Nortel Networks Option 11C Mini Conduit requirements, Chassis powered by different service panels

Page 54 of 332 Chapter 3 — System and site requirements

Chassis powered by different service panels

For each Main Chassis, connect a #6 AWG (#40 Metric Wire Gauge) ground wire from the chassis to the NTBK80 grounding block. See Table 10 on page 49 for grounding wire requirements specific to some areas. If any chassis cannot be powered from the same service panel, ground it separately from the other chassis back to the service panel that supplies it. Power each Main Chassis and Chassis Expander pair from the same service panel.

Note 3: If a chassis requires a separate ground, ground it using the same method that you use for a system with one chassis.

Note 4: In the UK, you can connect the grounding wire from the chassis to an NTBK80 grounding block or through a Krone Test Jack Frame.

Grounding multiple pieces of equipment in a rack/cabinet

You must ground each piece of equipment in a rack/cabinet. If a piece of equipment does not have a ground lug, then ground the whole rack/cabinet.

Conduit requirements

Conductive conduit linking panels and equipment are legal for use as a grounding network in most countries. For all system ground paths for the Option 11C Mini, use the correct size of insulated copper conductors routed inside conduit when possible. A ground link that depends on conduit can defeat the improvements made by installing dedicated panels and transformers. The following are the reasons why:

•Personnel who service different equipment can separate conduit links. If this separation occurs between the Option 11C Mini system and the building ground reference, the conduit cannot provide a ground path. This situation is a hazardous.

•Metal conduit often corrodes, especially at threaded connections. Corrosion increases resistance. This problem becomes worse when multiple links are involved. If you apply paint over the conduit, it is possible that the corrosion process will occur more quickly.

•Always fasten conduit to secure surfaces. Often, conduit is bolted to structural steel members, which can function as ground conductors to noisy equipment (for example, compressors and motors). The coupling of these noisy signals into the Option 11C Mini grounding system can damage its performance. The resulting intermittent malfunctions can be difficult to trace.

553-3021-209 Standard 3.00 April 2000