Max Earth Fault Loop Impedance for OverCurrent Devices Before Amendment 3 and Now???

[Mark Wright]

Maximum Earth Fault Loop Impedance for OverCurrent Device was calculated
230/(MCB Rating*5) * Rule of Thumb
is that correct?

And how are they worked out now after Amendment 3?

 

[telectrix]

same as before but with a 5% reduction to allow for dupply voltage low limit of about 216V. think it's called a Ci factor.

 

[Mark Wright]

Thanks ill try it but I just read on another forum
"The IET don't actually calculate it - it derives from the circuit breaker product standard."

------.org/forums/forum/messageview.cfm?catid=205&threadid=39081

don't know if it's garbage?
[automerge]1583529462[/automerge]
Sorry it works perfectly, Thanks again.

 

[telectrix]

Thanks ill try it but I just read on another forum
"The IET don't actually calculate it - it derives from the circuit breaker product standard."

------.org/forums/forum/messageview.cfm?catid=205&threadid=39081

don't know if it's garbage?
[automerge]1583529462[/automerge]
Sorry it works perfectly, Thanks again.

WTF is That???

 

[Mark Wright]

Yeah I found something on another forum and posted but after trying your suggestion and it worked I crossed out what I'd written before, Thanks.

 

[telectrix]

thought i was going cross eyed and almost binned my Scotch.