How to Wire a Key Switch

Key switch for tubular motor

Following on from our post about hot wiring a key switch, in which we showed that the ones we use don't break open when you apply a hammer to them, we would like now to show how to wire them up.

Obviously, there is a logic behind this, but if you don't do a few of them, the logic escapes us.


Basically, connect the Earth Wire of the motor to the Earth wire from the fuse spur. In addition, you should earth the switch itself. The key switch should have a terminal to join all three.

Next, connect the Blue fuse spur wire to the motor Blue wire. The motor Blue wire serves as the common, through which the 230V passes when the switch completes the circuit.

Finally, the fuse spur Brown wire is connected to the switch itself, to BOTH key switch buttons. When the button is pressed, the current will flow into either the Brown or Black motor wire, and provide direction to the motor turning. Therefore, fit the motor Brown and Black to the key switch buttons, one in each.

Wire a key switch
Wire a key switch

Key switch wiring schematic

Or, if you prefer, look at it like this.

Once you have worked out how to wire it, you might find it equally problematic to fit all the wires into the key switch enclosure. You need a hole in the enclosure big enough for two flex cables.. and, you will have to work out how to fit it so that it has a pleasing position, with some trunking or conduit. Often, you need to put it on the outside of a building, feed the flex cables through to the switch..

I would have a spare switch handy since you may drill the hole into it in the wrong position. You may, for instance, block the action of the key barrel with your flex. I have indicated the ideal positions for drilling into the enclosure.

Don't forget to fix it parallel to surrounding objects, or it will look skewed. And, you may need to open the holes for your fixings to go through in order to give some tolerance around positioning the switch to the wall in a straight aspect.

Stuffing everything inside the switch enclosure takes practice, and it is better to stow the lot of it elsewhere if you can.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.