Current flow direction -
Direct current (DC) -
Electrical system -
Ground conductor -
Ground fault – This happens when an ungrounded conductor (line wire) comes in contact with anything that is grounded, (i.e. motor winding touching case, or line 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.