Special Systems

There are specific requirements for special systems, such as those that operate over 600 volts, nominal, interrupting and isolating devices, mobile and portable equipment, and tunnel installations.

Above-Ground Conductors

Above-ground conductors must be installed in specific ways, such as:

• In a rigid metal conduit
• In an intermediate metal conduit
• In cable trays
• In a cable-bus
• In other suitable raceways
• As open runs of metal-clad cable

Metallic shielding components must be grounded, including the following:

• Tapes
• Wires
• Braids for conductors

Open runs of insulated wires and cables with a bare lead sheath or a braided outer covering must be supported in a way that will prevent physical damage to the braid or sheath.

Conductors emerging from the ground must be enclosed in raceways.

Raceways installed on poles must be made of specific material, such as the following:

• Rigid metal conduit
• Intermediate metal conduit
• PVC schedule 80 or equivalent, extending eight feet up from the ground line

Conductors entering a building must be protected by an enclosure from the ground to the point of entrance, and metallic enclosures must be grounded.

To learn more about Construction Electrical Safety visit our Construction Electrical Safety Online Training web page.