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How can a single pole, 3 position selector switch be created from standard 22mm Harmony parts?

This FAQ is intended to clarify what parts are required to create a single pole, 3 position selector switch (1 circuit selected or 'made' in each of the 3 positions) as detailed below;

The parts listed are based on the metal bodied ZB4B 22mm range but could also apply to the plastic ZB5A equivalent parts.

The 3 position switch* has 2 plungers. In the left position the left plunger operates a contact block in the left and centre. In the right position the right plunger operates a contact block in the right and centre.

KEY; Black square = contact closed.  White square = contact open.

Thus to obtain 3 separate circuits, one of which will active (logic state 1) in each of the 3 positions, then 3 contact blocks will be required as follows;

Left position; ZBE101 (N/O) Contact only closes (makes circuit) in left position.

Centre position; ZBE102 (N/C) Contact only closed (makes circuit) in centre position, when switched to left or right the contact is opened.

Right position; ZBE101 (N/O) Contact only closes (makes circuit) in right position.

The above can be specified as a ZB4BD3 (3 position head) + ZB4BZ103 (body with 2 N/O contacts) + ZBE102 (N/C contact block)

*Important note; This information is based on the newer (as featured in current catalogue) design of 3 position selector switches (e.g ZB4BD3) that have a revised design of plunger.

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