7.13.13Maximum values of earth fault loop impedance#

AS/NZS 3000 Table 8.1 provides the maximum values of EFLI (Zs at 230 V) at 75°C. These values should be used when designing for cables that are carrying close to their rated current in standard conditions.

Table 7.13.13(a) – Maximum values of earth fault loop impedance at 75°C (AS/NZS 3000 Table 8.1)

Protective device rating (A)	Circuit-breakers Type B	Circuit-breakers Type C	Circuit-breakers Type D	Fuses	Fuses
6	9.58	5.11	3.07	11.50	15.33
10	5.75	3.07	1.84	6.39	9.20
16	3.59	1.92	1.15	3.07	5.00
20	2.88	1.53	0.92	2.09	3.59
25	2.30	1.23	0.74	1.64	2.71
32	1.80	0.96	0.58	1.28	2.19
40	1.44	0.77	0.46	0.96	1.64
50	1.15	0.61	0.37	0.72	1.28
63	0.91	0.49	0.29	0.55	0.94
80	0.72	0.38	0.23	0.38	0.68
100	0.58	0.31	0.18	0.27	0.48
125	0.46	0.25	0.15	0.21	0.43
160	0.36	0.19	0.12	0.16	0.30
200	0.29	0.15	0.09	0.13	0.23

Table 7.13.13(b) uses the data from Table 7.13.13(a) and modifies them in accordance with the resistance change with temperature parameters. These values should be used when testing EFLI with a typical conductor temperature of 25°C.

Table 7.13.13(b) – Test maximum values of earth fault loop impedance at 25°C

Protective device rating (A)	Circuit breakers Type B	Circuit breakers Type C	Circuit breakers Type D	Fuses	Fuses
6	8.03	4.28	2.57	9.64	12.85
10	4.82	2.57	1.54	5.36	7.71
16	3.01	1.61	0.96	2.57	4.19
20	2.41	1.28	0.77	1.75	3.01
25	1.93	1.03	0.62	1.38	2.27
32	1.51	0.80	0.49	1.07	1.84
40	1.21	0.65	0.39	0.80	1.38
50	0.96	0.51	0.31	0.60	1.07
63	0.76	0.41	0.24	0.46	0.79
80	0.60	0.32	0.19	0.32	0.57
100	0.49	0.26	0.15	0.23	0.40
125	0.39	0.21	0.13	0.18	0.36
160	0.30	0.16	0.10	0.13	0.25
200	0.24	0.13	0.08	0.11	0.19