The Range of TP**-*-* Series Surge Protection Devices are designed to provide protection for sensitive electronic equipment, and are intended to be mounted within a Hazardous Area. 

Within the TP48-*-* Series Surge Protection Devices, three different wiring configurations are available, TP48-2W (2-wire,) TP48-3W (3-wire) and TP48-4W (4-wire). All the TP48-*-* Series units have the same safety input parameters for intrinsic safety purposes. Each unit has two, three or four active connections and an earth connection, but all connections must form part of the same intrinsically safe circuit.

The TP32-*-* Series Surge Protection Devices provides a further configuration which has three active connections and an earth connection but all connections must form part of the same intrinsically safe circuit. The TP32-*-* Series units have the same safety input parameters as the TP48-*-* Series units for intrinsic safety purposes.

The TP**-*-* Series units comprise various combinations which include three-terminal gas discharge tubes, voltage dependant resistors, silicon avalanche diodes, and a diode bridge circuit mounted on a printed circuit board. Each of these assemblies is encapsulated within a tubular metal enclosure, sealed at one end. The open end is provided with a threaded stub intended for screwing into the enclosure wall of other apparatus. The connection wires emerge from the encapsulation at the open end of the threaded stub and are intended to be terminated within the apparatus enclosure. Various different thread forms are available denoted by the suffix N, I or G, to the type number.

See Annex for the range covered and for the Input / Output Parameters, differing Temperature Classifications and Ambient Temperature limits

1)  The apparatus is to be installed such that the flying leads are afforded a degree of protection of at least IP64.

2)  Although all versions of the TP48-*-*, TP32-*-*, TP32-T-* and TP24/7-*-NDI Series Surge Protection Devices will meet the 500V test to the metal case, the electrical circuits within the Surge Protection Devices are not capable of withstanding the 500V test to the Green/Yellow wire for one minute without breakdown. This must be taken into consideration in any installation. 

3)  These devices are not provided with an external connection facility for an earthing or bonding conductor. Adequate earth continuity via the mounting arrangement must be ensured.