Able with cable | Archive Titles

Figure 2. Wiring type	Technique	Advantages/disadvantages

Double pole 4 wire	2 closed loops (circuit conductors) at different polarities. Loops provide supervision for 'detection' and 'tamper' by responding to a cut cable at all material times (24 hrs). Proposed for EN Grade 2 systems.	Traditional and easily understood. All systems using this configuration can be easily retrofitted.Individual circuits are used but this reflects in greater cabling run lengths.
End of line (EOL) 2 wire	An EOL device used for the detection loop at the 'far'end of the circuit. The control equipment analyses the impedance.	Understandable and a progression on double pole.Manufacturers use different EOL values. Can not be retrofitted without amending the wiring at the final device.
Dual operation Fully supervised loop (FSL) or EOL 2 wire	Resistors are fitted in parallel in the detection device across the contacts. May also use series resistors plus an EOL. Proposed for EN Grade 2 systems which require remote maintenance to be carried out.	Provides full supervision with a reduction in cabling. Not easily retrofitted. Resistors are supplied by the manufacturer to suit the equipment type.
Triple resistors FSL 2 wire	Use variant value resistors for alarm contact, fault contact and EOL. Proposed new generation type for EN Grade 3 systems.	Provides full supervision and fault contact anti-masking with circuit analysis of all wiring states. Not easily retrofitted.
Multiplex. Data bus. Addressable	Use main data highways, branches or node type networks (point in a circuit at which the conductors join to form a junction).	No requirement to wire each device as a 'home run' back to the main control point.Equipment differs enormously in terms of parameters and system configurations.