Standards / Machinery Safety

Safety Distances and Reach

EN ISO 13857 is the European standard that establishes the safety distances preventing hazard zones being reached by the upper and lower limbs. It is the source of the tables that relate the size of an opening to how far the hazard must sit behind it, and of the distances for reaching over, under and around a barrier.

Scope

EN ISO 13857 applies to the protection of people over a stated age by means of distance, covering reaching upwards, reaching over a protective structure, reaching around an edge, and reaching through regular and irregular openings with the upper limbs, together with distances for the lower limbs.

Exclusions & Related Standards

• The design and construction of the guard providing the distance falls under EN ISO 14120.
• The positioning of presence-sensing devices, which depends on approach speed and stopping time rather than reach alone, falls under EN ISO 13855.
• Gaps intended to avoid crushing a specific body part are a separate consideration from preventing reach.
• The overall risk assessment framework is ISO 12100.

Key Requirements & Marking

The distances are based on measured human reach and are stated as pairs: for a given opening size, a minimum distance from the opening to the hazard. Larger openings admit more of the limb and therefore require greater distance. Separate tables address reaching over a protective structure, where the height of the structure and the height of the hazard together determine the horizontal distance required.

Opening size and distance to the hazard are a single decision, not two independent ones.

Testing Overview

The standard is applied by measurement and calculation rather than by test: the opening dimensions, the barrier height and the position of the hazard are measured and compared against the tabulated distances, taking account of the positions from which a person can actually approach.

Selection Guide

Apply the tables to every route by which the hazard could be reached, not only the obvious one: through the opening, over the top, under the bottom edge and around the side. Consider the standing surfaces available, since a step, platform or stacked material changes the reach that was designed for, and reassess whenever the area around a machine is rearranged.

Inspection, Care and Maintenance

• Reassess safety distances whenever the layout around a machine changes, including new platforms, steps or stored material
• Check the gap beneath guards and enclosures, which is the reach route most often overlooked
• Confirm guards extend far enough at the sides that the hazard cannot be reached around the end
• Recheck after any modification that moves a hazard closer to an opening
• Do not increase an opening size for visibility without recalculating the distance required

The gap under the guard is the route most often assessed last, or not at all.