Cisco 4948 Installation Guide - Page 40

Power Requirements Chapter 2 Preparing for Installation Power Connection Guidelines for AC-Powered Systems This section provides some basic guidelines for connecting the AC power supplies to the site power source: • Each chassis power supply should have a separate, dedicated branch circuit. • For North America: - The 300 W power supply requires a 15 A circuit. • For International: - Circuits should be sized according to local and national codes. • If you are using a 200/240 VAC power source in North America, the circuit must be protected by a two-pole circuit breaker. • The source AC outlet must be within 6 feet (1.8 meters) of the system and should be easily accessible. • The AC power receptacles used to plug in the chassis must be the grounding type. The grounding conductors that connect to the receptacles should connect to protective earth ground at the service equipment. Power Connection Guidelines for DC-Powered Systems This section provides the basic guidelines for connecting the Catalyst 4948E switch DC-input power supplies to the site power source: • All power connection wiring should conform to the rules and regulations in the National Electrical Code (NEC), as well as any local codes. • The DC return must remain isolated from the system frame and the chassis (DC-I). • For DC power cables, we recommend that you use commensurately rated, high-strand-count copper wire cable. Connection to the DC-input power supply requires one earth ground cable, one source DC (-), and one source DC return (+). The length of the cables depends on your switch location. The cables and the lugs required to attach the source DC cables to the power supply are not available from Cisco Systems. They are available from any commercial cable vendor. • The color coding of the source DC power cable leads depends on the color coding of the site DC power source. Typically, green or green and yellow indicate that the cable is a ground cable. Because there is no color code standard for source DC wiring, you must ensure that the power cables are connected to the DC-input power supply terminal block in the proper (+) and (-) polarity. In some cases, the source DC cable leads might have a positive (+) or a negative (-) label. This label is a relatively safe indication of the polarity, but you must verify the polarity by measuring the voltage between the DC cable leads. When making the measurement, the positive (+) lead and the negative (-) lead must always match the (+) and (-) labels on the DC-input power supply terminal block. • DC power cables must be terminated by cable lugs at the power supply end. • The circuit breaker is considered to be the disconnect device and should be easily accessible. • The circuit must be protected by a dedicated two-pole circuit breaker. The circuit breaker should be sized according to the power supply input rating and local or national code requirements. 2-12 Catalyst 4948E and Catalyst 4948E-F Switch Installation Guide OL-21561-02