I am fitting a combination of fan run-on timer / fan speed control and, um, a fan. The run-on timer will be first in the chain (the trigger terminal will be connected to a light switch), then the switched output connected to the motor speed control and that on to the fan. The run-on timer installation diagram and text indicate a double pole isolation switch before the timer, such that it would isolate all the components. However, I am assuming the isolation switch is only required to isolate the fan itself, so it could be put the other side of the run- on timer, or even between the speed control and the fan. (The speed control includes an "off" switch, but that will only be single pole). Am I correct that the isolator can go just before the fan ? Cheers, Simon.
fan / time delay isolation switch
Apr 01, 2011
5 Replies
If your isolator switches all the lives and the neutral then no problem.
Yes, you get a 3-pole isolator for live, switched live, and neutral. Eg
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The timer is a separate unit and the fan only has live and neutral. In this case, presumably the point of the isolator is to isolate the fan, so I could just use a 2 pole isolator. Simon.
I know I need an isoator for the fan (servicing of motors etc.), but why do I need an isolator for the timer ? It will be connected to the lighting circuit and fitted in a normal back box. If servicing was required, the item would be removed from the back box and the wires disconnected. Simon.
I would not bother with an isolator for the timer.
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