This Recommendation describes working practices for service personnel to help service personnel work safely at telecommunication installations in three specific environments. The specific environments covered in this Recommendation are characterized by wet conditions or close proximity to exposed metallic parts. The working practices apply to telecommunications plant with voltage levels higher than the limits defined for analogue PSTN circuits, such as RFT-C or RFT-V circuits. This version of K.64 includes a warning regarding contact with terminals carrying RFT circuits with a small part of the body, e.g. back of the hand. The references have been updated.