Max Zs values. (20 characters)

[Zdb]

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

 

[Spoon]

BS EN 3871: Superseded and Withdrawn. It was replaced with BS EN 60898

 

[hightower]

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.

 

[Andy78]

Current values for BS EN 60898 and BS EN 61009 are also relevant to BS 3871

 

[Pete999]

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.

 

[Richard Burns]

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!).

 

[hightower]

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.

 

[Pete999]

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

 

[Ian1981]

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.

 

[Zdb]

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!).

Perfect. I think that's exactly what i was looking for.

Thanks

 

[Toneyz]

You paysyer money and takes yer choice mate, do it as per the regulations.

Did you not have something from stroma once Pete?
Sorry just noticed Richard Burns has attached to his post.

 

[Pete999]

Did you not have something from stroma once Pete?
Sorry just noticed Richard Burns has attached to his post.

Yes I did Mate

 

[ipf]

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%

 

[Richard Burns]

Try dividing by 4 and multiplying by 5........100%

or adding two tenths

 

[NDG Elecs]

Multiply by 1.25 is the quickest way.

 

[telectrix]

or divide by 0.8

 

[hightower]

Or times by the reciprocal of 0.8

 

[Zdb]

Divide by 0.8 is what I was doing but thanks to the table provided by @Richard Burns I don't need to anymore.

 

[pirate]

On the calculator on your phone, just enter the value and press +25%...
Oh isn't maths fun?
SO many ways to do your sums!

 

[pirate]

Unlike wiring a new bathroom extractor fan (without PIR)...ok, so many ways to do it...but only one correct answer.