Wiring an extractor fan directly

[Dysdf]

Dear All,

We are planing to install an Xpelair C100HT Humidistat extractor fan in the bathroom and wanted to connect it directly rather than using switched live from the lighting circuit. But we are planning to take feeds (L and N) from the lighting circuit (ceiling rose). The reason is we need to use the shower/bathroom during the day times and do not need to have lights on. Xpelair's proposed installation is also similar to this. I have attached a link to the proposed wiring diagram. We are not going to add the optional lamp in the circuit, but planning to use a FCU (DP) with a 3A fuse as the fan isolator.

We are very grateful for your views and advise on this. Many thanks, DYSDF

Link:
http://www.fastlec-pdf.com/Xpelair/contour-maintenance-instructions.pdf

 

[JohnW2]

We are planing to install an Xpelair C100HT Humidistat extractor fan in the bathroom and wanted to connect it directly rather than using switched live from the lighting circuit. But we are planning to take feeds (L and N) from the lighting circuit (ceiling rose). The reason is we need to use the shower/bathroom during the day times and do not need to have lights on. Xpelair's proposed installation is also similar to this. I have attached a link to the proposed wiring diagram. We are not going to add the optional lamp in the circuit, but planning to use a FCU (DP) with a 3A fuse as the fan isolator. We are very grateful for your views and advise on this.

That all sounds fine. What, if anything, are your concerns? The DP FCU obviously needs to be located somewhere sensible and compliant with regs. If you did not intend to also use a 'on/off switch' (i.e. only use the FCU to switch it on/off), per their diagram, then you would need to join the L and T terminals of the fan with a little bit of wire.

Kind Regards, John

 

[Dysdf]

Dear JohnW2,
Many thanks for your quick response and many thanks for comments. We are not expecting to use the switched FCU as the 'ON/OFF' switch (only to use this as the isolator switch). We are purely depending on the Humidistat function to switch it on (and then the timer to take over), But as you have suggested, we are going to use a SP Pull Cord switch to connect Live to 'T' as in the diagram, this will cover the point you have mentioned. Our concerns were the regulation requirements. Thanks again for your views and the comments on this. With kind regards, DYSDF

 

[PrenticeBoyofDerry]

So you intend to use a DP FCU (3A) as isolation and a DP pull cord switch to operate the overrun (without light).
There are no regulations saying you have to link in to light, what you must do is insure what you do is safe.
So permitted safe zoning of cable (or mechanical protection to cable).
Bathroom equipment must be suitable for it location and be correctly IP rated for the zone it is installed, 30mA RCD protection required in bathroom.
Inspection and Testing of work as recommended in BS7671, either a minor works or electrical installation certificate issued on commissioning and if work is done within the bath room zones, application/notification to building controls.

 

[JohnW2]

Dear JohnW2, Many thanks for your quick response and many thanks for comments. We are not expecting to use the switched FCU as the 'ON/OFF' switch (only to use this as the isolator switch). We are purely depending on the Humidistat function to switch it on (and then the timer to take over), But as you have suggested, we are going to use a SP Pull Cord switch to connect Live to 'T' as in the diagram, this will cover the point you have mentioned. Our concerns were the regulation requirements.

Fair enough. Do you envisage ever switching it off with the pull switch, or are you going to leave it 'on' virtually all of the time, so that the humidistat will always switch it on when humidity rises high enough (after which, as you say, timer takes over once humidity has fallen below the threshold)? If the former (virtually always leave it switched on), then, as I said before, you could dispense with the pull switch and simply put a permanent link between the L and T terminals of the fan (you'd always have the FCU available to switch it completely off, if you ever wanted to). However, if you do want the pull switch functionality, then what you propose would be fine. I can't think of any 'regulation issues' with either of these approaches.

Kind Regards, John

 

[Dysdf]

Dear JohnW and PrenticeBoyofDerry,

Many thanks for your quick replies and for comments.

Regarding the point mentioned by PrenticeBoyofDerry, we will have 30 mA RCD protection, will add this to the whole lighting circuit.

Regarding the point mentioned by JohnW, I totaly agree with you, I will end up leaving the pull switch on, leaving humidistat to take control ( switch on when the humidity rises). Therefore as you suggested having a permanant link (between the L and T terminals of the fan) would be the best option for me.

Thanks again, kind regards, DYSDF