SITE PREPARATION2-5Edition OneXC1000 Service2.4.3 GroundingXC1000 uses a single-point ground for electrical safety and a ground-referenced power input for proper operation of the telephony signalingcircuits. When preparing the site, prepare the frame ground wire so that itis ready for attachment to the XC1000 when the XC1000 is installed. Usethe guidelines to prepare the frame ground wire: Ground each primary cabinet frame properly with a single-conductorframe grounding wire. Ensure that this wire is connected to earth groundor an equivalent safety ground, such as building steel, water pipe, orgrounding bar in a branch circuit power panel. This ground connectionmust comply with all local, state, and national electrical codes. Ground each expansion cabinet frame mechanically and electrically toa properly grounded primary-cabinet frame. Make sure that all grounding conductors are the same diameter as orlarger than the conductors used to carry input power. Do not rely on electrical circuits for frame grounding. The safety ground should have a dc resistance to ground of 0.1 ohmsor less. Always size and route the ground conductor to stay below thisresistance specification. Use the two-point compression (or optionalswag) grounding lug supplied with the primary cabinet to connect theground wire to the frame.The XC1000 was designed to be installed as an isolated ground load usinga single-point grounding system. Connect each XC1000 frame (single ordual cabinet) separately to the nearest safety-ground bus in the buildingwithout bridging or chaining to adjacent equipment. In a dual-cabinetsystem, connect and ground the expansion cabinet to the primary cabinetonly. To ensure that the single-point ground is achieved, the XC1000 floormounts use a mylar barrier sheet that provides at least 10 megohmsisolation resistance between the frame and the floor.Ground reference all telephony signaling circuits by ground referencing theinput power to the XC1000. The –48-Vdc power return lead (labeled + onthe main power-input terminal block), which runs back to a power source ordistribution panel, is strapped to the CO main ground bus. This ground busmight be the same as the safety ground used to connect the XC1000 frameto ground. The strap is usually installed as close to the power source ordistribution panel as practical, but it operates with equal effectiveness iflocated at the XC1000 end of the power wiring configuration.2.5 POWER REQUIREMENTSXC1000 requires input power of –48 Vdc. The –48 Vdc power is availablewhen the XC1000 is installed on switching-office premises. In some cases,where the XC1000 is installed at another location, –48 Vdc might not beSECTION 2.4 – 2.5
