indeed thanks for the links with the diagrams - and there well may be better examples of well reasoned technical judgements, it just happens I worked alongside Aubrey Sandman (the Plaintiff) at one point about 30 years ago, and so I was more than glancingly familiar with the case. It is also the reason that I will put my initials and a date onto any diagrams I do that I consider important.

The very candid bits I liked were..
... I believe that diagrams of this sort are not readily comprehensible to those who have no experience of them and their interpretation. In effect, they show the interconnection of various electronic components ...

(where perhaps Mr Justice Pumfrey is also finding things not 'readily comprehensible' )and later in regard to how much one circuit is identical to another if the connectivity is the same, but redrawn so the layout changes

.... I have felt considerable doubt over this aspect of the case and my opinion changed more than once in the course of the argument, but in the result I have come to the conclusion that ......

(it is indeed a copy)

Mike.

PS Panasonic lost the court case, but Dr Sandman lost the war, in that Panasonic kept making and the amplifiers without any compensation to him. .....

Next one.. AFDDs. Looks like there's a change from High Risk Residential Buildings to Higher-risk buildings (innocuous enough of itself as the definition seems to be similar (18m or 7 storeys and containing 2+ residential units) but the actual definition is indirected to the Building Safety Act and "The Secretary of State may by regulations make provision supplementing this section.". Does this mean than BS 7671 has become "ambulatory"

Actually, having re-read it again, I think I might have been mistaken. I'd read the bit about the Building Safety Act 2022 and seen the bit in that (where it defined what a HRB was) allowed "The Secretary of State may by regulations make provision supplementing this section." (which seemed to make it ambulatory) - but I hadn't cottoned on that the next bit "Supplementary Provisions Regulations 2023" in effectively referred to what the Secretary of state could do, and locked it down to one existing version. Mea culpa. Apologies for the confusion.

   - Andy.

mapj1 said:

PS Panasonic lost the court case, but Dr Sandman lost the war, in that Panasonic kept making and the amplifiers without any compensation to him. .....

I expect that he could not afford the considerable legal cost of claiming royalties. No conditional fee arrangements in those days!

Has anyone figured out what the new version of 433.3.1 is all about?

It's confusing me... it's under the heading of 'omission of devices for protection from overload' but it reads as if it's about the position of such devices, not their omission (i.e. it looks like a rewrite of 433.2.2 but it's been put under 433.3.1). Some of the new re-wording seems a bit vague to me too - e.g. what's "Where automatic disconnection of supply is inappropriate" meant to mean in this context?

and why "(c) A device for protection against overload need not be provided for circuits for telecommunications, control, signalling and the like." - what's the idea behind that? Some will be safe enough because the source won't be able to supply excess current (or will just shutdown), but some control circuits are mains derived or from substantial sources, and I would have thought could pose a fire risk if overloaded (e.g. if someone plugs in too many phones or PoE devices or replaces a lamp with the wrong rating) - a blanket "don't bother" seems a bit flippant...

   - Andy.

(edited to remove erroneous talk of faults)

AJJewsbury said:

and why "(c) A device for protection against overload need not be provided for circuits for telecommunications, control, signalling and the like." - what's the idea behind that? Some will be safe enough because the source won't be able to supply excess current (or will just shutdown), but some control circuits are mains derived or from substantial sources, and I would have thought could pose a fire risk if overloaded (e.g. if someone plugs in too many phones or PoE devices or replaces a lamp with the wrong rating) - a blanket "don't bother" seems a bit flippant...

I would hope that would be covered by the relevant equipment standards.  For example, a PoE adaptorshouldn't catch fire if you connect too many pieces of equipment to it.

For example, a PoE adaptorshouldn't catch fire if you connect too many pieces of equipment to it.

Indeed - which used to be covered by the "characteristics of the load or supply" clause - which seems simple and safe - and useful for many situations - but they seem to have removed that option and replaced it will an assumption that " telecommunications, control, signalling and the like" will never need overload protection and everything else will - which feels a bit blinkered.

   - Andy.

Well you could read that that the boiler heating control wiring, which in a traditional arrangement are 'mains level logic' now need not have ADS except an RCD direct off the 100a main supply fuse, and I suspect that meaning is NOT intended.

Mike.

gkenyon said:

only a court can interpret a Standard

I happened to work with a barrister today who does regulatory work. This includes issues of compliance with building regulations. If I understood him correctly, courts would not normally get down into the weeds where standards are concerned. Essentially, unless there is a very good reason to suspect fraud, if there is an EIC, the installation complies with BS 7671.

Next one... does anyone know exactly what the "N750" designation for underground ducts mean? So far I've only gathered that 750 means 750 Newtons for crush resistance (over what sort of area I can't tell - if it were per mm² like concrete blocks that would be quite impressive, if it's over a much larger area, then maybe it won't necessarily cope with even me standing on it with one foot). "N" seems to be impact resistance of "normal" ... which doesn't tell much much as all.

As you might have noticed there's a suggestion in 522.8.10 that N750 duct will provide the equivalent protection as earthed armour ... which I'm a little doubtful of so far,

   - Andy.

Andy,

Im sure you know some of this already, N450 Ducts under footpaths etc, N750 under roadways. Standard would be BS EN 61386-24:2010 and from what I can find testing is carried out and marking of duct as per the following;

" Corrugated cable conduits 450N and 750N are manufactured and tested in accordance with EN 61386-1 and EN 61386-24. With reference to these standards, each European country issues its own product marking:  Cable Conduit Pipes are manufactured in accordance with the “Directive 2014/35/EU relating to electrical equipment designed for use within certain voltage limits” and CE-marked, so they do not fall under the ‘Construction Products Regulation’ nr. 305/2011.

Cable conduits must be identified with a durable and legible marking applied to the surface of the conduit every 1 to 3 metres.

The marking in accordance with EN 61386-1 and EN 61386-24 must contain the following information:

• manufacturer’s name
• nominal diameter
• the letter N (normal type)
• the normative reference
• the certification body marking (e.g. IEMMEQU)
• date of production
• crushing resistance (450N or 750N)

The tests required by the above-mentioned standards and often stated in the corrugated pipe data sheet are:

• compressive strength (450N or 750N);
• impact resistance (L or N series);
• resistance to bending: foldable or flexible;
• resistance to penetration by solids and liquids: IP protection rating according to IEC EN 60529.

The main characteristics for the choice of corrugated pipe for regulation electrical installation are resistance to compression and impact.

Compressive strength is the most important characteristic since the pipe is buried and consequently subjected to the overlying static load. On top of this there may also be any load due to above-ground stresses such as the weight of vehicles. As defined by the standard, the corrugated cable conduit sample is crushed between two plates so as to deform the inside diameter by 5%; the force required to achieve this crushing must exceed 450N or 750N.

 While compressive strength is a property that accompanies the Cable Conduit during its life, the impact test, on the other hand, serves to guarantee the duct during installation. The test simulates the accidental stresses caused by stones in the ground falling onto the surface of the structure during the burial phase. Therefore, the soil layer adjacent to the cable conduit should be free of stones larger than 80-100 mm in diameter. To test this characteristic, the sample, conditioned for 2 hours at -5°C, is hit by a dart with a fixed weight of 5 kg from a variable drop height depending on the nominal diameter of the corrugated pipes (300 to 800 mm height). At the end of the test, there must be no gap allowing water to pass from the inside to the outside."

Hope that helps a little.

Cheers GTB