I was looking at one of these to upgrade an existing fan. It is installed in conjunction with a double pole fused spur isolator. The timer control takes a permanent live and a switched live. So if the double pole switch is off and the bathroom light is still on then the fan timer unit unit still has the switch wire live. Does this appear a bit misleading? A triple pole switch would appear better but would not be able to be fused down to 1 amp and the instructions specify a double pole fused spur.
Any opinions on these out there?
This has been a favourite among PIR inspectors for a couple of years...
One way is to fuse down the entire lighting circuit by putting it on a 3A MCB. Or a provide a separate 3A MCB lighting final circuit to supply just the bathroom .
Another method uses the existing pull-cord switch to control the light and fits an 3A FCU and 2nd pull-cord switch to control the fan. Take T+E from the lighting point direct to the 3A FCU. This then feeds the Live to the 2nd pull-cord switch. This provides all requirements of the fan and timer, Permanent Live and Neutral from the FCU and Switched Live from the pull-cord switch.
Advantages of this method are:
1) The customer use the bathroom light during the night without the fan whizzing for minutes after vacating the bathroom
2) It meets the Part P requirements and manufacturers recommendations.
3) The fan can be worked on with the bathroom light still on as fan can be isolated independently.
4) The fitting of a pull-cord switch in series with the 3A FCU removes the need for 3 pole isolator.
A third method, the result of a question and answer session at an ECA/ELECSA forum that I attended, where the general consensus of opinion was to use a 3 pole fan isolator and omit the 3A fuse(s) and note the departure from the manufacturers instructions on the EIC.
A fourth method, some manufacturers instructions say that the 3A fuse(s) may be omitted if the supplies are derived from a 6A MCB via a 3 pole fan isolator.
A fifth method, recently I started using fans from National Ventilation which don't mention the use of a 3A fuse in the manufacturers instructions.
National Ventilation
I've used all these methods at various times, I hope this helps mate.
