Correcting installation/wiring of in duct extractor

[bracknelldiy]

House moved into has an Addvent AVX 100 IDT timer in duct extractor fan serving the bathroom. Fan is located in loft space. However it does not 'overrun' the timer switch; it has only been wired up to feed from light switch.

I don't have a manual/wiring diagram for it and can't find one on maufacturer's website. I suspect wiring to permanent live is straightforward and probably common across most fans. Fan has a 3 terminal block on the board. If terminal 1 is the one taking the live from the switch, there is a connecting wire from terminal 1 to terminal 2.

Should the permanent live be taken into terminal 2? Should this replace the bridging connection from terminal 1 to terminal 2 (I.e. remove the briding wire between the terminals?

 

[electronicsuk]

You are right in your assumption that the two linked terminals must be the L and SL supply. If there are no other indications or marking on the terminals then take a 50/50 punt and wire up the switched live to one terminal and the permanent live to the other. If it doesn't work, swap them around. It won't damage the fan.

 

[bracknelldiy]

many thanks, and blimey that was a fast response.

This is probably a daft question if I thought about it. Assuming I take a permanent live feed from another source/circuit connection box. Do I just connect the live up, or should I also be connecting the neutral as well (an potentially the earth's).

I guess I ought to know the answer to that.....

 

[Taylortwocities]

You can take the live from another point but

1. It must be from the same lighting circuit or your RCD will trip and you'll have no electricity.
2. If you run another cable for the live (from another point) you must connect the earth (cpc) conductor otherwise there is no protection for the cable. The neutral is not needed. It is already at the fan.
3. Do you have a fan isolator switch?. If so the live should route through that switch so that all connections to the fan are isolated when the switch is turned off.

 

[bracknelldiy]

many thanks, very helpful.

Fan isolator switch: good point, I need to do some tracing back (if there is then it is in the roof space, not downstairs.

Point re. same lighting circuit. OK, thanks. Hadn't considered that but makes sense (move from 1 bed flat to 4 bed house = not taking into account potential for multiple lighting circuits).

 

[Taylortwocities]

There probably is only one circuit for upstairs, but the bathroom may be separate due to new requirements for RCDs in bathroom circuits.

 

[bracknelldiy]

Given the way this place is wired....probably not And don't even start to mention the heating system....

So: yes there is an isolator switch, in roof space. Existing feed from bathroom light switch is routed via the isolator (based on obvious test....).

however, access to back of isolator box is restricted/zero.

Given that fan is an in-duct fan located in the roof space, what is the practical 'risk' being taken if I was to bypass the isolator switch w.r.t. to putting in a permanent live feed ?

(And I'm not quite sure, based on cursory exam, how I could take a permanent live feed into the switch without then making the circuit up from the bathroom light switch live when it shouldn't be.....). Perhaps that means it has the wrong isolator switch type?? Or I'm being dopey.

 

[bernardgreen]

Given that fan is an in-duct fan located in the roof space, what is the practical 'risk' being taken if I was to bypass the isolator switch w.r.t. to putting in a permanent live feed

You are cleaning the dust out of the fan and you wife comes up with a cup of tea for you and seeing the bathroom is dark she helpfully turns the light on.