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Discuss Max Zs values. (20 characters) in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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So I've been told by the NICEIC not to use the 80% rule for max Zs (even though that's the table provided on the inside of the cert books). They want me to use the 100% values from table 41.3 in the BYB. Not a problem.

However I can't seem to find a table for the BS EN 3871 MCB's in there.

Anyone know where I can find one? Otherwise I guess I will have to apply a correction factor to the 80% values every time which would be a PITA.

Thanks
 
BS EN 3871: Superseded and Withdrawn. It was replaced with BS EN 60898
 
I think you mean on the testing sheet? Yeah, they do ask that. Older regs book, or I might have a cheat sheet somewhere. I’ll just check...

Edit: no it’s just got breakers and fuses on.
 
So I've been told by the NICEIC not to use the 80% rule for max Zs (even though that's the table provided on the inside of the cert books). They want me to use the 100% values from table 41.3 in the BYB. Not a problem.

However I can't seem to find a table for the BS EN 3871 MCB's in there.

Anyone know where I can find one? Otherwise I guess I will have to apply a correction factor to the 80% values every time which would be a PITA.

Thanks
You paysyer money and takes yer choice mate, do it as per the regulations.
 
Being somewhat pedantic if they wish you to use the values from a specific table in BS7671 and that table does not have values in it for common protective devices then I would say they need to provide you with more accurate information.
To do otherwise would be the height of unprofessionalism; for the NICEIC to apply impossible demands of people who are paying them to do a job?

Anyway Stroma produced this table at the time of the amendment that includes BS3871 (but remember it is not the table you have been asked to use!).
 

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I always thought it funny that ms Clancy wanted 100% values but then she printed the 80% values in the EIC book. A bit bizarre, sure they'll have their reasons, not die they'll be logical.
 
Being somewhat pedantic if they wish you to use the values from a specific table in BS7671 and that table does not have values in it for common protective devices then I would say they need to provide you with more accurate information.
To do otherwise would be the height of unprofessionalism; for the NICEIC to apply impossible demands of people who are paying them to do a job?

Anyway Stroma produced this table at the time of the amendment that includes BS3871 (but remember it is not the table you have been asked to use!).
I always thought it funny that ms Clancy wanted 100% values but then she printed the 80% values in the EIC book. A bit bizarre, sure they'll have their reasons, not die they'll be logical.
Emma Clancy and Logic don't compute HT
 
100 percent zs values should be used as this is the circuit worst case scenario when operating at its maximum temperature of 70 degrees.
The printed 80 percent values are just guidance to the tester.
If the circuit is over the 80 % value given then it will be over the maximum given in the tables in bs7671 at 70 degrees.
This is the maximum zs value.
 
So I've been told by the NICEIC not to use the 80% rule for max Zs (even though that's the table provided on the inside of the cert books). They want me to use the 100% values from table 41.3 in the BYB. Not a problem.

However I can't seem to find a table for the BS EN 3871 MCB's in there.

Anyone know where I can find one? Otherwise I guess I will have to apply a correction factor to the 80% values every time which would be a PITA.

Thanks
Try dividing by 4 and multiplying by 5........100%:cool:
 

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