Limits of Approach (Vicinity/Contact Zone)

The defined safety distances around live parts that determine which precautions and authorisations (SP/instructed person/layperson) are required as someone approaches: outside the limit of approach, no special measure is needed; between the limit of approach and the limit of contact, only a Skilled Person or specifically authorised instructed person may enter (with additional measures where required); and within the limit of contact, work on live parts is permitted only by a specifically authorised and trained Skilled Person, with the corresponding PPE and work procedure. The exact distances depend on the voltage level and are given per voltage class in NEN 3140. This concept is distinct from the arc-flash boundary, which specifically describes the incident-energy threshold for thermal injury from an arc flash.