Crane & Lifting Equipment Electrical Safety Requirements
Disconnect Switches and Contact Protection
Components must be marked with a label indicating they are protected against unintentional direct contact with live parts. If circuit disconnect switches pass through rings or busbars, they must be protected against direct contact with a minimum degree of protection of IP2X. Maintenance disconnects may be omitted if the emergency switches specified in section 4.2 are connected to the installation’s input supply. For a single crane installation, the main power switch for the crane can fulfill the function of the disconnect switch.
Emergency Cut-off and Stop
Each crane, lifting device, or transport system must have one or more emergency stop mechanisms accessible from all operating positions.
Emergency stop mechanisms must ensure that a single action causes the appropriate power supply cut-off. Key requirements include:
- Emergency devices must act as directly as possible on the appropriate power supply conductors.
- Reconnection of the supply after an emergency cut-off must be prevented by electrical or mechanical interlocks.
- Reconnection should only be possible from the control device where the emergency stop was initiated.
Each crane must have an emergency stop device operable from the ground/floor level. Where permitted, the emergency cut-off can be achieved by operating a load-breaking switch at the installation’s supply point, provided it is easily accessible.
Cranes and lifting equipment controlled from the ground must stop automatically when the operating control mechanism is disconnected.
Switchgear
Switches (General)
Switches must comply with BS EN 60947-2 and be installed in positions that allow functional tests to be carried out safely. Contactors meeting relevant standards are also permitted, but contactors must not be used for isolation (sectioning) purposes.
Supply-Side Isolation Switches
It must be possible to isolate collector rings, rods, or cables from the main supply before the crane’s connection point using supply-side switches for repairs and maintenance. Connectors and sockets conforming to BS EN 60309-1 can be used for this purpose.
Specific requirements for supply-side switches include:
- When a slip ring or busbar is fed by multiple parallel switches, they must be interlocked to disconnect all supplies simultaneously, even if only one switch is operated.
- It should only be possible to operate a switch controlling an accessible slip ring or busbar from a location where that slip ring or busbar is clearly visible.
- Supply-side switches or their control mechanisms must be guarded against untimely or unauthorized closure (e.g., lockable).
For cranes and lifting equipment on construction sites, the machine’s main switch can serve as the installation’s supply-side switch. The requirement for safeguarding against unauthorized closure is met if other measures (like key locks or padlocks) prevent the device’s commissioning.
Earthing and Protective Conductors
When power is supplied via collector cables, busbars, or slip ring assemblies, the protective conductor (PE) requires specific provisions:
- The protective conductor must utilize a dedicated busbar or slip ring.
- Supports for the protective conductor must be clearly visible and distinguishable from those supporting active (live) conductors.
- In environments with corrosive gases, high humidity, or excessive dust, special protective measures are necessary for collector rings, bars, or rails used as protective conductors.
- Protective conductors must not carry current during normal operation.
- Protective conductors must be installed sliding on insulating supports.
- Lifting appliances must be securely connected to the protective conductors; using wheels or rollers for this connection is not permitted.
- Collectors designated for protective conductors must not be interchangeable with collectors used for other conductors.