Max Zs on certification

[Dan007]

Please can people clarify what value they insert in the Max Zs field on certification.

I've always input 100%. Currently in disagreement with another person as they are specifying 80%.

Done my 2391 in 2008 and I was taught and told it's always 100% and it's down to the QS to interpret the results and ensure they fall with 80% allowing for correction factors.

Third argument is that in GN3 and OSG they specifically state 80% - however I always understood these to be quick reference pocket guides while on site.

In the mentioned publications and BBB the model forms show 100% in the compelte fields for examples. Secondly the small print at the bottom makes reference to the Publication and values in Chapter 41 aka BBB and 100% values.

Your thoughts please people

 

[Deleted account]

You missed out Cmin factor.

 

[Generator]

Quite right Pete - forgetting about Am't 3! - U0 x 0.95. So the rule of thumb ought to be 76% then? I'm on 240, nearly 250 - so that drops my dis time from 0.4 to 0.2 secs ( no difference for a Type B tho ).
They probably class my Uo as 230! It messed my PV inverter about tho, till I upped a few settings.

 

[PatH]

Please can people clarify what value they insert in the Max Zs field on certification.

I've always input 100%. Currently in disagreement with another person as they are specifying 80%.

Done my 2391 in 2008 and I was taught and told it's always 100% and it's down to the QS to interpret the results and ensure they fall with 80% allowing for correction factors.

Third argument is that in GN3 and OSG they specifically state 80% - however I always understood these to be quick reference pocket guides while on site.

In the mentioned publications and BBB the model forms show 100% in the compelte fields for examples. Secondly the small print at the bottom makes reference to the Publication and values in Chapter 41 aka BBB and 100% values.

Your thoughts please people

I have found so many inconsistencies and mistakes in the on site guide that it can't be relied on. Take a look at the test and inspection sheets in the appendix section. Some of the values inserted are incorrect and the advice notes don't match the forms. I would always suggest that you use your experience and knowledge in any conundrum. In this case I would enter the 80% value as this is the worst case scenario in any instance