IEC 60204-32 — hoisting machines: why a crane's electrical safety needs more than 60204-1

The guide on NEN-EN-IEC 60204-1 covers the general standard for the electrical equipment of machines, and where NEN 1010 stops and 60204-1 begins. A hoisting machine — an overhead travelling crane, a hoist, a goods lift used as lifting equipment, a mobile crane's electrical control system — needs more than that general standard alone: IEC 60204-32 ("Requirements for hoisting machines") applies on top of 60204-1, adding requirements that follow from one specific hazard ordinary machinery does not have: a suspended load that must not be allowed to fall, drift, or descend uncontrolled when something in the electrical system goes wrong.

Why a suspended load changes the safety logic

For most machinery, the default safe reaction to a fault or an emergency stop is simple: remove power, and the machine stops moving. For a hoisting machine that default is not automatically safe — if a loaded hook is held up purely by an energised motor with no mechanical brake engaged, removing power without first setting the brake lets the load fall under gravity. IEC 60204-32 therefore does not simply layer generic emergency-stop requirements onto a crane; it specifically addresses how power removal and braking must be sequenced and supervised so that a suspended load is held, not dropped, whenever power is interrupted — whether that interruption is intentional (emergency stop) or a fault (loss of supply, a blown fuse, a failed contactor).

Brake control circuits: supervised, not just powered

A hoisting machine's mechanical brake (almost always a spring-applied, electrically-released brake — spring-applied so that the absence of power is the fail-safe state that clamps the brake) must be controlled through a circuit that IEC 60204-32 requires to be supervised, not merely switched:

The brake-release command and the motor-run command are interlocked, so the brake cannot be released while the motor is not actually driving, and the motor is not driven while the brake is still mechanically applied.
A failure in the brake circuit itself (a contact welded closed, a broken monitoring contact) must be detectable, rather than silently leaving the brake permanently released.
Where more than one brake is fitted on a single hoisting motion (for example a service brake plus a separate emergency/safety brake), each brake circuit is treated and supervised largely independently, so that a single failure does not remove all braking at once.

Overtravel and slack-rope/slack-chain protection

IEC 60204-32 requires limiting devices specific to hoisting motion that 60204-1 does not itself define:

Overtravel limit switches stop the hoist motion before the load block reaches the end of its travel (top or bottom) in a way that could cause mechanical damage or a two-blocking condition (the hook block being pulled into the drum/sheave assembly).
Slack-rope/slack-chain detection stops the hoist when the rope or chain goes slack — for example when a load has landed on an obstacle while still being lowered — preventing the rope or chain from continuing to unspool and then re-tensioning suddenly with a shock load, which can damage the rope or chain or cause it to jump off its sheave.

Emergency stop: stopping the motion, not dropping the load

A normal Category 0 emergency stop (immediate removal of power, per the emergency-stop categories guide) is not automatically the correct behaviour on a hoisting motion: simply cutting power to the motor without controlling the brake sequence would let a suspended load fall. For the hoisting motion specifically, IEC 60204-32 requires the emergency-stop function to bring the load to a stop and then hold it there — in practice usually by setting the mechanical brake as part of the stop sequence rather than relying on the motor alone, and specifically avoiding an emergency-stop design that behaves as an uncontrolled Category 0 stop on the hoist motor while the brake circuit is not simultaneously commanded closed.

Motor thermal protection: warn first, do not just trip

An ordinary machine's motor overload protection can simply disconnect the motor when it overheats — the process stops, and that is an acceptable outcome. For a hoisting motion with a load suspended in the air, an unannounced overload trip that removes power without first setting the brake has the same dangerous consequence as an uncontrolled emergency stop. IEC 60204-32 accordingly expects thermal protection arrangements for hoist motors that avoid this — for example a pre-warning stage before the final trip, or an arrangement where an overload trip is coordinated with the brake circuit so the brake is confirmed set before the motor is actually de-energised.

Note: this article covers the principles that distinguish IEC 60204-32 from the general 60204-1 requirements. The exact circuit topology (how many independent brakes, how overtravel and slack-rope devices are wired into the safety circuit, and how thermal protection is coordinated with the brake) is design- and manufacturer-specific; for a concrete installation the full standard and the crane manufacturer's documentation are decisive.

Practical relevance

When inspecting or commissioning an overhead crane, hoist, or lifting platform under NEN 3140, it should be verified — beyond the general 60204-1 checks already covered for ordinary machinery — that: (1) the brake circuit is actually supervised, not just switched, (2) overtravel and slack-rope/slack-chain protection are present and functional, (3) the emergency stop on the hoisting motion actually results in the load being held, not free-falling, and (4) motor thermal protection does not remove power from a loaded hoist motor without the brake first being confirmed set.

Common mistakes

Applying only the general IEC 60204-1 checklist to a crane or hoist, without the additional IEC 60204-32 checks that follow specifically from the suspended-load hazard.
Treating a Category 0 emergency stop on a hoisting motion the same as on an ordinary machine — an uncontrolled removal of power without a coordinated brake sequence can let a suspended load fall.
Assuming the brake circuit is safe simply because a brake is fitted — without supervision of that circuit, a single fault (a welded contact, a broken monitoring wire) can leave the brake permanently released without anyone noticing.
Not verifying overtravel and slack-rope/slack-chain protection during a periodic inspection, treating them as a one-off commissioning check rather than a function that can itself fail over time (a worn limit switch, a misaligned slack-rope sensor).