ACCESS CONTROL: means of influencing and regulating flow of persons through a door, entry and/or exit alarm

ADJUSTABLE: ability to change or alter time delay or other parameter by means of adjustment, such as a potentiometer, resistor, or switch

AIRTRAPS: see interlock

ALTERNATING CURRENT (AC): electric current that reverses its direction regularly and continually; the voltage alternates its polarity and direction of current flow negative to positive

AMERICAN SOCIETY FOR TESTING MATERIALS (ASTM): organization that tests materials and attempts to set standards on various materials for industry

AMERICAN WIRE GAUGE (AWG): standard system in the United States for designating wire size (diameter of metal)

AMPERE (amp): unit of measurement for the rate of electrical current flow; one ampere is the current flowing thorough one ohm of resistance at one volt potential

AMPERE/HOUR (AH): measurement of a battery’s capacity; one ampere of current flowing for one hour equals one ampere/hour

ANNUNCIATOR: audible and/or visual signaling device

ARC: electrical current through air or across the surface of an insulator associated with high voltage; usually occurs when a contact is opened, de-energizing an inductive load; arcing of a contact will limit its life

AUTOMATIC SURGE: device incorporated into a stainless steel perimeter

AUTHORIZED RELEASE DEVICE: device that allows authorized persons to enter or exit monitored and controlled openings without triggering an alarm; the authorized passage release may be a keyed switch, a card reader, a digital code reader

BATHER LOAD: number of people in a pool or spa at a particular time or during a specific period of time

BATTERY STANDBY: means of automatically switching over to stored battery power during local primary power failure

BALANCED WATER: correct ratio of mineral content and pH level that prevents the water from being corrosive or scale forming

BREAK: open an electrical circuit

BREAKDOWN VOLTAGE: voltage at which insulation between two conductors is destroyed

BROWNOUT: low line voltage that can cause misoperation of and possible damage to equipment

CHECK VALVE: mechanical device in a pipe that permits the flow of water or air in one direction only

CIRCUIT: path through which electrical energy flows

CIRCUIT BREAKER: switch, which allows manual override of an electrical circuit. It also automatically breaks the circuit when current fluctuations are detected

CIRCUIT, CLOSED: (1) electrical circuit in which current normally flows until interrupted by the opening of a switch or a switch-type electronic component (2) circuit or switch in which the contacts are closed during normal operation

CIRCUIT, OPEN: (l) electrical circuit in which current does not flow until permitted by the closing of a switch or a switch-type electronic component (2) circuit or switch in which the contacts are open during normal operation

CLOSURE: point at which two contacts meet to complete a circuit

CODE: see national electrical code

COIL, ELECTRIC: successive turns of insulated wire that create a magnetic field when an electric current is passed through them

CONDUCTOR: material with the ability to carry electric current; the term is also used for an electric wire

CONDUIT: tube or trough for protecting electrical wires or cables

CONNECTOR: any device used to provide rapid connect/disconnect service for electrical cable and wire terminations

CONTACTS: electrically conductive points, or sets of points, used to make or break an electrical circuit mechanically

CONTINUITY: state of being complete and uninterrupted, like a normally closed circuit

CONTINUITY CHECK: test performed on a length of wire or cable to determine whether the electrical current flows continuously throughout the length

CONTINUOUS DUTY: device or control that can operate continuously with no off or rest periods

CONTINUOUS DUTY LOCKING UNIT: electric lock equipped with a heavy-duty solenoid that can be energized indefinitely

CURRENT: flow of electrons through a conductor; current is measured in amperes

DECIBEL (dB): increment of measurement used to compare measured levels of sound energy (intensity) to the apparent level detected by the human ear; expressed as a logarithmic ratio (sound that has 10 times the energy of another sound is said to be 10 decibels louder; 100 times the energy is 20 decibels louder; 1,000 times the energy is 30 decibels louder; and so on); decibel levels are correctly expressed as the number of decibels at a measured distance from source of sound (for example,125 dB at 10 feet)

DE-ENERGIZE: to remove power

DELAY ON BREAK: mode of operation relative to timing devices; delay begins when the initiate switch is opened (delay on break of initiate switch) 

DELAY ON ENERGIZATION: : (1) mode of operation relative to timing devices; delay begins when initiate switch is closed or on application of power to input (2) also called delay on make

DELAY ON MAKE: see delay on energization

DIRECT CURRENT (DC): electrical current that travels in only one direction and has negative (-) and positive (+) polarity; it may or may not have an AC ripple component; DC sources that are unfiltered should be referred to as full-save or half-wave rectified AC

DOOR STATUS SWITCH (DSS): used to monitor whether a door is in an opened or closed position

DOUBLE POLE, DOUBLE THROW (DPDT): (1) switch or relay output contact form (2 form C) in which two separate switches are operating simultaneously, each with a normally open and normally closed contact and a common connection (2) used to make and break two separate circuits

DRY CONTACT: metallic points making (shorting) or breaking (opening) a circuit; the switched circuit must have its own source of power and is merely routed through the dry contacts

DYNAMIC HEAD: sum of all the resistance in a complete system when in operation; the principle factors of “head” are vertical distances and resistance due to friction of the flow against the walls of the pipe or vessel; friction head is the head due to friction only