Earth fault loop impedance of cable

When an earth fault occurs at the far end of a cable it is possible that the armouring, cable gland and the frame of the consumer equipment can be raised to a dangerous potential with respect to
electric shock exposure to human operators. This subject has been given considerable attention over the last 20 years, and is well documented in for example IEC60364. The international  documentation concentrates on low voltage fixed and portable equipment protected by fuses and miniature circuit breakers.

source  : Handbook of Electrical Engineering: For Practitioners in the Oil, Gas and Petrochemical Industry. Alan L. Sheldrake  2003 John Wiley & Sons, Ltd ISBN: 0-471-49631-6