NEMA 6
All NEMA 6 devices are three-wire grounding devices (hot-hot-ground) used for 208 V and 240 V circuits and rated for 250 V maximum, with the 615, 620 and 630 being grounding versions of the 215, 220 and 230, respectively. The 6-15 resembles the 5-15, but with collinear horizontal pins, spaced 23⁄32 in (18.256 mm) center-to-center. The 20 A plug has a blade rotated 90°, and the 620R receptacle may have a T-shaped hole, to accept both 615P and 620P plugs. The 30 A plug and socket look similar to the 15 A one but larger. The higher-current versions are rare, with twist-locking plugs such as L6-30 or direct wiring more common. Generally 6series non-locking plugs are used for such appliances as large room air conditioners, commercial kitchen equipment, and the occasional home arc welder. Single phase 6-50 is commonly used on farms for the silo unloader, and is used with a 6 gauge flexible power cord up to 200 ft long (61 m).
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. The NEMA 620R or 630R found in many hotel rooms is often supplied with 208 V and without a neutral.