“Safety requirements concerning the lighting of machinery”
1. General requirements
Requirements concerning the integral lighting of machinery are set out in Appendix 1 to the Machinery Directive, p. 1.1.4 — “Lighting”. According to these requirements:
- Machinery must be supplied with integral lighting suitable for the operations concerned, where the absence thereof is likely to cause a risk despite ambient lighting of normal intensity.
- Machinery must be designed and constructed so that there is no area of shadow likely to cause nuisance, that there is no irritating glare and that there are no dangerous stroboscopic effects on moving parts due to the lighting.
- Internal parts requiring frequent inspections and adjustments as well as maintenance areas must be equipped with the relevant lighting.
Requirements concerning electrical lighting for the purposes of supplementing ambient lighting are set out in detail in the following standards:
- EN 1837+A1:2009 Safety of machinery. Integral lighting of machines.
- EN 12464-1 2011 Light and lighting. Lighting of work places. Part 1: Indoor work places.
Ergonomics and lighting techniques need to be taken into account when designing machinery lighting. Visual tasks which are to be performed on a machine vary when it comes to their sizes, contrast, position, speed of movement, etc. In order to provide optimum lighting conditions, detailed analysis of a given visual task needs to be conducted in the first place.
2. Intensity of lighting
The required lighting intensity depends on the type of visual task, and must be sufficiently high and uniform in order to allow for safe and comfortable perception of visual task details. In general, lighting intensity at the level of at least 500 lx must be ensured, with the minimum uniformity of Uo = 0.7 within the task area, and 0.4 within the immediately surrounding area.
In places where a shield or a protective screen is required to be used with a machine, lighting intensity needs to be multiplied by the reciprocal value of light transmittance factor for the additional equipment. In cases where the light transmittance factor is not known, lighting intensity shall be increased at least by 50%. In situations where light negatively impacts technological processes, levels of lighting intensity can be reduced.
3. Glare
Integral lighting system shall not cause direct glare, both for the operator of a machine and for other employees working in adjacent work places. Reflective glare must be minimised as much as possible.
Glare limitation is possible due to the relevant arrangement and orientation of luminaires, the application of correct shielding mounted at luminaires, and illuminated surfaces being given a matt finish.
4. Orientation of lighting
Integral lighting system shall be designed and orientated in such a way so that there is no area of shadow likely to cause nuisance within the area of visual task. The orientation of lighting shall ensure correct perception of a form for a given visual task.
5. Colour of lighting
Colour rendering characteristics of installed light sources in luminaires shall allow for correct differentiation of colours within a given visual task and fulfill requirements for specific activities set out in the EN 12464-1 2011 standard. Light and lighting. Lighting of work places. Part 1: Indoor work places.
Colour of light emitted by installed light sources in luminaires shall be selected in a manner ensuring that works can be performed in visual comfort. In most cases, warm to neutral colours are preferred. (2700 K, 3000 K up to 4000 K).
6. Stroboscopic effect
Integral lighting system shall be designed in such a way that stroboscopic effects which may lead to dangerous situations due to alternating perception of movement, rotation or reciprocating motion (of a piston for instance) of machinery are eliminated. This may be achieved, for instance, by the use of light bulbs, direct current for the supply of luminaires, or powering gas-discharge lamps using high-frequency current (approx. 30 kHz) with electronic ignition systems.
7. Light sources
Only light sources that ensure operational safety and the safety of machine operators can be used. It is recommended that light sources are shielded in order to protect operators against injury, e.g. in the case of a lamp bursting, excessive heat, or the emission of UV radiation. Standard glass can act as a shield and UV radiation filter. As far as halogen light bulbs are concerned, they shall be marked with the following inscription: UV STOP or Low Pressure. This means that their manufacturer has ensured the limitation of UV radiation.
8. Luminaires
They shall be designed so as to:
a/ ensure sufficient illumination of the area of visual task,
b/ limit the accumulation of dust and dirt on light sources and optical surfaces,
c/ limit premature ageing of optical elements,
d/ ensure comfortable operation,
e/ be compliant with the EN 60598 standard,
f/ be compatible with particular machines, e.g. resistant to vibration, radiation, marked with appropriate IP code, etc.
9. Mounting
Luminaires shall be mounted so as to:
a/ ensure the required level of illumination for visual tasks,
b/ avoid colliding with visual tasks or posing threats to the operator,
c/ limit the accumulation of dirt on light sources and luminaires,
d/ ensure easy and comfortable operation.
10. Availability of lighting
Where risks may increase as a result of failure of the integral lighting system of machinery, the lighting system shall consist of at least two light sources. One of the light sources shall be equipped with a separate power supply.
11. Power supply
Lighting system shall be connected to a power supply source so that it can function even when the machinery is powered off.