The conductors and connectors covered here are only those used in unconventional applications.

10.10.3.1 HAZARDS

Examples of hazards are as follows:

1. Metallic cooling-water pipes that are also used as electrical conductors present shock hazards (i.e., they may not be readily recognizable as electrical conductors).

2. Improper application or installation of connectors can result in overheating, arcing, and shock hazards.

3. Hazardous induced voltages and arcing can result from inadequate separation between highand low-voltage cables.

4. Use of an improper cable for a given type of installation (routing) can result in a fire hazard.

10.10.3.2 DESIGN AND CONSTRUCTION

When working with special conductors and connectors for R&D applications, the following guidelines shall be implemented for design and construction:

1. Select cables that are listed by an NRTL for a given type of installation (such as in conduits, trays, underground, or in an enclosure) whenever possible. Since cables used for R&D are sometimes unique (such as some coaxial cables), they may not be available as NRTL listed. In that case, obtain AHJ approval.

2. Where liquid- or gas-cooled conductors are used, sensing devices (temperature or coolantflow) shall be provided for alarm purposes or equipment shutdown if the cooling system malfunctions. Provide adequate labeling, insulation, or other protection for metallic coolingwater piping used as electrical conductors.

3. Provide engineering calculations to support overrating of conductors for any application. Avoid conductor loops (wide spacing) between high-current supply and return conductors to prevent voltage and current induction in adjacent circuits or structural members.

4. Ground coaxial cable shielding when possible. If test conditions require an ungrounded shield, provide barriers and warning signs to notify personnel that the shield is ungrounded and should be assumed to be energized. Provide suitable routing and additional protection for coaxial cables used in pulsed-power applications where the braid of the coaxial cable rises to high voltage levels.

10.10.3.3 OPERATION AND MAINTENANCE

Cable connectors and connections should be checked after installation, periodically, and should be tightened as necessary. Special attention should be given to aluminum cable connections.

Ensure that charges are not built up on equipment that has been disconnected, such as vacuum feedthrough systems.