Crabtree C50 max zs

[mwigham85]

I recently asked what the max zs would be for a Crabtree C50 7.5a breaker and didn't find the answer but if any one else ever needs to know here's a formula take the breaker rating 5,7.5,10 etc multiply by ( 4 for type1) (7 for type 2) and (10 for type 3) then divide 230v by that value once you have your max permitted zs multiply it by 80% so for a Crabtree C50 type 2 7.5a you would do 230v divided by (7.5x7) x 0.8 which equals 3.50 zs

 

[ashrow]

Interesting and thank you

 

[Mark.W]

Type B (5 x In) / 230
Type C (10 x In) / 230
Type D (20 x In) / 230

 

[silverfox1]

Thanks for info gents .

 

[Briggs12345]

Out of interest where did you get this info?

 

[newfutile]

This is the old way of doing it , now we also use cmin so If you multiply your answer by 0.95 it gives about 3.33 ohms