Open as Applied to Electrical Equipment - Means that moving parts, windings, or live parts are exposed to accidental contact.
Ohm - The unit of measure for resistance.
Ohm's Law - Voltage equals resistance multiplied by current.
Oil - When relating to a liquid-filled transformer, refers to mineral oil.
Optical Fiber Cable - a cable consisting of
one or more optical fibers that transmits modulated light for the
Oscillogram - A record made of an oscillograph.
Oscillograph - A device used for recording and measuring the instantaneous values of a rapidly varying electrical quantity as shown by its corresponding waveform.
Outlet - A point in the wiring installation at which current is taken to supply utilization equipment.
Outline Lighting - An arrangement of incandescent lamps or electric discharge tubing to outline or call attention to certain features such as the shape of a building or the decoration of a window.
Overcurrent Device - Any device capable of automatically opening an electric circuit, under both predetermined overload and short-circuit conditions, either by fusing of metal or by electro-mechanical means.
Overload device - A device affording protection from excess current, but not necessarily short-circuit protection, and capable of automatically opening an electric circuit either by fusing of metal or by electro-mechanical means.
Overvoltage - A voltage above the normal rated voltage or the maximum operating voltage of a device or circuit. A direct test overvoltage is a voltage above the peak of the line alternating voltage.
|Source: Canadian Electrical Code and National Electrical Code|