then another code-approved method must be used. (The isolated ground conductor is noted in the National Electrical Code{ XE "National Electrical Code" }{ XE "NEC" \t "See National Electrical Code" }, Section 250-74, Exception 4.) Use of an isolated ground rod or grounding to a water pipe is not acceptable.
An isolated/insulated ground conductor, equal to or larger in size than the heaviest gauge AC feeder conductor in the circuit, should be bonded to the ground bus in the building main power panel. Route it with the circuit conductors in the wiring conduit. Pass this ground through any intermediate panel boards without connection to the panel board grounding terminal bars. The National Electric Code, cited above, allows for the installation at the intermediate panel board of an isolated ground bus, constructed from a terminal block kit, for the interconnection of the isolated ground conductor.
This isolated/insulated ground conductor runs as a single, uninterrupted circuit between the building main power panel and the 5000i system branch power panel. It forms the interconnection point for the third-wire { XE "Ground:Third-wire" \i }grounds of all 5000i system components. Connect all 5000i system component third-wire grounds to this ground; do not connect any equipment other than 5000i system components to this ground conductor. This condition is met if all system components are plugged into the { XE "Switched convenience outlet" \t "See Convenience outlet" }switched convenience outlet{ XE "Convenience outlet:switched" }{ XE "Electrical outlet, convenience" \t "See convenience outlet" \i }{ XE "Outlet, convenience" \t "See Convenience outlet" } in the base of the scanner.
1)At some sites, local regulations require that all installed equipment be connected to a system common ground. In this case, connect all 5000i system components to the common ground at only one point. Connect third wire grounds of system components onto a common bus that is connected to the common ground at a single point.
2)Make sure the equipment third-wire { XE "Ground:Third-wire" \i }ground (green wire) does not become connected to the conduit at the outlet box or connector. To avoid an inadvertent connection, use a NEMA 5-20R type isolated-ground receptacle, such as a
Hubble IG-5362.
Grounding in Multi-Story Buildings{ XE "Grounding:In multistory building" \i }
When installing the 5000i system in a multi-story building{ XE "Multistory building, grounding" \t "See Grounding in multistory building" }, provide a low noise ground by connecting the isolated { XE "Conductor:Isolated/insulated" }ground { XE "Ground:Conductor" \i }of the system to the structural steel of the building. Install the isolated ground system as described above. In addition, bond one end of a heavy gauge wire or copper braid to the isolated ground bus in the branch circuit panel serving the 5000i system. Weld the other end of this wire or braid to the nearest vertical steel structural member. Do not substitute a water pipe or an isolated ground rod for the vertical steel member.
Page 12 | 5000i Scanner Installation Guide |
