J

K

L

L-L - Abbreviation for line-to-line

L-G - Abbreviation for line-to-ground

L-N - Abbreviation for line-to-neutral

LAN - Abbreviation for local area network

LED - Abbreviation for light emitting diode

LEMP - Abbreviation for lightning electromagnetic pulse

Let-through voltage - The part of a transient overvoltage that is allowed through a protector. It is important to remember that the let-through voltage is the sum of the voltage drop across the surge protector itself plus the voltage drops that appear across the wiring that connects the protector to the power lines. The protector clamping voltage is only one part of the let-through voltage and frequently is of secondary importance to the wiring drop.

Lightning electromagnetic pulse (LEMP) - A disturbance produced by the electromagnetic field caused by a lightning discharge and resulting in transient overvoltages.

LPS - Abbreviation for lightning protection system

Lightning protection system (LPS) - The whole system of lightning conductors and earth connections used to protect a building or structure from the effects of a direct lightning strike.

Live - A conductor or circuit which is not at earth potential and is therefore carrying a voltage

Load - Equipment or devices drawing power from a power source. Also the output side of a power source.

Local area network (LAN) - A communication system that links many computers, printer, data storage devices, and the like, together within a building or plant (e.g.. Ethernet).

Longitudinal - The voltage that appears between each of two or more conductors and earth. See common mode.

Low voltage (LV) - Voltage not exceeding 1,000 AC or 1,500 DC between conductors (L-L or L-N), or 600 volts AC or 900 volts DC between conductors and earth (L-G or N-G).

LV - Abbreviation for low voltage