BS 7671 17th Edition Wiring Regulations - Amendment 2 ?

[GLAES LTD]

Hi,

I was just talking to a client today and he said he heard that this year we will have the second amendment for the BS 7671.He also said that the third amendment is already being planned for 2015. Do you know anything about it?

I had enough about upgrading the books I have.

Thank you!

 

[Engineer54]

I thought the bgb temps were based at 80 degrees and the osg at 10 degrees. I would say a foundry is considerably more than 10 degrees lol

Seems you still have an awful lot to learn!!

 

[Engineer54]

It's another derating factor so whatever anyone is using to work out max Zs at present it will need to be applied if you wish to work to 7671.

Thankfully i can still think for myself, and don't need a wire by picture book to access an appropriate Zs value to apply to a circuit.

 

[Silly Sausage]

...and you're still driving the same van around....

Like Fred Flintstone's motor.

 

[Knobhead]

when me, tony,pete999, and geordiespark started, the book was written in latin

You got an ironic THANKS!

The annoying thing is, I left the brown (parchment) copy of the 14[SUP]th[/SUP] at work when I retired. I think it was amendment 2 1974-76.

 

[pitkin2020]

Seems you still have an awful lot to learn!!

The tables in BS7671 give maximum loop values for conductor temperatures of 70[SUP]o[/SUP]c.
Tables in guidance note 3 and the OSG give values for conductor temperatures of 10[SUP]o[/SUP]c.
A measured Zs value is not directly comparable with the tables in BS7671 as in theory temperature readings would have to be taken at the time of testing and correction factors applied.
In practice a rule of thumb has been applied which says the measured value should not exceed 85% of the tabulated value in BS7671. Tables in the OSG and guidance note 3 have already been adjusted.

Whats wrong with that exactly as that is directly from last weeks notes at college??

 

[Engineer54]

In practice a rule of thumb has been applied which says the measured value should not exceed 85% of the tabulated value in BS7671. Tables in the OSG and guidance note 3 have already been adjusted.

Why not teach the how, why and when to adjust Zs values to environmental conditions like we were, rather than give bukshee coverall values?? As i think i stated, i've never used the OSG Zs value tables, and have no intention of doing so in the future....

So i'll ask again where were all these de-rating factors for Zs values for the last 40 odd or so years that seem to be now, oh so important?? To me, it seems basically all about fixing something that doesn't need to be fixed!! Or is it all about making the values of Zs ridiculously low to promote/increase the use of RCD devices in place of conventional ADS protection....

 

[pitkin2020]

It is still taught but the figures are quoted in the books are set at the temps quoted

 

[Deleted member 26818]

We had to lower maximum Zs figures because our voltage went down.

 

[ImpededLoop]

We had to lower maximum Zs figures because our voltage went down.

So in the case of an EICR would you be wrong to apply the maximum Zs at the measured voltage rather than the mythical 220V?

 

[Deleted member 26818]

Yes and No.
There's no definitive answer to such a question.
It's something that the individual conducting the EICR will have to decide.

 

[Evy]

Anybody heard anything about changing the definition of a competent/instructed person. Also red protection being a must for sockets under 20amp in factory's ect where it wasn't a must due to competent person ect? Thx

 

[Evy]

Rcd sorry not red lol

 

[Engineer54]

We had to lower maximum Zs figures because our voltage went down.

So Zs values were/are changed to accommodate a make believe nominal voltage of 400/230 volts, while still being supplied with the Real nominal voltage of 415/240 volts?? Well that just about sums up just how bloody stupid things have gotten.... Life in the new Mythical World!! lol!!