Electrical Supplies…
Electrical Code…
Three or more flat copper conductors placed edge-to-edge and separated and enclosed within an insulating material.
FCC System: A complete wiring system for branch circuits that is designed for installation under carpet squares. The FCC system includes Type FCC cable and associated shielding, connectors, terminators, adapters, boxes, and receptacles.
Top Shield: A grounded metal shield covering undercarpet components of the FCC system for the purposes of providing protection against physical damage.
Bottom Shield: A protective layer that is installed between the floor and Type FCC flat conductor cable to protect the cable from physical damage and may or may not be incorporated as an integral part of the cable.
Construction: Type FCC cable shall be listed for use with the FCC System and shall consist of three, four, or five flat copper conductors, one of which shall be an equipment grounding conductor.
All top and bottom shields shall be of designs and materials identified for their use. Top shields shall be metal. Both metallic and nonmetallic materials shall be permitted for bottom shields.
(National Electrical Code® 324.2, 324.100)
NT Commentary…
Flat Conductor Cable, Type FCC:
You get the picture. This is a cable assembly designed to be installed beneath carpet squares in an office or institutional setting. It provides an ability to extend wiring out into an open environment and feed floor receptacles or transition the circuit to office partition panels. This enables easier changes to the layout of office furniture etc.
The top protective shield per code has to be made of metal to prevent things like silicon valley yuppy-types from sticking their gold-plated envelope openers through the carpet and penetrating the conductors, while the bottom shield can be of either approved metallic or nonmetallic stuff.
As always check your NEC (Article 324) and supplier for more info.
(NT)