Ze in BRB

[brucegenerator]

Could any one tell me which page or chapter to find maximum Ze of circuit breakers please in BRB?

 

[Spudnik]

Im assuming you mean Zs?

 

[Deleted member 9648]

The Ze is the earth loop impedance external to the installation,if you mean Zs they can be found on p48-9

 

[topquark]

If you mean max Zs, starts around page 48 from memory, but make sure you use the correct table for device/earthing system.

 

[brucegenerator]

Zs is the one is it table 41 page ?cheers!

 

[pushrod]

Zs is the one is it table 41 page ?cheers!

There is no table 41 by itself, only 41.1 , 41.2, 41.3, etc etc. Regarding Ze there are only 3 max values of any relevance

tn-c-s - 0.35 ohms

tn-s - 0.8 ohms

and TT - more confusingly a max of 21 ohm for the distributor's earth electrode , with the consumer's earth electrode being as low as possible. A figure of 200+ ohms is considered to be unstable and 100 ohms is often considered to be the max acceptable. Page 11 of the OSG shows this.
Table 41.5 of the BRB shows Zs for values for rcd operation in final circuits not exceeding 32A

 

[ezzzekiel]

Biography 36 YEARS OLD,UNEMPLOYED 17TH EDITION ELECTRICIAN yet cant find zs values in bible?

 

[brucegenerator]

Never felt the need to fork out 50 bucks for something i would hardly use .Just needed the page number for my 2391 practical.That is all.Got the GN3 ANYWAY.

 

[ezzzekiel]

Cant see how any "electrician" manages without a copy of regs, and gn3 covers i&t only not regulations to work to

 

[Guest123]

Never felt the need to fork out 50 bucks for something i would hardly use.

Know it all then do you????

If you do go self employed and indeed join a Part P scheme, you will HAVE to have one as it is a requirement by some.

 

[ezzzekiel]

find myself costantly refering to bs7671 and osg, even on standard installations i cover every day, for zs values that are mentioned for a start.

And as lenny state all competent per schemes require you to hold a copy.

 

[Sintra]

I can't see how anyone can carry out installation work to comply with bs 7671 if they don't have a copy.

Except rain man possibly.

 

[stretchyboy]

Except rain man possibly.

He's too busy working out who's on first base

 

[Des 56]

The regs nowadays apear to contain information on what complies,but little in the way of how to comply

In the past it was "thou shalt do this" and "thou shalt do that"and working out for yourself was minimal

To apply the regs to installations present day,a person needs to continually refer to those regs to see if what he proposes conforms to whats required
I realise how tight money can be, but not owning or wanting a brb,even if you have many years in the trade, it is surprising, and as posted,it is a requirement if you were to join any of the schemes,so may be worth an investment by yourself

 

[stretchyboy]

I cant remember them ever saying what to do, only what not to do and thats the 15th/16th and 17th. Thats why we have the OSG. But I agree with your point that it is always worth having it to refer to, as you cant beat the 'real' regulation wording rather than the OSG version. You cant always get the right flavour of the Regs with the Guide in some instances.