| 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.