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NEMA 6 devices, while specified as 250 V, may be used for either 208 or 240 V circuits, generally depending on whether the building has a three-phase or split-phase power supply, respectively. The NEMA 6-20R or 6-30R found in many hotel and motel rooms is typically supplied with either split-phase or two phases of three-phase 208 V.
120 V circuits are the most common, and used to power NEMA 1 and NEMA 5 outlets, and most residential and light commercial direct-wired lighting circuits. 240 V circuits are used for high-demand applications, such as air conditioners, space heaters, electric stoves, electric clothes dryers, water heaters, and electric vehicle charge points.
The hazard of this is that if single phase loads are connected to the high leg (with the connecting person unaware that leg is higher voltage), excess voltage is supplied to that load. This can easily cause failure of the load. Commonly there is a high-leg to neutral load limit when only two transformers are used. [6]
Ratings of NEMA 5-15 (type B) plug marked on the label (left: 7 A 125 V), engagement face, and IEC 60320 C13 connector at the appliance end of the cord (centre, right: both 10 A 125 V) Plugs and power cords have a rated voltage and current assigned to them by the manufacturer. Using a plug or power cord that is inappropriate for the load may be ...
Lighting and general purpose receptacles are at 120 volts AC, with larger devices fed by three wire single-phase circuits at 240 volts. In commercial construction, three-phase circuits are often used. Common 3 phase configurations within a building are 208v/120 wye, 120/240 center tapped delta and 480v/277v wye. Lighting is usually fed by 277 V ...
This allows one to choose single-phase AC power at either 110–120 volts between phase and neutral or 220–240 volts between phase and phase. Since these two modes do not need three phases there is also a dark yellow-orange four-pin connector available designed for a single-phase 110–120 or 220–240 volt load.
NEMA (National Electrical Manufacturers Association) contactors and motor starters are rated by sizes. These sizes are grouped by rated current and power . [ 1 ] [ 2 ]
The low-voltage secondary windings are attached to three or four terminals on the transformer's side. In North American residences and small businesses, the secondary is often the split-phase 120/240-volt system. The 240 V secondary winding is center-tapped, and the center neutral wire is grounded, making the two end conductors "hot" concerning ...