RME Board Exam key terms

The rule that current through a resistance equals the voltage across it divided by its resistance (I = V/R), and that voltage equals current times resistance; the basis for solving circuit values.

The principle that all current entering a junction must equal all current leaving it, since charge cannot pile up at a point; used to solve parallel and multi-branch circuits.

The principle that the sum of all voltage rises and voltage drops around any closed circuit loop equals zero; used to analyze series and multi-loop circuits.

The ratio of real power in watts to apparent power in volt-amperes in an AC circuit; it ranges from 0 to 1 and shows how effectively the current does useful work.

The total opposition that a circuit offers to alternating current, combining resistance and reactance into a single value measured in ohms.

The part of impedance caused by inductance or capacitance, measured in ohms; it depends on frequency and shifts current out of phase with voltage.

A connection in which components are joined end to end so the same current passes through each one, and the supply voltage equals the sum of the individual voltage drops.

A connection in which each component is placed across the same two points, so every branch has the same voltage and the total current is the sum of branch currents.

The effective value of an alternating current or voltage: the steady DC value that would produce the same heating effect. For a sine wave it is the peak divided by 1.414.

The loss of voltage along conductors carrying current, caused by their resistance and reactance; too much drop causes dim lamps, slow motors, and overheating.

An accidental low-resistance contact between two points at different voltage, allowing abnormally large current to flow and often causing fire or equipment damage.

An unintended path of current from a live conductor to earth or to metal enclosures, which can energize equipment and shock anyone who touches it.

An AC supply using three conductors whose voltages peak 120 electrical degrees apart, giving constant power delivery and a rotating field for motors with less conductor material.

The order in which the three phase voltages of a supply reach their maximum; swapping two leads reverses it and reverses the rotation of three-phase motors.

The difference between the synchronous speed of the rotating magnetic field and the actual rotor speed of an induction motor, usually stated as a percentage of synchronous speed.

The amount of light arriving at a surface per unit area, measured in lux; used to check whether a room or task area meets required lighting levels.

The resistance measured between a conductor and ground, or between two conductors, which shows the condition of the insulation; it falls as insulation ages or absorbs moisture.

A portable test instrument that applies a high direct voltage and reads insulation resistance in megohms, used to check wiring and motors before energizing them.

The ratio of the maximum demand of an installation to its total connected load; applied to avoid oversizing service equipment that would never carry every load at once.

A device that transfers energy between two AC circuits through a shared magnetic field, stepping voltage up or down while current changes in the opposite direction.

The product of RMS voltage and RMS current in an AC circuit, measured in volt-amperes; it includes both the real power doing work and the reactive power oscillating in the system.

The national standard enforced in the Philippines for the design, installation, inspection, and maintenance of electrical systems; it sets minimum safety requirements patterned on recognized international practice.

The government official or office responsible for enforcing the Philippine Electrical Code, issuing electrical permits, and approving plans and finished installations.

The circuit conductors between the final overcurrent device protecting the circuit and the outlets or utilization equipment supplied by it.

The circuit conductors between the service equipment, or the source of a separately derived system, and the final branch-circuit overcurrent protective device.

The conductors and equipment that carry power from the utility service point to the building's service equipment, including the service drop or lateral conductors and the meter.

An enclosure with buses and overcurrent devices that divides incoming power into branch circuits or feeders and is installed at one accessible location.

An enclosed channel of metal or nonmetallic material designed to hold and protect wires and cables, such as conduit, tubing, and wireways.

A tubular raceway, metallic or nonmetallic, used to route and protect conductors; code rules limit how full it may be and how sharply it may be bent.

The circuit conductor deliberately connected to earth, usually the neutral, which carries return current during normal operation and is identified by white or gray finish.

The conductor that connects the metal frames and enclosures of equipment to the grounding system, giving fault current a low-impedance path back to the source.

The permanent joining of metal parts so they form a continuous conductive path with enough capacity to carry any likely fault current safely.

A fuse or circuit breaker that automatically opens a circuit when current exceeds its setting, protecting conductors and equipment from overheating and damage.

A switch or other device that can cut off the conductors of a circuit from their source, letting workers safely service equipment.

A device that compares current in the hot and neutral conductors and trips when a small imbalance indicates leakage to ground, protecting people from shock.

A load that is expected to run at maximum current for three hours or longer; conductors and overcurrent devices for it must be sized at 125 percent of the load.

A complete lighting unit made up of one or more lamps plus the parts that hold them, distribute their light, and connect them to the supply.

An area where flammable gases, vapors, dust, or fibers may be present in amounts that could ignite; special equipment and wiring methods are required there.