Adiabatic Equation

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Please can some one explain how to use adiabatic equation to work out main earth
BS1361 Main Fuse 100A
PFFC 1300A
Meter Tails 10mm
 
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Using the equation S=root(I²t) / K
Assuming you mean PEFC as in prospective earth fault current?

For a copper earthing conductor, table 54.2, K=143
At 1300A, a BS 1361 will disconnect in approx 0.3s
So for a protective conductor the minimum size required is calculated by root (1300² x 0.3) / 143 = 4.97mm

For the meter tails - 10mm isn't suitable for a 100A supply, need to be 25mm so may effect your PEFC when they are replaced!
Better to stick to table 54.7 imho.
 
What bout 50A bs60898 type c breaker 10mm tails pfec 1300? cant work dis time from chart
 
Use 0.1s for the MCB, or consult the manuacturer for the I²t energy let through value.
 
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Use t of 0.1s, if you want a more accurate time then you'll need to reference manufacturers data.

EDIT - beaten to the punch (like Chuck Liddell on Sunday morning if you watch UFC!)
 

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