Respuesta :
Flexible cord sets and power-supply cords shall not be concealed behind building , structural ceilings, suspended or dropped ceilings, floors or walls, or run through doorways, windows, or similar openings.
Hence Option (b) All of these is correct
Flexible cord and flexible cable usage are now outlined in Section 400.10, while prohibited uses are listed in Section 400.12.
Note 5 under 400.12 now includes a new exclusion for flexible wires and cords (uses not permitted).
Flexible cables, flexible cord sets, and power supply cords are not permitted in areas that are "concealed by walls, floors, or ceilings or positioned above suspended or dropped ceilings," according to Note 5.
The following uses for flexible cables, flexible cord sets, and power supply cords are prohibited as well:
(1) As an alternative to a structure's fixed wiring.
(2) Run-through openings in structural ceilings, floors, suspended ceilings, or dropped ceilings.
(3) When run through windows, doorways, or comparable openings.
(4) If attached to building surfaces.
Hence, Option (b) All of these is correct .
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