At almost every meeting (conference, training session, etc.) devoted to machine safety where PIP — the Polish occupational safety inspectorate — is involved, there’s invariably a slide showing the relationship between minimum and essential requirements. The usual story goes like this: first there was chaos, then essential safety requirements were introduced for newly manufactured machines, and for older ones — built or imported earlier¹ — there came the so-called minimum requirements, a sort of “better than nothing” approach.

But if minimum requirements really apply only to old machines, meaning that the issue will eventually disappear as those machines are phased out — why does it keep coming up all the time?

Intellectualising the Matter

Strictly speaking, the so-called minimum requirements — or “minimum requirements for the safety and health of workers using work equipment” — are found in Annex I to Directive 2009/104/EC, also known as the Use of Work Equipment Directive (UWED).²

By contrast, the so-called essential requirements — or “essential health and safety requirements relating to the design and construction of machinery” — appear in Annex I to Directive 2006/42/EC, commonly known as the Machinery Directive (MD).

So, in the strict sense, Annex I to the MD applies only to machines manufactured after a country’s accession to the EU (May 2004 for Poland). All machines produced or imported into the EU in 2004 or later are subject to the requirements of Annex I to the MD.

However, in practice, both “minimum” and “essential” requirements are often used as shorthand for the entire directives that contain them. And UWED remains in force — not only for “old” machines. The key distinction is that UWED applies to users of machinery, while the MD applies to manufacturers. ³

Taking production (or import) dates into account, the overall picture looks like this:

Machines manufactured …	Manufacturers	Users
before 1 May 20044	no requirements5	UWED
1 May 2004 and later	MD	UWED + Annex I to MD

Simple enough, isn’t it?

But…

The essential requirements — Annex I to the MD — despite filling some thirty pages (in the Polish version), remain fairly general. Take, for instance, the clause on guards: they must be placed at an appropriate distance from the danger zone. But what distance counts as “appropriate”? Another provision on protective devices says they must be designed so that “persons cannot access moving parts.” How exactly can “access” be prevented if those devices don’t actually restrict operator movement? And then there’s the completely utopian demand that a machine be designed “in such a way as to prevent, or allow prevention of, all electrical hazards.”

Bureaucrats wrote these words, politicians approved them to sound reassuring — and now they have to be applied somehow, preferably without halting production.⁶
The proper interpretation of such requirements is established by standards harmonised with the MD. These standards are approved for use by the European Commission, but their content is developed by people who actually know what they’re talking about — so, surprisingly, the system works. For example, where the regulation says that all electrical hazards must be eliminated, the standard ⁷ clarifies that this can be achieved if the electrical cabinet meets IP2X protection — meaning that openings are no larger than 12.5 mm.

The minimum requirements, on the other hand, make no reference to harmonised standards, and there is no such thing as a standard harmonised with UWED. So how should we interpret requirements that are even more general than those of the MD? What does it mean, for instance, that “control systems must be safe and selected with due consideration of failures”? Or that machines “must be equipped with (…) devices that (…) prevent the movement of dangerous parts before a person reaches the danger zone”? How exactly do we determine the time needed to reach that zone?

The answer lies in Directive 89/391/EEC,⁸ which states that one of the general principles of prevention employers must apply is “adaptation to technical progress.”⁹
When looking for a benchmark of such technical progress in the field of machinery safety, there is hardly a more reliable source than the standards harmonised with the MD.

Take industrial robots, for example. Until 2006, standard EN 775:1992 required simply that a robot be fitted with an “enabling device.” Period. And indeed, older robots often had such a device — typically a button that, when released, stopped the robot during teaching. Today, standard ISO 10218-1:2012 specifies that the enabling device must have three positions, with only the middle one allowing movement; full depression triggers a stop, and restarting requires releasing and then pressing it back to the middle position. This is now considered an “obvious obviousness.”
But if an accident occurred on an old robot built before 2004 — where the operator, instead of releasing the button in a moment of danger, held it tight — would a court really find the machine adequately protected merely because the rules were different at the time of manufacture?

Back to Reality

Formally, the legal framework may appear convoluted: one directive for manufacturers, another for users, and parts of one applied in place of parts of the other, all topped off with national implementing acts. Yet, in the end, the assessment of machinery risk — whether carried out by the manufacturer or by the user — boils down to the same thing: verifying compliance with the standards harmonised with the Machinery Directive.

Image by David Bawm from Pixabay. Translated with Aria.