The Railway Technical Website

NEMA L6 connectors are rated for a maximum of 250 volts. NEMA L2 series devices are two-pole, two-wire, non-grounding devices for 250 volts single-phase. They are intended for two-pole, three wire, line-line-earth (or hot-hot-ground) circuits with a nominal supply voltage of 208 or 240 volts, depending on phase configuration. RVs in the US are equipped for 120 V 30 A or 240 V 50 A service, and use a cord to connect to a receptacle at the campsite, usually on a power pedestal with one or more receptacles providing 120 V 30 A (TT30R), 240 V 50 A (14-50R), or 120 V 15/20 A (5-20R) service. NEMA L14 are three-pole and ground connectors rated for 125/250 V. Intended for three-pole, four-wire hot-hot-neutral-ground circuits with a nominal supply voltages of 240 or 208 V hot-to-hot and 120 V hot-to-neutral. Utilities add capacitor banks, reactors and other components (such as phase-shifters; static VAR compensators; and flexible AC transmission systems, FACTS) throughout the system help to compensate for the reactive power flow, reduce the losses in power transmission and stabilize system voltages. As with any "uniform" code, jurisdictions may regularly omit or modify some sections, or add their own requirements (sometimes based upon earlier versions of the NEC, or locally accepted practices).

One apparent disadvantage of twist-lock connectors is that in the event that the cable is accidentally pulled too hard, rather than the plug falling out of the receptacle, exposed conductors may come out of the plug, causing dangerous shorts or shock hazards if the circuit is live. This was invented in 1930, but not available outside military use until after World War 2 during which a telegraph cable using it was laid across the English Channel to support troops following D-Day. Before the war the Government saw no need to connect lines within city limits, however, they did see the use in connections between cities. During the 1950s, some electric lines began to be installed in tunnels, expanding the scope of the work. The motoring group said just one in six English councils have installed on-street charge points in residential areas after a total of 316 from 353 authorities replied to a recent freedom of information request it issued. L6-20 connectors provide a maximum of 20 amperes and are commonly found in power distribution units (PDUs) used in the information technology sector. Most often, these connectors can be found in server rooms and data centers where the connectors are used to power equipment such as servers, backup systems and UPS units.

NEMA L7 are two-pole and ground connectors rated for 277 V. Typically, these connectors are found in commercial or industrial lighting circuits, what is electric cable especially where metal halide lamps are common. NEMA L5 connectors are a series of two-pole and ground locking connectors rated for 125 V. L5-30R receptacles are common at marinas that provide power to docked boats. NEMA L9 are two-pole and ground connectors rated for 600 V. Intended for three-wire hot-hot-ground circuits. NEMA L18 are four-pole no ground connectors rated for 120/208 V. Intended for wye three-phase circuits. NEMA L22 are four-pole and ground connectors rated for 277/480 V. Intended for wye three-phase circuits with both neutral and ground. NEMA L21 are four-pole and ground connectors rated for 120/208 V. Intended for wye three-phase circuits with both neutral and ground. NEMA L23 are four-pole and ground connectors rated for 347/600 V. Intended for wye three-phase circuits with both neutral and ground. NEMA L17 are three-pole and ground connectors rated for 600 V. Intended for three-phase circuits.

NEMA L15 are three-pole and ground connectors rated for 250 V. Intended for three-phase circuits. NEMA L16 are three-pole and ground connectors rated for 480 V. Intended for three-phase circuits. This allows for cost-effective retrofits on older installations where branch circuits were often daisy-chained between wet and dry locations. For drivers with street parking only, there is something called the On-Street Residential Charging Scheme (ORCS), which allows owners of plug-in cars to write to their council to ask for them to install local charging devices. Locking connectors come in a variety of standardized configurations that follow the same general naming scheme except that the designations include an "L" for "locking". These benefits come with a trade-off of typically being double or triple the price of a comparable Monocable system. To ensure safe and predictable operation, system components are controlled with generators, switches, circuit breakers and loads. The most basic cable system operates on one single cable loop, while others have multiple loops as well as several stationary cable lines. Over time, electrical codes in the US and Canada began to require additional safety features in the basic NEMA 5-15R and 5-20R configurations to address specific electric shock hazard concerns. Many specific types exist; only a few are listed below.