| UF |
Thermoplastic underground feeder and branch circuit cable |
| UHF |
Abbreviation for Ultra High Frequency, 300 to 3000 MHz |
| UL |
Abbreviation for Underwriters Laboratories, a non-profit independent organization, which operated a listing service for electrical and electronic materials and equipment |
| Unbalanced circuit |
A transmission line in which voltages of the 2 conductors are unequal with respect to ground |
| Unilay |
More than one layer of helically laid wires with the direction of lay and length of lay the same for all layers |
