WARNING   Risk of electric shock through contact with live wires   An electric shock can be life-threatening or lead to serious injuries such as burns.    There are additional dangers even when working with low voltage and large cable cross-sections. Cables with a large cross-section generally have lower voltages, although the amperages are higher.    •   Before starting any work, check that the circuits involved are de-energized. Never take it for granted that turning off a main switch or circuit breaker will reliably interrupt all circuits.  •   Only use systems, tools, and equipment which are in perfect condition. Do not use equipment with visible damage.  •   Replace any damaged safety equipment (covers, labels and ground wires) immediately.  •   Replace the power cable immediately if you notice any damage.  •   Only place systems or devices in protection class I into operation using a ground contact socket.  •   Connect the communication system and, if necessary, the main distribution frame to the ground wire before starting up the system and connecting telephones and lines. Never operate the communication system without the required ground wire.  •   Never touch live wires without ensuring adequate insulation.  •   Do not carry out any hardware installation work on telecommunication systems and devices during a storm.  •   Expect leakage current from the telecommunications network. Disconnect all telecommunication lines from the system before disconnecting the prescribed ground wire from the system.

WARNING   Disconnection from power circuit(s)   A disconnect device can be a disconnecting switch (main switch), circuit breaker (fuse/cutout), or power plug that completely disconnects the telecommunication system and device from the power circuit.    •   Before carrying out any work on the communication system or on the device, find out whether there is a disconnect device and locate it.  •   When you need to disconnect the power supply to the communication system or device, you do so using the disconnect device.  •   Secure the disconnect device mechanically so that it cannot be used by other persons and attach a sign reading DO NOT OPERATE to the disconnect device.  •   Ensure that the communication system or device is not powered from an additional power source (for example, an uninterruptible power supply), or that it is protected by an additional fuse or an additional main switch.   •   If you are performing work on circuits with hazardous voltages, always work together with a partner who is familiar with the location of the disconnect devices for the power supplies.  •   Always disconnect the power supply when you are working directly next to a power supply unit or direct current converter, unless the work instructions expressly permit you to work without disconnecting the power supply.  •   High voltages capable of causing shock are used in this equipment. Be extremely careful when measuring high voltages and when servicing cards, panels, and boards while the system is powered on.  •   Metallic surfaces such as mirrors are conductive. If you touch them, there is a risk of electric shocks or short circuits.