Gauge - A term for specifying the thickness (diameter) of cables. Thicker cables have a lower number in the American Wire Gauge (AWG) scale.

GCAC (Generic Connection Admission Control) - This is a process to determine if a link has potentially enough resources to support a connection.

GCRA (Generic Cell Rate Algorithm) - An algorithm which is employed in traffic policing and is part of the user/network service contract. The GCRA is a scheduling algorithm which ensures that cells are marked as conforming when they arrive when expected or later than expected and non-conforming when they arrive sooner than expected.

Generator - A machine which converts mechanical energy such as the power from a piston engine into electrical energy.

GFC (Generic Flow Control) - The first four bits of the first byte in an ATM cell header. Used to control the flow of traffic across the User-to-Network Interface (UNI), and thus into the network. Exact mechanisms for flow control are still under investigation and no explicit definition for this field exists at this time. (This field is used only at the UNI; for NNI-NNI use (between network nodes), these four bits provide additional network address capacity, and are appended to the VPI field.)

Gigahertz - A measurement of the frequency of a signal equivalent to one billion cycles per second, or one thousand million cycles per second.

GIO - A proprietary bus architecture used in certain Silicon Graphics, Inc. workstations.

Ground - An intentional or accidental connection between an electric circuit or its housing and the ground (earth).

Grounded Neutral - A neutral conductor that is intentionally connected to ground.

Grounded Output - With respect to alarming, refers to an alarm output which is mutually grounded at the originating point of the alarm occurrence (the converse of loop closure alarms).

Ground Fault Current - A fault current which flows to ground.

Grounding Device - Impedance inserted in a grounding circuit which limits ground fault currents.

Ground Return - (1) Conductor which drains current to ground; and (2) conductor used as one common shared path for several circuits back to the grounded side of the main storage battery.

Ground Wire - Copper conductor used to extend a good low-resistance earth to protective devices in an office.

GSM (Group Special Mobile) - The Pan-European digital cellular system standard.

Gutter Tap - A compression tap insulated by tape and left in a wiring gutter.