General safety practices, Connection of ac mains, Connection of dc mains – RAD Data comm ASM-20 User Manual
Page 6: Handling energized products
Handling Energized Products
General Safety Practices
Do not touch or tamper with the power supply when the power cord is connected. Line voltages may be
present inside certain products even when the power switch (if installed) is in the OFF position or a fuse is
blown. For DC-powered products, although the voltages levels are usually not hazardous, energy hazards
may still exist.
Before working on equipment connected to power lines or telecommunication lines, remove jewelry or any
other metallic object that may come into contact with energized parts.
Unless otherwise specified, all products are intended to be grounded during normal use. Grounding is
provided by connecting the mains plug to a wall socket with a protective earth terminal. If an earth lug is
provided on the product, it should be connected to the protective earth at all times, by a wire with a
diameter of 18 AWG or wider. Rack-mounted equipment should be mounted only in earthed racks and
cabinets.
Always make the ground connection first and disconnect it last. Do not connect telecommunication cables
to ungrounded equipment. Make sure that all other cables are disconnected before disconnecting the
ground.
Connection of AC Mains
Make sure that the electrical installation complies with local codes.
Always connect the AC plug to a wall socket with a protective ground.
The maximum permissible current capability of the branch distribution circuit that supplies power to the
product is 16A. The circuit breaker in the building installation should have high breaking capacity and must
operate at short-circuit current exceeding 35A.
Always connect the power cord first to the equipment and then to the wall socket. If a power switch is
provided in the equipment, set it to the OFF position. If the power cord cannot be readily disconnected in
case of emergency, make sure that a readily accessible circuit breaker or emergency switch is installed in the
building installation.
In cases when the power distribution system is IT type, the switch must disconnect both poles
simultaneously.
Connection of DC Mains
Unless otherwise specified in the manual, the DC input to the equipment is floating in reference to the ground.
Any single pole can be externally grounded.
Due to the high current capability of DC mains systems, care should be taken when connecting the DC supply
to avoid short-circuits and fire hazards.
DC units should be installed in a restricted access area, i.e. an area where access is authorized only to
qualified service and maintenance personnel.
Make sure that the DC supply is electrically isolated from any AC source and that the installation complies
with the local codes.
The maximum permissible current capability of the branch distribution circuit that supplies power to the
product is 16A. The circuit breaker in the building installation should have high breaking capacity and must
operate at short-circuit current exceeding 35A.
Before connecting the DC supply wires, ensure that power is removed from the DC circuit. Locate the
circuit breaker of the panel board that services the equipment and switch it to the OFF position. When
connecting the DC supply wires, first connect the ground wire to the corresponding terminal, then the
positive pole and last the negative pole. Switch the circuit breaker back to the ON position.
A readily accessible disconnect device that is suitably rated and approved should be incorporated in the
building installation.
If the DC mains are floating, the switch must disconnect both poles simultaneously.