I'm considering retrofitting skylight motors but would like to know if I can use standard home switches to control it. I have not found examples of up, down and open switches (is this 3 pole, normally open?). I imagine this should be similar for blinds or any motor that steps in two directions (but not just fully open or fully closed like a garage door).

The skylight manual contains this diagram, first below.

The second I simplified because I don't understand the need for a double-pole, double throw where the Neutral disconnects when untouched. Any ideas why they would want that?

Finally the third diagram shows my idea to use two momentary switches which I believe should work. However would anyone be able to speculate if the motor is likely to have protection against both open and closed being pressed simultaneously? Am I overlooking anything else?

wiring diagram

Update The winning solution is: https://electronics.stackexchange.com/a/340685/169328

The local supplier of one brand, Topp, that operates at mains voltage supplied the following diagram with matches second circuit diagram 2(b).

Switch Wiring Diagram for Topp C20 actuator

This uses two common momentary switches. Note how 2 feeds into C of the second switch.

  • \$\begingroup\$ Safety possibly. Break-before-make is another possible reason, but not sure in this case. Having one switch instead of two means you can never accidentally close both at once. \$\endgroup\$ Nov 19, 2017 at 10:41
  • 1
    \$\begingroup\$ Double pole switching is a safety issue, legally required in some (230V) countries. It keeps the equipment safe even if L and N are swapped due to a wiring error, as sometimes happens. (However fuses must be single pole, only on Live, since the 1930s, as having a Neutral fuse failing would be dangerous). This is one of those "find the right part, don't bodge another solution" situations. \$\endgroup\$
    – user16324
    Nov 19, 2017 at 15:09
  • \$\begingroup\$ Ah yes safer if L and N are swapped must be why. I actually have two skylights and need both controlled from one standard wall plate. Unfortunately the "right part" doesn't seem to exist from standard domestic suppliers for AU/NZ. The electrician and will know the difference between live and neutral \$\endgroup\$
    – KCD
    Nov 19, 2017 at 18:33
  • \$\begingroup\$ In Europe it should be possible to get a 2 gang version of this S50 windowopeners.co.uk/products/controls/switches/… \$\endgroup\$
    – KCD
    Nov 19, 2017 at 19:32

2 Answers 2



simulate this circuit – Schematic created using CircuitLab

Figure 1. (a) Probable wiring scheme. (b) Typical limit-switch wiring.

You are probably correct in thinking that the neutral need not be switched. The manufacturer may have had some reason to prefer that the motor is fully isolated though so you should check the motor units to see.


simulate this circuit

Figure 2. Possible solutions using standard domestic single-pole, 2-way switches. Both circuits prevent attempting to run both motor coils simultaneously.

You should have no difficulty in obtaining a changeover switches and wiring them as shown in Figure 2.


You could do it with two distinct switches but you need to ensure that both cannot be switched at once, I would presume that there is nothing inside the motor to avoid this as they state the need for the DPDT. I would suggest this is the best option.

Does this have some kind of limit switch to avoid pressing the motor when its finished closing or opening?

You COULD use a single pole double throw (SPDT) standard switch (non momentary - SW1) followed by a SPST momentary (SW2) so you could switch SW1 down for close, and up for open (for example), and hold the momentary SW2 while you do the opening or closing. That way you cannot be applying both at same time. (you could also use a DPDT latching for SW1, these are easier to find then SPDT here)

![enter image description here

If you can only find momentary SPST, you could add contingency by using a third switch, and having to hold 2 to operate, so one for each pole (up or down) and one for the 'go'.

Hope I have given you some ideas anyway :-)


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