the enclosure, this translated in to English means they must pass through the same hole in a steel enclosure.

 

[davesparks]

enclosure is not the same as entry hole, take that how you will.

the reg

"the conductors of an ac circuit installed in a ferrous enclosure shall be arranged so that all line conductors and the neurral conductor, if any and the appropriate protective conductor are contained within the same enclosure"

That is only the first of three paragraphs which make up that regulation, you can't just use one third of the regulation on its own and ignore the other two thirds

 

[netblindpaul]

It will split proportionally, it will not split equally. I've read differing information on exactly what those proportions will be, with a general consensus that the majority of the fault current will flow through the armour.
I am not talking about an additional cpc, I am talking about a bond run in parallel with the armour (as cpc), this is still a protective conductor

Not according to the theory and research done by ERA, now if you know better then ERA then good on you WTF are you doing posting on an internet forum?

You cannot link a cpc and a bonding conductor terminology wise.
Is it a cpc or a bonding conductor or both.
This thread started off with regard to cpc's.
IF it's a cpc it's a cpc.
You are now trying to justify why you were wrong in the first place.

 

[netblindpaul]

It also states they must only be surrounded collectively by ferromagnetic material where they enter.

If it is slotted or paxolin is used then it is still a single hole in the steel!

Correct.

 

[davesparks]

Firstly 521.5.1 is EXACTLY what I have been referring to, it states REQUIRED.
If it's not REQUIRED then it's NOT ALLOWED.
I have said this from the start.
You NEED to understand when it is REQUIRED, by BS7671, not just a whim.
If it's not required, then it's not allowed, so, when is it required?
Almost never if ever.

Next.
I can't send my copy back as I don't have a paper one the IET host it for me, so I am told by them that I always have the latest version, and my comments above relate to that.

So, if you check the current version of BS7671 (i.e. Amd 3), you will see that my comments relate directly to that and are not contradictory in any way.

IF you can find a reason where by a CPC has to be added to an SWA then it's fine, but, that must be by calculation just coz you want to does not count as a regulation in BS7671.
Now, IF the calculations require an additional cpc, then it is doubtful that in most cases the SWA is adequate.

I am NOT saying it's allowed, UNLESS it is REQUIRED, if you can prove it's REQUIRED then it's allowed, how often is it REQUIRED under BS7671, I would go for about 1% of installs.

The regulation says protective conductor, not circuit protective conductor

 

[netblindpaul]

enclosure is not the same as entry hole, take that how you will.

the reg

"the conductors of an ac circuit installed in a ferrous enclosure shall be arranged so that all line conductors and the neurral conductor, if any and the appropriate protective conductor are contained within the same enclosure"

You have cut that quote short to try and make a point, which makes the post wrong.

 

[netblindpaul]

The second line states that the conductor referred to in the first line (l&n&cpc) must only be collectively surrounded by ferromagnetic material as they enter the enclosure, this translated in to English means they must pass through the same hole in a steel enclosure.
View attachment 29569

Correct.

 

[netblindpaul]

That is only the first of three paragraphs which make up that regulation, you can't just use one third of the regulation on its own and ignore the other two thirds

Correct, but the 3rd paragraph states REQUIRED.
When is it REQUIRED.

 

[spadge47]

I cant see how to collectively take main tails and earth all in one though, because the main bonding (water/gas) must have to go through the same holes as the tails

 

[netblindpaul]

The regulation says protective conductor, not circuit protective conductor

We are discussing circuit protective conductors.
This is where this started, and it has not changed, as I have said from the start, where it is REQUIRED.
Now you are trying to change the topic to something else to try to make it look like you were right when you were wrong.

Look the devil is in the detail, the word is REQUIRED, it it's not REQUIRED, then it has to be collectively surrounded by ferrous material.
IF it is required, then it is almost definitely not a cpc, thus not part of the original discussion, end of.

 

[netblindpaul]

I cant see how to collectively take main tails and earth all in one though, because the main bonding (water/gas) must have to go through the same holes as the tails

No because they are not part of the supply circuit supplying the power to the board.
They are BONDING conductors not cpc's.

 

[spadge47]

So are the wylex tail glands with the 2 holes only not be used then?

 

[davesparks]

We are discussing circuit protective conductors.
This is where this started, and it has not changed, as I have said from the start, where it is REQUIRED.
Now you are trying to change the topic to something else to try to make it look like you were right when you were wrong.

Look the devil is in the detail, the word is REQUIRED, it it's not REQUIRED, then it has to be collectively surrounded by ferrous material.
IF it is required, then it is almost definitely not a cpc, thus not part of the original discussion, end of.

The discussion started with an earthing conductor, which is a protective conductor which performs the functions of both cpc and main bond. I was wrong about the question, now despite your unhelpful attitude I have learned that I was wrong and think I can see why the regulation is the way it is.

 

[spadge47]

 

[Leesparkykent]

So are the wylex tail glands with the 2 holes only not be used then?

Use these Wiska TKE/B40 2X25mm+1x16mm Nickel Plated Brass Tail Kit - Edwardes

 

[netblindpaul]

Read and understand the relevant reg.
IF the 3 conductors are part of the same circuit then they must be collectively surrounded by ferrous material, unless they come under the deviation in the 3rd paragraph.
Someone has posted a pic of the book earlier, look at it, read it and understand it, then all will become clear.

 

[davesparks]

Use these Wiska TKE/B40 2X25mm+1x16mm Nickel Plated Brass Tail Kit - Edwardes

Or a regular open grommet or a bush and locknut as electricians have been doing for countless years

 

[netblindpaul]

The discussion started with an earthing conductor, which is a protective conductor which performs the functions of both cpc and main bond. I was wrong about the question, now despite your unhelpful attitude I have learned that I was wrong and think I can see why the regulation is the way it is.

Where did that come from?
Now you have me confused!

 

[spadge47]

Wylex EIU Gland Kit, Moulded For Metal Units, Fitted With RCD Isolators - John Cribb & Sons Ltd, UK Electrical Distributors, Dorset, Hampshire, Wiltshire, Somerset & the Isle of Wight.

 

[Leesparkykent]

Or a regular open grommet or a bush and locknut as electricians have been doing for countless years

Could do put personally I would use the wiska gland in domestic.

 

[andyb]

We are discussing circuit protective conductors.
This is where this started, and it has not changed, as I have said from the start, where it is REQUIRED.

No Paul, this is your post No 24

They don't allow it to enter through a different point, never have.

You slipped the 'required' red herring in later, I assume when you actually read 521.5.1

Why do you keep repeating the word 'required' it's irrelevant. You either can or you can't bring the protective conductor through a separate opening.

 

[davesparks]

Could do put personally I would use the wiska gland in domestic.

I won't, a 32mm grommet has worked fine for me in CUs since I started my apprenticeship.

 

[andyb]

Read and understand the relevant reg.
IF the 3 conductors are part of the same circuit then they must be collectively surrounded by ferrous material, unless they come under the deviation in the 3rd paragraph.
Someone has posted a pic of the book earlier, look at it, read it and understand it, then all will become clear.

You may call it a deviation, others call it reg 521.5.1 paragraph 3.

 

[Leesparkykent]

I won't, a 32mm grommet has worked fine for me in CUs since I started my apprenticeship.

Happy days! Do you have kids?

 

[davesparks]

No Paul, this is your post No 24



You slipped the 'required' red herring in later, I assume when you actually read 521.5.1

Why do you keep repeating the word 'required' it's irrelevant. You either can or you can't bring the protective conductor through a separate opening.

You can't (unless it is a protective conductor which is running in parallel with the armour of an SWA cable.)

 

[andyb]

You can't (unless it is a protective conductor which is running in parallel with the armour of an SWA cable.)

So you can then.