Zs values?

[Spinksy]

Yeah it was but has not happened before ! and the meter is fairly new it must be reading the Rcd !

 

[tomxhug]

I want to find a table or something so I can see the Ka ratings as per different device type.Or at least someone to explain it in simpleton terms

on site guide and GN3 have tables with the standard kA ratings of all protective devices manufactures will give more details

 

[telectrix]

0.06 seems low to me for Ze. if i am doing Zs on no trip, i usually do the Ze on no trip . no doubt someone will correct me on this, but i do it this way so as to make the readings same parameters as regards the test equipment.

 

[jam2020]

why are osg tables 80% of bs7671?

 

[J@mes]

to allow for changing temperature conditions I think!

 

[JUD]

why are osg tables 80% of bs7671?

When you do the Zs test the cable temperature will be around 20°C. The tables in the regs are the max Zs values when the cable temperature is 70°C.

As resistance increases as cables get hotter (0.4% per °C) you need to adjust the max Zs value for the lower temperature of the cable.

e.g The difference between 20°C and 70°C is 50 so the calculation would be 50 x 0.4% = 20% so the corrected max Zs values for 20°C would be 20% less than the ones for 70°C.

Hope that makes sense

 

[jam2020]

on the eic you would still enter the max zs allowed though?

 

[JUD]

on the eic you would still enter the max zs allowed though?

correct

 

[malcolmsanford]

on the eic you would still enter the max zs allowed though?

Unless the circuit is RCD protected then you would use 1667 for either TT or TN

 

[telectrix]

malcolm, could you clarify your last post please. say for a 32AMCB, the max. allowable value of Zs is 1.16, what you are saying is, if the circuit is RCD protected you enter 1667, not 1.16?