During installation, the air handling unit must be equipped with a device for safe disconnection from the electrical power supply. This device must enable disconnection of all electrical supply lines feeding the unit or its related parts, must be clearly identifiable, easily accessible to operating and service personnel, and must be marked as the main electrical switch of the unit.
The design of the main electrical switch depends on the selected delivery variant of the unit:
• For a unit with an external control cabinet supplied by the manufacturer, the main electrical switch is part of this control cabinet.
• For a unit with a control cabinet built into the unit, or for a unit supplied without a measurement and regulation system, or without a control cabinet, the main electrical switch is not included in the unit delivery. In such a case, the operator, or the professionally qualified installation company carrying out the electrical connection of the unit, is responsible for the design, installation, location, accessibility and marking of the main electrical switch.
The electrical connection of the unit, installation of the main electrical switch, its marking and verification of its correct function may only be carried out by a person with the appropriate electrical qualification, in accordance with the applicable legal regulations, project documentation and technical specification of the specific unit.
Before starting any work on the unit, especially before service intervention, cleaning, maintenance, inspection of electrical equipment or intervention in moving parts, the unit must be safely disconnected from the electrical power supply using the main electrical switch. If unintentional or unauthorised switching on could occur, the disconnecting device must be secured against switching on again.
Procedure for switching off the unit using the service switch during service and operating activities
Before starting service, maintenance, cleaning or operating activities during which contact with electrical equipment, moving parts of the unit or other dangerous parts may occur, the unit must be safely taken out of operation and disconnected from the electrical power supply.
Recommended procedure:
• Switch off the unit in the standard operating manner via the control system or control panel, if the unit is equipped with such a system.
• Wait until the fans, rotary regenerators, dampers and other moving parts have come to a complete stop.
• Switch off the service switch of the relevant part of the unit, or the main electrical switch of the unit if no service switch is installed.
• Secure the switched-off service switch or main electrical switch against unintentional or unauthorised switching on again, for example by locking it in the off position or by using another suitable securing device.
• Verify that the unit is not in operation and that no parts of the unit are moving.
• Service, maintenance, cleaning or operating activities may only be started after the above steps have been completed.
After completion of the work and before putting the unit back into operation, it must be checked that all service doors and covers are closed, that the safety devices are functional, that no persons, tools or foreign objects remain inside the unit, and that the unit is in a condition enabling safe operation.