Context card
Documenting foreseeable misuse without making it an option
How do instructions describe reasonably foreseeable misuse without presenting it as a way to use the product?
The short answer
By stating it as a boundary, not as a variant of use. Reasonably foreseeable misuse is identified in the risk assessment; the instructions name what must not be done, say why, and keep it apart from the descriptions of intended use and from procedures. A prohibited action written like an operating step, or explained in so much detail that it reads like a workaround, normalizes the very behaviour it is meant to prevent.
For: Technical writers and product safety engineers writing safety information and instructions for use of machinery
Key points
- ISO 12100 defines reasonably foreseeable misuse as use not intended by the designer that can result from readily predictable human behaviour.
- It is identified in the risk assessment; the writer documents its result and does not decide alone what counts as misuse.
- EU machinery law requires the instructions to warn against ways the machinery must not be used that experience has shown might occur.
- A prohibition names the action, the consequence and, where it helps, the intended alternative — not a step-by-step description of the misuse.
- Misuse is placed with the intended use in the safety information and, where it is likely during a task, as a warning before that task.
The context
What it is
Reasonably foreseeable misuse is the use of a machine in a way not intended by the designer, but which can result from readily predictable human behaviour (ISO 12100). It is the counterpart of intended use, and both are defined in the risk assessment: the manufacturer identifies the misuse, reduces the risk by design and protective measures where possible, and addresses what remains in the information for use.
The Machinery Regulation (EU) 2023/1230, which applies from January 20, 2027 (until then the Machinery Directive 2006/42/EC), asks in Annex III, section 1.7.4.2, for the instructions to describe the intended use and to warn against ways in which the machinery must not be used that experience has shown might occur.
A boundary, not an option
The risk in documenting misuse is that the documentation itself makes it look normal:
- A prohibited action written as a numbered step reads like an instruction.
- A detailed explanation of how a guard could be bypassed is a manual for bypassing it.
- A misuse listed between operating options looks like one of them.
A prohibition works when it is short and unmistakable: what must not be done, what happens if it is done, and — where it helps — what to do instead.
| Instead of | Write |
|---|---|
| “To clear a jam quickly, the guard can be opened while the conveyor runs.” | “Never open the guard while the conveyor is running. Moving parts can trap hands. Stop the conveyor and wait until it has come to a standstill before clearing a jam.” |
Where it goes
The prohibitions that apply to all use stand with the intended use in the safety information. A misuse that is likely during a specific task — under time pressure, during cleaning, during fault recovery — is also warned about directly before that task, as a warning message.
This card is related to risk thinking in the blueprint Thinking models for technical writers. Documenting misuse does not make a machine safe or compliant; the content follows the manufacturer’s risk assessment.
Questions readers ask next
- Is every possible misuse listed in the instructions?
- No. The instructions address the misuse that the risk assessment identifies as reasonably foreseeable and that is not eliminated by design or protective measures. An endless list of improbable misuses would bury the relevant ones.
- Should the instructions explain why something is prohibited?
- Yes, briefly. Naming the consequence helps readers accept a prohibition; a long technical explanation of the misuse itself should be avoided.
- Who decides what counts as foreseeable misuse?
- The manufacturer, in the risk assessment. The technical writer can contribute experience from service and users, but does not decide alone.
Sources
- ISO 12100:2010 Safety of machinery — General principles for design — Risk assessment and risk reduction — ISO, 1 November 2010
- Regulation (EU) 2023/1230 on machinery — Official Journal of the European Union, 29 June 2023
- IEC/IEEE 82079-1:2019 Preparation of information for use (instructions for use) of products — Part 1: Principles and general requirements — IEC, 8 May 2019
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