The standard EN ISO 13857 is crucial for determining minimum safety distances that prevent limbs (both upper and lower) from reaching hazardous areas of machinery. This standard forms the foundation of machine design, ensuring minimized risk of accidents. It is also harmonized with the requirements of the Machinery Directive, allowing for a presumption of conformity with machine safety legislation.
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Principles of EN ISO 13857
The primary aim of PN-EN ISO 13857 is to establish minimum dimensions and distances so that a worker’s hand or foot cannot reach a danger zone. These values consider typical anthropometric measurements and limb biomechanics.
The standard identifies two main risk categories:
- Low risk (where the hazard is minor and potential injuries are not severe),
- High risk (where there is a high likelihood of an accident with severe consequences).
Depending on the risk classification, PN-EN ISO 13857 allows for different minimum distance values. A risk assessment should always be conducted first, followed by the application of appropriate values for the specific situation.
Reaching Without Protective Structures
One method to eliminate hazards is to place dangerous elements at such a height or distance that they are practically unreachable. For upper limbs, the minimum height is often set at 2.5 meters (for low risk) or 2.7 meters (for high risk). This means that if rotating machine parts are positioned above these heights, additional barriers are not necessary.
In practice, relying solely on distance is rare. A change in work position or using an object (like a chair) to reach a dangerous point can suffice. Consequently, protective structures such as guards or enclosures are commonly used.
Reaching With Protective Structures
PN-EN ISO 13857 details the relationships between:
- the height of the danger zone,
- the height of the protective structure (guard, fence),
- the minimum horizontal safety distance from this zone.
The principle is simple: the lower the barrier, the greater the distance from it to the danger zone. Similarly, the further the protective structure is from the machine, the lower it can be. In practice, guards with a height of at least 1400 mm are commonly used, as these dimensions are deemed sufficient for effective protection, even at higher risk levels.
For situations with low risk, slightly lower guards (e.g., 1000 mm) are acceptable. However, they must be appropriately distanced from the danger zone, often over 1 meter.
Size of Openings in Guards
A specific area of application for PN-EN ISO 13857 is selecting the size of mesh openings in guards. The general rule is: the larger the opening, the greater the safety distance from this opening to the danger zone should be.
The standard distinguishes several categories of opening sizes and shapes (round, square, slotted). For example:
- Openings up to 4 mm – require minimal clearance (a few millimeters),
- Openings from 12 to 20 mm – require about 120 mm of clearance,
- Openings 30–40 mm (especially slotted) may require up to 850 mm of distance if they allow the insertion of an entire forearm.
Therefore, in production practice, meshes with a 20 mm opening are often used to minimize the necessary distance from the machine. If larger openings (e.g., 50 mm × 50 mm) were used, the space around the danger zone would need to be significantly increased.
Fencing for Robotic Cells — Practical Tips
For robotic cells, mesh panel guards are frequently used to restrict access to the robot. When choosing mesh fencing, consider:
- Mesh size: According to EN ISO 13857, mesh sizes in the 20–30 mm range may require large distances in some configurations. It is advisable to choose meshes below 20 mm.
- Fence height: A minimum height of 1400 mm is standard. For higher risk or if the robot cannot be distanced, panels of 2000 mm or even 2200 mm height can be used.
- Minimum distance from hazardous elements: If there is a risk of reaching through the mesh, check the standard tables for the required protective zone width between the mesh and the robot or other potentially hazardous elements.
- Ground clearance and gap at the bottom: The standard also specifies the maximum gap to prevent feet or legs from sliding under the fence. Commonly, a maximum gap of 100–180 mm is used.
- Doors and locks: Every entry to the robotic cell must be equipped with a system controlling its opening (e.g., safety sensor) and possibly a safety lock with a properly defined safety function.
Following these guidelines helps ensure safe working conditions at robotic workstations and meet the requirements of PN-EN ISO 13857 and the Machinery Directive (or the “new Directive,” Regulation on Machinery 2023/1230/EU).
The EN ISO 13857 standard clearly defines how to design protective distances and select the sizes and shapes of openings in protective structures to prevent reaching dangerous areas. In practice, this means:
- A danger zone can remain unguarded only if it is positioned high or far enough that reaching it is impossible.
- If guards are necessary, their height and distance from the hazard are selected according to the tables in the standard, depending on the risk level.
- The larger the opening (in mesh or slot), the further the danger zone must be moved away.
- For robotic cells or production lines, special attention is paid to selecting mesh panels with openings that allow maximum proximity of the fence to the robot while maintaining required safety.
Adhering to the recommendations of PN-EN ISO 13857 not only eliminates or significantly reduces the risk of accidents but also ensures compliance with key requirements of the Machinery Directive. This makes working with machines much safer and more ergonomic.
FAQ: EN ISO 13857 and Minimum Safety Distances
No. The standard describes the principles of determining safe distances in general, regardless of the type of protective structure. These can be sheet metal guards, tubular barriers, or mesh panels — the important thing is that they guarantee the required distances.
The key factor is risk assessment. If a potential injury is minor and infrequent, values for low risk are applied. In cases of high severity and frequency (high risk), stricter requirements must be chosen.
Yes. EN ISO 13857 is based on anthropometric data, considering average limb dimensions for a large part of the population. This ensures that a typical user cannot reach beyond a given guard.
Theoretically yes, if the limb’s reach is insufficient to reach the danger zone. In practice, however, additional fences or guards are often used because distancing alone is not always enough (e.g., there is a possibility of using a ladder or another means to reach).
It’s a good foundation, but other standards are often needed — such as those covering robot safety, two-hand control, or limit switches on doors. EN ISO 13857 defines dimensional aspects of protection against reaching, but full protection is guaranteed only by the combined use of various safety solutions.