Current through Register Vol. 54, No. 45, November 9, 2024
Section 39.144 - Guarding conductors(a)Use of enclosed casings. If insulated conductors are enclosed, suitable permanently grounded metal conduit or grounded metal sheating shall be used; or in lieu thereof other ducts, runways, or compartments of tile, bitumenized fiber, concrete, or other suitable fire-resistive materials may be used, if containing no exposed combustible material. In damp places, conduits, ducts, or runways shall be made waterproof and be provided with suitable means for draining off condensation, unless the conductors contained are lead-sheathed cables.(b)Conductors above 750 volts in conduits or sheathing. Conductors operating at over 750 volts unless separately supported and effectively isolated by elevation or by enclosing in suitable compartments or screens, as in subsection (d), shall be suitable metal sheathed cable, run in metal conduits or suitable fire-resistive ducts or compartments, with the metal sheathing permanently grounded. Other covering may be used in suitable grounded metal conduit or insulating duct, when installed in dry locations. The conduit or duct shall provide a smooth runway with smooth outlets. Metal conduit, if used, shall be made electrically and mechanically continuous with the metal casings of conduit fittings.(c)Metal sheathed cable outlets above 750 units. Insulation of the several conductors of multiple conductor cable, where leaving the metal sheath at outlets, shall be thoroughly protected from mechanical injury, moisture and electrical strains by means of a pot head or equivalent method.(d)Open conductors above 750 volts. When any open insulated conductor above 750 volts, or any open bare conductor above 300 volts to ground, is necessarily brought closer to the floor line than the clearances required for isolation by elevation, they shall be guarded by permanent screens, by enclosing partitions, or by suitable barrier guards.(e) If barrier rails only are used, the surrounding floors shall be provided with suitable insulating platforms, mats, or covers. Reference should also be made to § 39.105(b) (relating to guarding live parts). This section cited in 34 Pa. Code § 39.143 (relating to isolation by elevation).