General-Use Switch - see definition for Switch.

Gradient, Voltage - The voltage drop, or electrical difference, between two given points.

Ground - A connection to earth obtained by a grounding electrode.

Ground Counterpoise - a conductor installed over (airport) lighting cables for the purpose of interconnecting the system ground electrodes and providing lightning protection for the cables.

Ground Fault - Any undesired current path from a point of differing potential to ground.

Ground Fault Circuit Interrupter - A device whose function is to interrupt, within a predetermined time, the electrical circuit to the load when a current to ground exceeds some predetermined value that is less than that required to operate the overcurrent protective device of the supply circuit.

Class A Ground Fault Circuit Interrupter (GFCI) - is a protective device that will interrupt the circuit to the load when the ground fault current is 6 mA or more but not when the ground fault current is 4 mA or less (there will be a less then 10% current limit variation when the ambient air temperature is less than –5 °C or more than 40 °C) in a time

• (a) not greater than that given by the equation T = (20 / I)^1.63, where
  T is in seconds; and
  I is the ground fault current in rms milliamperes for fault currents between 4 mA and 260 mA; and
• (b) not greater than 25 ms for ground fault currents over 260 mA.

In addition, a Class A GFCI is to be capable of interrupting the circuit to the load, in keeping with the above requirements if the identified circuit conductor (neutral) becomes inadvertently grounded between the interrupter and the load. The prime function of a Class A GFCI is to provide protection against hazardous electric shocks from leakage current flowing to ground from defective circuits or equipment. It does not provide protection against shock if a person makes contact with two of the circuit conductors on the load side of the GFCI.
Class A GFCIs are marked “GROUND FAULT CIRCUIT INTERRUPTER CLASS A” or with an  abbreviated form such as “GFCI CL A”, “GFCI A”, or “CL A” where the area available for marking makes the complete text impracticable.

Grounding - A permanent and continuous conductive path to the earth with sufficient ampacity to carry any fault current liable to be imposed on it, and of a sufficiently low impedance to limit the voltage rise above ground and to facilitate the operation of the protective devices in the circuit.

Grounding Conductor - The conductor used to connect the service equipment or system to the grounding electrode.

Grounding Electrode - A buried metal water-piping system, or metal object or device buried in, or driven into, the ground so as to make intimate contact therewith, to which a grounding conductor is electrically and mechanically connected.

Grounded - Connected effectually with the general mass of the earth through a grounding path of sufficiently low impedance and having an ampacity sufficient at all times, under the most severe conditions which are liable to arise in practice, to prevent any current in the grounding conductor from causing a harmful voltage to exist:

• Between the grounding conductors and neighbouring exposed conducting surfaces which are in good contact with the earth; or
• Between the grounding conductors and neighbouring surfaces of the earth itself.

Grounding System - All conductors, clamps, ground clips, ground plates or pipes, and ground electrodes by means of which the electrical installation is grounded.

Guarded - Means covered, shielded, fenced, enclosed, or otherwise protected by means of suitable covers or casings, barriers, rails or screens, or mats or platforms to remove the liability of dangerous contact or approach by persons or objects.