Table 7.4 - Maximum earth-fault loop impedance values for 240 V agricultural circuits to give a maximum 0.2 s disconnection time
Type of protection
Protection rating
Max. loop impedance
(A)
(ohms)
Cart. Fuse, BS 1361
5
9.60
15
3.00
20
1.55
30
1.00
Cart. Fuse BS 88 pt 2
6
7.74
10
4.71
16
2.53
20
1.60
25
1.33
32
0.92
MCB type 1
5
12.00
10
6.00
15
4.00
20
3.00
30
2.00
MCB type 2
5
6.86
10
3.43
15
2.29
20
1.71
30
1.14
MCB type 3
5
4.80
10
2.40
15
1.60
20
1.20
30
0.80

Extracted from The Electricians Guide Fifth Edition
by John Whitfield

Published by EPA Press
Click Here to order your Copy

Click here for list of abbreviations