Guidance Note 5: Protection Against Electric Shock provides a core element of safety for specifiers, designers, contractors and inspectors. It includes clear guidance on how to apply the safety requirements of BS 7671 concerning electric shock and has been fully updated to BS 7671:2018+A4:2026, including Power over Ethernet; maximum permissible measured earth fault loop impedance (EFLI), guidance on the verification of site applied insulation.