DC Power Wiring Sequence Warning
WARNING: Wire the DC power supply using the appropriate lugs. When connecting power, the proper wiring
sequence is ground to ground, +RTN to +RTN, then –48 V to –48 V. When disconnecting power, the proper
wiring sequence is –48 V to –48 V, +RTN to +RTN, then ground to ground. Note that the ground wire should
always be connected first and disconnected last.
DC Power Wiring Terminations Warning
WARNING: When stranded wiring is required, use approved wiring terminations, such as closed-loop or spade-
type with upturned lugs. These terminations should be the appropriate size for the wires and should clamp
both the insulation and conductor.
Cable and Wire Guidelines
Distance Limitations for Signaling
Improperly installed wires can emit radio interference. In addition, the potential for damage from lightning
strikes increases if wires exceed recommended distances, or if wires pass between buildings. The
electromagnetic pulse (EMP) caused by lightning can damage unshielded conductors and destroy electronic
devices. If your site has previously experienced such problems, you might want to consult experts in electrical
surge suppression and shielding.
Radio Frequency Interference
You can reduce or eliminate the emission of radio frequency interference (RFI) from your site wiring by using
twisted-pair cable with a good distribution of grounding conductors. If you must exceed the recommended
distances, use a high-quality twisted-pair cable with one ground conductor for each data signal when
applicable.
Electromagnetic Compatibility
If your site is susceptible to problems with electromagnetic compatibility (EMC), particularly from lightning
or radio transmitters, you might want to seek expert advice. Strong sources of electromagnetic interference
(EMI) can destroy the signal drivers and receivers in the services gateway and conduct power surges over the
lines into the equipment, resulting in an electrical hazard. It is particularly important to provide a properly
grounded and shielded environment and to use electrical surge-suppression devices.
CAUTION: To comply with intrabuilding lightning/surge requirements, intrabuilding wiring must be shielded,
and the shield for the wiring must be grounded at both ends.
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