Current flow direction -
Direct current (DC) -
Electrical system -
Ground conductor -
Ground fault – This happens when an ungrounded conductor (120 V wire) comes in contact with anything that is grounded, (i.e. motor winding touching case, or 120 V wire of appliance touching the metal frame.)
Hot conductor – The ungrounded conductor. This is the conductor that has voltage. In a household, the wire color is black or red.
Kilowatt Hour (kWh) -
Neutral Conductor -
NM Cable -
Nominal voltage -
Higher voltage ratings of 125, 130, 230, and 250 volts are for switches, receptacles, bulbs, and certain loads. These ratings indicate the upper limit of voltage for a device or load to operate properly under normal conditions.
Lower voltage ratings of 110 , 115, and 220 volts are for loads (appliances, motors, etc). These ratings indicate the lower limit of voltage for proper operation under normal conditions.
Open circuit -
Overload* – Operation of equipment in excess of normal, full-
Potential difference -
Qualified person* -
Voltage (Nominal) -
Voltage Drop -
(* Indicates NEC 2014 Article 100 Definitions)
Arc Fault -
Arc fault circuit interrupter (AFCI) – A circuit breaker that will also trip when it detects an abnormal arc.
Arc flash -
Alternating current (AC) – Current that travels in both directions. Residential and commercial power use AC.
Circuit breaker* -
Conductor – Materials that allow the flow of electrons easily, including silver, copper, gold, and aluminum. Electrical wires are mostly made of copper, some are made of aluminum.