J-BOX - Abbreviation for junction box. A box for joining different runs of raceway or cable, plus space for connecting and branching the enclosed conductors.
JACKET - A covering over insulation usually nonmetallic, plastic, rubber, cotton, Neoprene®, fluoropolymer, or glass. Neoprene® is a trademark of the DuPont de Nemours Co.
JAN-C-17A - Joint Army-Navy specifications covering coaxial cables used for high frequency applications in radio, television, radar, etc.
JAN-C-76A - Joint Army-Navy specifications covering radio hook-up wire. Types SRIR, SRHV, WL, and SRRF. Superseded by MIL-W-76.
JOULE - The unit of measure for energy or work. The international joule is equal to the work required to maintain a current of one ampere for one second in a resistance of one ohm.
JUMPER - Usually a temporary connection. A short length of conductor to connect between terminals, across a break in a circuit, or around an instrument.
JUTE FILLER - Rope like strands of material used in cables for filling in the voids to form a rounded final cable shape.