Fuses may be used for protection against electric shock by indirect contact - i.e., faults to exposed metalwork of the installation. The HRC fuse characteristic will determine the permissible earth loop impedance figure and relevant figures for certain sizes of BS 88 fuse, taken from the 16th Edition of the IEE Wiring Regulations Table 41D is reproduced below. The figures are derived from the BS 88 time/current zones to achieve disconnection within 5 seconds for fixed equipment circuits. The published figures are relevant to 240 volt-to-earth systems and should br multiplied by the ratio Uo/240 for any alternative voltage-to-earth (Uo).

Table 41D
Maximum earth fault loop impedance (Zs) for 5s disconnection time with Uo240V (see Regulations 413-02-13 and 413-02-14)