UPS Plug Types and Information
All NEMA 1 devices are two-wire non-grounding devices rated for 125 V maximum. NEMA 1-15P plugs have two parallel flat blades,
1/4 inches (6.35 mm) wide, 0.06 inches (1.524 mm) thick, 5/8–23/32 inches (15.875–18.256 mm) long,
and spaced 1/2 inches (12.7 mm) apart, and are commonly found on household lamps and consumer electronics such as clocks and radios.
Standards exist for 1–15P, 1–20P and 1–30P plugs, and the 1–15R receptacle.
There are no 1–20R and 1–30R receptacles; 1–20P and 1–30P mate with a corresponding NEMA 5 receptacle.
Plugs and receptacles may be polarized to preserve the identity of the neutral conductor;
the blade connected to neutral will be wider (5/16 in/7.938 mm) than the other,
and polarized sockets will only accept a polarized plug in the correct orientation.
All NEMA 5 devices are three-wire grounding devices rated for 125 V maximum and are non-locking connectors.
The 5–20R receptacle may have a T-shaped neutral hole, to accept both 5–15P and 5–20P plugs.
The 5–30 and 5–50 are uncommon, as twist-locking plugs are generally used for high-current applications.
They are larger, with 1 inch between power pins.
All NEMA 6 devices are three-wire grounding devices used for 208 V and 240 V circuits and rated for 250 V maximum and are non-locking connectors.
The 6–20R receptacle may have a T-shaped hole, to accept both 6–15P and 6–20P plugs.
The higher-current versions are rare, as twist-locking plugs are generally used for high-current applications.
NEMA 6 devices, while specified as 250 V, may be used for either 208 V or 240 V circuits, generally depending on whether the building has a three-phase or
split-phase power supply.
NEMA L5 connectors are a series of locking connectors with a maximum specified voltage of 125V.
Supply connections are intended to be single-pole L-N-G circuits with a nominal voltage of 120V RMS.
The L5–30 is a very popular configuration even on circuits not requiring the 30A current capacity, owing to its very rugged construction.
L5-20P and L5-30P are commonly used for in-rack power distribution units in the US.
NEMA L6 connectors are a series of locking connectors used with circuits with a maximum specified voltage of 250V.
Supply connections are intended to be two-pole, three wire L-L-G circuits with nominal supply voltage of 240V or 208V depending on phase configuration.
L6-20 and L6-30 connectors are commonly found on in-rack power distribution units in countries where the mains supply voltage is greater than 120V, and in
the US where equipment load is such that the system would benefit from a higher supply voltage (and thus, lower current draw).
NEMA L14 connectors are a series of locking connectors used with circuits with a maximum specified voltage of 125/250V.
Supply connections are intended to be two-pole, four-wire L-L-N-G circuits with a nominal supply voltages of 240V or 208V L-L and 120V L-N.
NEMA L15 connectors are a series of locking connectors used with circuits with a maximum specified voltage of 250V AC.
Supply connections are intended to be three-phase, four-wire L-L-L-G circuits with a nominal supply voltage of 208V L-L (standard low-voltage three phase) or
240V L-L (delta three phase).
NEMA L21 connectors are used with circuits with a maximum specified voltage of 120/208V AC.
Supply connections are intended to be three-phase, five-wire L-L-L-N-G circuits with a nominal supply voltage of 208V L-L and 120V L-N.
These three-phase connections include neutral and ground.
The pin in the middle is ground, and the blade with a right angle on the tab is neutral.
IEC C13/14 Connectors are a 3-conductor 10 A cable, most commonly used with computers and monitors.
C19 and C20 connectors, with pins rated at 16 A, are used for some server room applications where higher currents are required, for instance, on high-power
servers, UPSs, PDUs and similar datacenter equipment.
They are similar to C13 and C14 connectors, but rectangular (without chamfered corners) and with slightly larger pins, rotated so they are parallel to the
long axis of the connector.
These are commonly used on larger Cisco catalyst switches, larger servers by HP and Sun, and blade enclosures.