BS7671 history and the future?...

[M107]

OK, lets start here.

Who has gone through the 18th DPC?

Next, who commented?

I will be honest I took a look & gave the link out at the wholesalers, most who I spoke to thought it had been written in such a way that readers got bored & gave up.....

Until I gave the link nobody at the counter had any idea where to get details or even knew they had the opportunity to comment, most gave it the "decision has already been made so why would we get listened to?" unfortunately at the bottom of the electrical trade pile, trust of the governing bodies (no matter who they are) & changes they impose is non existent.

As for the slide show .............excellent & in my opinion should be passed round wholesalers & displayed on a monitor on the trade counters!

 

[Sidewinder]

OK, the DPC was very difficult to comment on, yes, very, very.

The decisions are not made when the DPC is published, they are made after.

There was no way to comment on the download, it was an online system, which was very, very poor.

I am speaking at an IET/BSI conference in a couple of weeks, and I will I can assure you be making a point about the difficulties that were experienced.

As far as the failure of installations.

One of the requirements is to "drop a rod" at the origin of all installations, easy to do, so why not...

THe issue will come on how that is worded, don't forget, we are technically not allowed to do any changes unless earthing and bonding is up to scratch.

If the earth rod requirement becomes compulsory, then to add a socket at a dwelling would require all of the earthing and bonding being upgraded, and a rod being dropped at the origin.

Also, it could become a C2 in ESF guidance, which then makes it very difficult for us to ignore the situation because the ESF guidance is backed by all the schemes, the IET, HSE, etc. etc., basically we need to follow it unless we can really justify why we don't because if the excrement hits the rotating air movement device then this document would be one of those used in court.

 

[ProDave]

Okay, so we may have to bang a rod in at every job.

Is THAT the reason this guy thinks every install will fail an EICR? If so not hard to make it pass?

It is really starting to bug me, I want to know WHY he made that statement about every install failing an EICR?

 

[Rob_the_rich]

here is the proposed reg again

542.1.201 The main earthing terminal shall be connected with Earth by one of the methods described in Regulations 542.1.2.1 to 3, as appropriate to the type of system of which the installation is to form a part and in compliance with Regulations 542.1.3.1 and 542.1.3.2. Additionally, there shall be an earth electrode, supplementing any earthing facility provided by the distributor, in accordance with one of the requirements of Regulation 542.2.3, to prevent the appearance of a dangerous touch voltage in the event of the loss of the main connection to Earth. NOTE: Refer to Part 2 and Appendix 9 for definitions of systems.

in TT systems this may mean putting in an additional rod, since even though the distributor does not provide an earth, the requirement is to prevent the dangerous touch voltage, and the main connection to earth is to the original rod.

Also, without doing the calcs, the limiting factor is not the disconnection time (as in ADS), but limiting the voltage appearing on earthing conductors under fault conditions to under 50V, during loss of main earthing. A 2 fault scenario. The resistance of the additional rod would need to be extremely low, perhaps impossibly so.

Have I got this right?

 

[Phoenix]

I note the proposed requirement to RCD protect all domestic lighting cirucits, I'd be interested in the logic behind that one, considering most will be caught anyway with the requirement from the 17th to RCD protect concealed cables. So that leaves very few instances where the reg will actually change anything and most of them are probably where there was a delibriate attempt to install in a way that didn't need RCD protection. What is the problem its trying to solve? anyone know?. Would have been better surely, to require all BC lamp holders to be of the safety type thats widely available these days.

I better get my house re-wire finished and certificated before I have to RCD protect the garage lights wired in galv conduit, or other cirucits which don't currently need it (yes, i know there will be a execption for installations designed before the implimentation date..... but leave it too long and it'll raise eyebrows about how credible the design date is, even if it is honest!)

 

[Rob_the_rich]

and what about existing lighting circuits with no cpcs? What would be the point?

 

[Lurch]

and what about existing lighting circuits with no cpcs? What would be the point?

Huh? RCDs don't need an earth connection to work.

 

[Rob_the_rich]

Huh? RCDs don't need an earth connection to work.

Oh yes, quite right.

 

[Lurch]

The resistance of the additional rod would need to be extremely low, perhaps impossibly so.

The extra rod would only need to be TT levels of resistance, as in if you lost supplier earth your installation is now a TT.

I note the proposed requirement to RCD protect all domestic lighting cirucits, I'd be interested in the logic behind that one

I assumed that was because of the above, all installations effectively now need to be treated as TT due to the rod and possible supplier earth failure protection.

Not sure why they are doing this though, or what they are expecting it to achieve, not really seen any explanations as per usual.

 

[Blue Duck]

I'm on the 18th floor of a tower block where do I bang the rod in? 

 

[ProDave]

The extra rod would only need to be TT levels of resistance, as in if you lost supplier earth your installation is now a TT.

I assumed that was because of the above, all installations effectively now need to be treated as TT due to the rod and possible supplier earth failure protection.

Not sure why they are doing this though, or what they are expecting it to achieve, not really seen any explanations as per usual.

but isn't the concern that with TNCS, you loose the supplier earth, you bave also lost the supplier neutral as well?

 

[Lurch]

but isn't the concern that with TNCS, you loose the supplier earth, you bave also lost the supplier neutral as well?

This is why I don't really understand what they are trying to achieve, they say supplier earth, but PEN is not supplier earth. PEN is PEN, earth is earth.

 

[ProDave]

I'm on the 18th floor of a tower block where do I bang the rod in? 

 

[Sidewinder]

I just picked the earth rod reg from many.

The requirement for the supplementary electrode may well be that it must be <20 Ohms, it is still under debate I believe, it may end up needing to be <1 Ohm.

There are many others to pick from that could end up C2'ing an install.

Also it is just going to drive work away from the legitimate guys because of the extra work that they have to do to comply.

The additional rod is to mitigate against the loss of a PEN conductor and divertd N currents, again it has not been well thought through.

 

[Phoenix]

I assumed that was because of the above, all installations effectively now need to be treated as TT due to the rod and possible supplier earth failure protection.

Why just lighting circuits then? If I have a circuit that just does smoke detectors (might have to go upto 1.5mm² though... thanks table 52.3)  , I can leave that off RCD, but if I add a light to it, I can't.

What about fixed equipment? mostly on migh bigger breakers than a B6?

A cynical person would think its in there because very few people are going to object to it, almost everyone puts dual RCD boards in domestic anyway, and when they don't, the ltg generally goes on an RCBO anyway, there are very few cases where its going to have an effect. A few admendments, or in the 19th, it creeps and catches commericial as well, justified by some impressive looking but difficult to confirm figures on reductions of number of fires in domestic..... and then the switchgear manufacturers really start to  see the increased sales

 

[ProDave]

I just picked the earth rod reg from many.

The requirement for the supplementary electrode may well be that it must be <20 Ohms, it is still under debate I believe, it may end up needing to be <1 Ohm.

There are many others to pick from that could end up C2'ing an install.

But are you saying an install fully complaint with 17th Amd 3, when tested after the 18th comes into force, would get a C2 for no suplimentary rod?  i.e .are you saying the 18th regs will apply retrospectively to an older install?

 

[Phoenix]

There are many others to pick from that could end up C2'ing an install.

Can you really justify applying a C2 to anything that was perfectly acceptable installation practice only a few years back?

Now I'm perhaps one of the younger ones here (I qualified right at the tail end of the 16th edition being current), I'd struggle to justify anything that was acceptable while I was in the trade as being a C2...I understand that this mind set is going to have to change as I get older, as if the older members here went by the same thing, we wouldn't be giving C2 to lack of 30Ma RCD to sockets intended for outside use, etc.... so where do you draw the line.... 15 years since it was acceptable practice? 20? 25? 30?

 

[Lurch]

A cynical person would think its in there because very few people are going to object to it, almost everyone puts dual RCD boards in domestic anyway, and when they don't, the ltg generally goes on an RCBO anyway, there are very few cases where its going to have an effect. A few admendments, or in the 19th, it creeps and catches commericial as well, justified by some impressive looking but difficult to confirm figures on reductions of number of fires in domestic..... and then the switchgear manufacturers really start to  see the increased sales

This is the problem, there is a very large gap between the people doing the work and people making the rules. Some people seem to think there isn't and that we are working as one, we aren't. It is very much 'us and them'

so where do you draw the line.... 15 years since it was acceptable practice? 20? 25? 30?

This is where it comes down to experience and risk assessing the installation. Unfortunately a lot fo this has been taken away from us and we are getting very much like the American way of doing it (this wire goes here, this socket goes on one end, this OCPD on the other etc).

As I have said many times it is in a downward spiral and it isn't going to stop, no matter how many people try and change it (unless literally everyone in the industry stopped, but that isn't going to happen). These rules are being made fr the worst case scenario, i.e. Joey Thicko ex-milkman the new approved registered electrician doing electrical work even though he has no common sense or technical skills.

 

[Phoenix]

Agree - The problem is if you start to put C2s for things that were acceptable only a year before last, you detract from the C2s for the the things that really should be sorted out, the lack of earthing to class 1 flouro battens, or the taped up connector blocks above the ceiling grid, so what do you do then... start to make some of them C1? Then you really detract from the things that are really dangerous that the client needs to sit up and take notice about! I did an I&T recently where there were things where I had to carry out some basic temporary repairs to some code 1 items concerning exposed live parts, where the first thought was "How has someone not got a shock off that?"

 

[Murdoch]

Oh yes, quite right.

They don't need a fault to earth or neutral to work either

Agree - The problem is if you start to put C2s for things that were acceptable only a year before last, you detract from the C2s for the the things that really should be sorted out, the lack of earthing to class 1 flouro battens, or the taped up connector blocks above the ceiling grid, so what do you do then... start to make some of them C1? Then you really detract from the things that are really dangerous that the client needs to sit up and take notice about! I did an I&T recently where there were things where I had to carry out some basic temporary repairs to some code 1 items concerning exposed live parts, where the first thought was "How has someone not got a shock off that?"

Yup

I thought the old 1 - 4 was a more sensible approach...