Best Practice Guide No 4 Issue 7

[binky]

There is no absolute requirement in BS7671 for fault protection to be provided by an RCD. Whilst I understand this is the most logical solution it is not quoted as such.

I don't think anyone has invented any other way of meeting the requirements, except perhaps gear for IT systems ie hospitals. Typical regs writing, it leaves the door open for options other than RCDs, should they exist, but in reality, it's RCDs all the way.

 

[kerching]

Sir Kerching, I have to assume you are several of these, (or equivalent lubrications), ahead of me and I am truly humbled by my poor performance......!!
View attachment 16536
But.... I do not believe that "C4" did exist??

New observations are "C1", "C2", "C3", "FI"
Whereas the old identifications were just "1", "2", "3", "4"

Obviously I may be too intoximacated to be right ???
and open to correction?

You can prove anything with facts

 

[Murdoch]

I am not pulling you down but your continual criticism of BS7671 may be retarded if you actually made an effort to understand it, your retort to me in #10 highlights your lack of understanding because fault protection by way of an RCD is not an absolute

I give up with your views.

BS 7671 is written and structured in such a way that its far too complex and lacks a fair amount of clarity.

No wonder so many customers are up in arms about being ripped off by sparks because seemingly few people seem to understand it and thats what really bugs me.

K
I
S
S

A customer last week had the following question

Old wylex board, no RCD

spark 1 - no comment
Spark 2 - C2
Spark 3 - C3


So who's correct?


BS3036 with no RCD is a C2 in my book

 

[ProDave]

I give up with your views.

BS 7671 is written and structured in such a way that its far too complex and lacks a fair amount of clarity.

No wonder so many customers are up in arms about being ripped off by sparks because seemingly few people seem to understand it and thats what really bugs me.

K
I
S
S

A customer last week had the following question

Old wylex board, no RCD

spark 1 - no comment
Spark 2 - C2
Spark 3 - C3


So who's correct?


BS3036 with no RCD is a C2 in my book

But this edition of the guide says 3036 with no RCD is C3. there may be other issues with an old instalation which makes it a C2 but not just being a 3036 with no RCD.


If you say it is a C2 just for being a 3036 with no RCD then you are just the same as those saying a plastic CU is C2 and needs replacing.

 

[Fleeting]

I give up with your views.

BS 7671 is written and structured in such a way that its far too complex and lacks a fair amount of clarity.

No wonder so many customers are up in arms about being ripped off by sparks because seemingly few people seem to understand it and thats what really bugs me.

K
I
S
S

A customer last week had the following question

Old wylex board, no RCD

spark 1 - no comment
Spark 2 - C2
Spark 3 - C3


So who's correct?


BS3036 with no RCD is a C2 in my book

You are forever moaning, it isn't structured in a way to make it complex or unclear.
It isn't uncommon for people to assume RCDs are a must for TT systems and I agree it is the most logical approach however, BS7671 gives two options but does state it is the preferred method (RCD) but nevertheless it is not an absolute. Here it is to save to looking through such a complexity of print.

 

[Fleeting]

I give up with your views.

BS 7671 is written and structured in such a way that its far too complex and lacks a fair amount of clarity.

No wonder so many customers are up in arms about being ripped off by sparks because seemingly few people seem to understand it and thats what really bugs me.

K
I
S
S

A customer last week had the following question

Old wylex board, no RCD

spark 1 - no comment
Spark 2 - C2
Spark 3 - C3


So who's correct?


BS3036 with no RCD is a C2 in my book

Why is a BS3036 fuse any different to an mcb when considering RCD protection?

 

[Murdoch]

Why is a BS3036 fuse any different to an mcb when considering RCD protection?

I said I’ve given up on your views

You never offer up your opinion except to criticise others

Let’s go back to the 15 th edition then

 

[UNG]

You are forever moaning, it isn't structured in a way to make it complex or unclear.
It isn't uncommon for people to assume RCDs are a must for TT systems and I agree it is the most logical approach however, BS7671 gives two options but does state it is the preferred method (RCD) but nevertheless it is not an absolute. Here it is to save to looking through such a complexity of print.View attachment 16542

With reference to note 1

Why is a BS3036 fuse any different to an mcb when considering RCD protection?

You can't put the wrong size fuse wire in an MCB when it trips, someone replacing the the wire in a 3036 carrier could easily replace it with any bit of wire they have lying around without any consideration for the Zs value

The problem these days to some extent you have to protect people from their own stupidity which is something that is not clearly stated in 7671

 

[binky]

You are forever moaning, it isn't structured in a way to make it complex or unclear.
It isn't uncommon for people to assume RCDs are a must for TT systems and I agree it is the most logical approach however, BS7671 gives two options but does state it is the preferred method (RCD) but nevertheless it is not an absolute. Here it is to save to looking through such a complexity of print.View attachment 16542

Ah yes, I had forgotten about note 1, I somehow doubt many TT systems would meet that requirement though, and we still have the requirement for RCD protection of sockets, but that is not retrospective fir older systems.

 

[binky]

With reference to note 1

You can't put the wrong size fuse wire in an MCB when it trips, someone replacing the the wire in a 3036 carrier could easily replace it with any bit of wire they have lying around without any consideration for the Zs value

The problem these days to some extent you have to protect people from their own stupidity which is something that is not clearly stated in 7671

I agree with what you are saying, but that still doesn't preclude rewirable fused as acceptable protective devices. I wouldn't want to be fitting any these days, but you could.

 

[UNG]

I agree with what you are saying, but that still doesn't preclude rewirable fused as acceptable protective devices. I wouldn't want to be fitting any these days, but you could.

I never said it didn't, I was pointing out how easily the designed characteristics of a cicuit could easily be altered and possibly put people at risk

 

[Murdoch]

In sorry but RCD protection for sockets goes back over 20 years and multiple versions of the regs

 

[ProDave]

In sorry but RCD protection for sockets goes back over 20 years and multiple versions of the regs

Yes of course they have, but updates to regs are not retrospective and this guidance note makes that clear.

If you want to deviate from the guidance note and give it a C2 even if they are not used for outside equipment, then feel free. I prefer to let the guidance note guide me.

 

[Murdoch]

Yes of course they have, but updates to regs are not retrospective and this guidance note makes that clear.

If you want to deviate from the guidance note and give it a C2 even if they are not used for outside equipment, then feel free. I prefer to let the guidance note guide me.

I do wonder if Napit will update their code breakers book as they have had sockets no RCD as a C2 for a very long time !

 

[binky]

In sorry but RCD protection for sockets goes back over 20 years and multiple versions of the regs

Yes, but there's plenty of very old electrical systems around, and as Fleeting correctly points out RCDs are not a definitive requirement in TT systems, although I've never seen any guidance on how you meet the requirements for not having them or a VOELD. I think in reality, it's almost impossible to meet requirements for TT without RCDs due to the resistance of the rod. Will have to do some googling into that, as it's not something I fully understand.

 

[binky]

so a bit of googling later and this is the only article I can find on TT without RCDs

https://the-regs.co.uk/blog/?p=245

 

[UNG]

so a bit of googling later and this is the only article I can find on TT without RCDs

https://the-regs.co.uk/blog/?p=245

For someone calling himself the Regs Guy it is not a good or well written piece

He make reference to a fuse but no mention to type / spec of the fuse or whether the fuse will provide close or coarse excess current protection

 

[UNG]

One thing with earth rods is you can get a good and perfectly sound reading today but what about next week, next month or several months down the line what will the reading be then, will it still be acceptable if we get no rain for a few weeks and some exceptionally warm weather to dry the ground out
What is an acceptable reading in the winter may be totally different and not compliant in a warm summer period, how would you explain that if an incident occurs
Installing earth rods is a little more onerous than just picking up a rod from the wholesalers and knocking it into the ground

 

[Fleeting]

I think we are all agreed an RCD is the preferred method for fault protection due the the probable unstable Ze from a TT system. I merely pointed out BS7671 does not make this an absolute requirement like most electricians believe.

 

[binky]

One thing with earth rods is you can get a good and perfectly sound reading today but what about next week, next month or several months down the line what will the reading be then, will it still be acceptable if we get no rain for a few weeks and some exceptionally warm weather to dry the ground out
What is an acceptable reading in the winter may be totally different and not compliant in a warm summer period, how would you explain that if an incident occurs
Installing earth rods is a little more onerous than just picking up a rod from the wholesalers and knocking it into the ground

The magic words is the regs is , "permanently and reliably assured", as we have no real means of doing that without installing some form of monitoring it really rules out not using RCDs on TT. But it's still interesting that it's an option, even if none of us would really consider it.