Confined Conductive Locations with Restricted Movement

A specific, more stringent category of work environment under NEN 1010 §706 (based on IEC 60364-7-706), in which a person is largely surrounded by conductive surfaces (for example the inside of a metal boiler, tank, silo or pipe system) and, due to the limited physical space, can barely move or avoid contact with those conductive walls, causing the body contact area — and therefore the risk of a hazardous current through the body in the event of an electrical fault — to be considerably greater than in a normal work environment. Stricter requirements apply to these environments than to ordinary spaces: portable electrical tools and lighting may only be supplied via SELV with a maximum rated voltage of 25 V AC (or 60 V DC), via isolating transformers supplying only a single consumer, or via an RCD with a rated residual current of at most 30 mA combined with additional measures; the supply transformer or source itself must furthermore be located outside the confined conductive location. These requirements are similar to, but stricter than, those for wet locations, because the combined effect of complete surrounding by conductive material and the physical impossibility of getting away in the event of a fault substantially increases the risk.