This document addresses the mitigation and protection of telecommunications cabling from electromagnetic interference by describing: a) coupling mechanisms and possible countermeasures; b) assessment of the electromagnetic environment; c) filtering, isolation and surge protections measures. Safety (electrical safety and protection, optical power, fire, etc.) and electromagnetic compatibility (EMC) requirements are outside the scope of this document and are covered by standards and regulations. However, information given in this document can be of assistance in meeting these standards and regulations.