I have a switch (Double pole / One throw) that controls the ceiling fan and light in my master bathroom (B1). I'm considering to replace it with two single switches, so I don't need to turn the light on if I want just to use a fan, and vice versa - to use a light without fan.

Some notes:

  • When I turn the lights ON, the fan is ON with a delay (approx 1 min). If I turn the lights OFF, the fan is OFF with a delay approx 5 min. That delay is not controlled by that switch (it can't do that by specs).
  • The same fan is also used for the second bathroom (B2). It also has a switch that controls it. However it works differently (less control). If I turn the lights ON only in B2, fan is not activated. If I then turn the lights in B1, it's activated. Next, if I turn the lights OFF in B1 but leave the B2 lights ON, the fan is still working till B2 lights are OFF (+ 5 min delay). So basically B2 switch can run the fan only if it's already activated by B1.

The wiring diagram looks like below:

Cable 1 (two ends, black (C1_1) and red(C1_2))

Cable 2 (one red end C2)

Cable 3 (one red end C3)

The switch has 4 terminals (let me name it T1-T2-T3-T4).


C1_1 --> T1

C1_2 --> T3

T3 --> T4

C2 --> T2

C3 --> T2


1) Is it correct to assume that switch really controls fan/light and can be replaced with two single switches? Or I need to wire more cables?

2) Is it correct to assume that T3 & T4 are for LINE, and T1 & T2 are for LOAD?

3) What is the purpose of C3? Does it have any relations to B2?

  • It is not very clear if you have two bathrooms that each have their own fan of the same model ... or ... if both bathrooms are vented by the same fan unit. – Michael Karas Jun 4 '18 at 7:24
  • @MichaelKaras, both bathrooms are vented by the same unit – Anton Jun 4 '18 at 8:05
  • Is there some sort of controller that goes with this fan? – ThreePhaseEel Jun 4 '18 at 11:47
  • 1
    T1-4 doesn't help us if we don't know which one connects to which when the switch is closed. Also if the switch has any internal bonds, straps or tabs. I tried inferring it but it's too ambiguous. Also I take it you are in North America and failing to mention a clump of white wires in the back of the box? Please elucidate or post photo(s). – Harper - Reinstate Monica Jun 4 '18 at 15:34
  • @Harper, the switch is CLIPSAL 30MD (AU), however the names of T1-T4 may not match the names in specs as it's not clear which one is what. It appears the battery in my meter is dead atm, so can't test it. – Anton Jun 5 '18 at 0:42

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