Table 7.4
Values of Loop Impedance for Comparison with Test Readings.
Protection
Disconnection Time
BS 3036 fuse
0.4 s
Zs
5A
6A
10 A 15 A 16 A 20 A 25 A 30 A 32 A
40 A 45 A
50 A 60 A 63 A 80 A 100 A 125 A 160 A
7.6
–
–
2.04
–
1.41 –
0.87 –
–
–
–
–
–
–
–
–
–
14.16 –
–
4.2
–
3.06 –
2.11 –
–
1.27
–
0.89 –
–
0.42
–
–
2.16
1.42 1.15
–
0.83
–
–
–
–
–
–
–
–
–
1.47
1.08
–
0.83 –
0.67
0.45
0.33
0.26
0.2
–
–
–
–
–
max 5s
Zs max
BS 88 fuse
0.4 s
Zs
–
6.82 4.09 –
max 5s
Zs
–
10.8
5.94 –
3.33
2.32 1.84
–
8.36
–
–
2.62
–
1.36 –
0.92 –
–
–
–
–
13.12 –
–
4
–
2.24 –
1.47 –
–
0.79
–
0.56 –
0.4
0.29
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
max BS 1361 fuse
0.4 s
Zs max
5s
Zs max
BS 1362
0.4 s
Zs
(3 A)
(13 A) –
max 13.12
fuses 5s
Zs
1.9
(3 A)
(13 A) –
max 18.56 BS 3871 MCB 0.4 & 5 s
Zs
Type 1
max
BS 3871 MCB 0.4 & 5 s
Zs
Type 2
max
BS 3871 MCB 0.4 & 5 s
Zs
Type 3
max
BS EN 60898
0.4 & 5 s 0.4 & 5 s
CB Type D
7.6
3.06
2.87
2.3
1.84
1.53 1.44
1.15
1.02
0.92 –
0.73
–
–
–
–
5.25
4.37 2.62 1.75
1.64
1.31 1.05
0.87 0.82
0.67
0.58
0.52 –
0.42
–
–
–
–
1.15
0.92 0.74
0.61 0.57
0.46
0.41
0.37 –
0.29
–
–
–
–
6.13 3.68 –
2.3
1.84 1.47
–
1.15
0.92
0.74 –
0.58
0.46
0.37
0.3
–
3.06 1.84
1.15
0.92 0.75
–
0.57
0.46
0.37 –
0.288 0.23
0.18
0.15
–
1.54 0.92
0.57
0.46 0.37
–
0.288 0.23
0.18 –
0.14
0.09
0.07
–
3.68 (3 A)
3
4.6
1.84 1.22
Zs max
CB Type C BS EN 60898
9.2
max 12.26
CB Type B BS EN 60898
Zs
3.06
0.4 & 5 s
Zs max
0.12