High Zs values (Just)

[telectrix]

not often. last time was a 16mm T/E running @ 100A. it reached 40 deg.C. after 30 minutes when the 63A MCB tripped. that's the sheath temp, conductors probably a bit warmer.

 

[davesparks]

not often. last time was a 16mm T/E running @ 100A. it reached 40 deg.C. after 30 minutes when the 63A MCB tripped. that's the sheath temp, conductors probably a bit warmer.

Exactly, not often, hardly a good sample size to make a conclusion about every cable in every installation in the country.

 

[Intoelectrics]

Exactly, not often, hardly a good sample size to make a conclusion about every cable in every installation in the country.

I have often come across cables that are worryingly hot during normal service. Though I have not actually measured the temperature of many some have been too hot to touch. I'd say (depending on the install) temperature is a very serious factor to consider when doing an install.

 

[telectrix]

Exactly, not often, hardly a good sample size to make a conclusion about every cable in every installation in the country.

i agree, mainly in industrial situations, but generally, cables are underrated by the BS7671 to err on the side of safety, espin the domestic sector where cables are rarely pushed anywhere near their rated capability.

 

[Deleted member 9648]

Not all non-compliances with current 7671 will attract a code 2. For example the recommended code for a cable buried at <50mm deep without RCD protection and compliant with recent previous editions of 7671 is a code 3.

Compliance with previous editions, recent or not, does not affect the code given.
The code given is in accordance with the current edition.

The post you have quoted clearly states that codes are allocated according to the current edition of 7671, I have not suggested otherwise.
But my interpretation of a code 3 issue is one that does not comply with current 7671 but in the opinion of the inspector does not compromise the overall safety of the installation. I'm still waiting for Essex to explain his interpretation to me.
We are also advised that when carrying out an EICR consideration must be given to the fact that an installation complied with Bs7671 at the time it was installed. For example for an installation wired in the last (say) 20 yrs, lack of RCD protection to socket outlets not likely to supply equipment outdoors would attract a code 3, not a code 2.
I am still not persuaded that a zs reading which was compliant 3 years ago is now potentially dangerous.

 

[plugsandsparks]

It clearly isn't dangerous and i am at a loss understanding the need to introduce it, there is obviously a downside as cabling and distribution costs will obviously rise, breakers will be much more on the limit of the load and may cause nuisance tripping, so balance this against an install that might only have 220V and simultaneously have a short cct fault. Since i have never measured this voltage on any of the commercial and industrial installation for the last 10 years, i am at a loss to why this obviously costly reg was introduced.

 

[Nigel]

The post you have quoted clearly states that codes are allocated according to the current edition of 7671, I have not suggested otherwise.
But my interpretation of a code 3 issue is one that does not comply with current 7671 but in the opinion of the inspector does not compromise the overall safety of the installation. I'm still waiting for Essex to explain his interpretation to me.
We are also advised that when carrying out an EICR consideration must be given to the fact that an installation complied with Bs7671 at the time it was installed. For example for an installation wired in the last (say) 20 yrs, lack of RCD protection to socket outlets not likely to supply equipment outdoors would attract a code 3, not a code 2.
I am still not persuaded that a zs reading which was compliant 3 years ago is now potentially dangerous.

It is really very simple. A c3 is an issue that is not dangerous if left but could be improved using the current Edition of 7671 as a guide.

So anything that is not done to 7671 but is not classed a C1 or a C2 would be a C3.

 

[Deleted member 9648]

Er...that explanation looks pretty much the same as mine

 

[Nigel]

Er...that explanation looks pretty much the same as mine

It read as if you were saying if it meets a previuos version of 7671 then you would no code it.

 

[Deleted member 9648]

It read as if you were saying if it meets a previuos version of 7671 then you would no code it.

Ok, wasnt what I meant,