RS PRO Contact Block for Use with ADA16E Series, 125 V ac, 250 V ac, 1CO

Sub-assembled, modular construction, alternate action, Key Switches designed to fit industry standard 16mm diameter cut-outs in panels with a thickness between 0.5 and 5mm. The Key operators can be fitted to any of the Contact Blocks allowing various combinations of switching (for Contact Blocks see stock numbers 745-2427, 745-2423 and 745-2420). Each Contact Block has 2.8x0.5mm universal terminals that allow either direct soldering or plug in receptacles. Installation and assembly is quick and easy, once fully fitted each Key Switch has a waterproof panel sealing to IP65.
These two position Key Switches feature single entry keys (can only be inserted into the lock one way up), 90 degree indexing and same (common) key profile. Stock number 745-2433 key is trapped (non-removable) at 90º while stock number 745-2439 is non-trapping (key removable) at 0º and 90º.
A square bezel converter (stock number 745-2552) can be used to change the Key Switches into flush countersunk mounted versions. Each converter is supplied with a fixing bow, gasket and a black plastic flush mounting bezel.
Other switches in the ADA16 series include Rotary Selector switch, Buzzer, Emergency Stop (E stop), Pilot Light Indicators and sub-assembled, modular construction, illuminated or non illuminated Push Button switches, to view a portion of these see stock numbers 745-2436, 745-2445, 745-2442, 745-2486 and 745-2449 respectively.

Waterproof rated to IP65
16mm Ø panel cut out
Two versions available, trapping (key removable in one position) or non-trapping (key removable in both positions)
Square 18x18mm operator fascia with alternate switching
VDE rated to 5A 250Vac (8A 125Vac)
Silver contacts
Insulation resistance >50MΩ
UL94-V0 flammability rated
-25 to +55°C operating temperature range

Supplied with 2 keys, spare keys currently not available.
Contact blocks must be ordered separately, see stock numbers 745-2427, 745-2423 and 745-2420.
For suitable contact block mating connectors see stock number 680-2158 typically.

UL, cUL, ENEC, VDE

Need a contact unit to use as part of a modular switch? Try this one from RS PRO to turn your equipment on and off. You can use this unit together with a separate actuator to configure various combinations of switch setups.


The unit is versatile and quick to install as it has universal terminals that can be plugged in or soldered. The contacts are made of silver, which offers excellent conductivity in addition to wear and oxidation resistance. This means the unit is built to last and will deliver reliable performance over its lifespan.


A broad operating temperature range of -25°C to +55°C makes this component suitable for a variety of demanding environments, such as hot warehouses or cold storage units. You can use it for push button switches in lighting and industrial machinery applications.