240v or low voltage

[boballen]

We have just moved to a 17 year oldhouse with two non working 240v extractor fans in the bathroom (about 3foot from bath). These fans have ducting in place to the room/outside.
I think I cant install a 240 v replacement. If I install a low voltage model where doe the transformer go?
Any suggestions as easy to fit models

 

[Softus]

I think I cant install a 240 v replacement.

Why not?

 

[boballen]

I have since been to shops where it is clearly not the case ...but can I find one to take the originally place==== I thought that the light was connected but it seems not so I will have to use one with its own cord? (unless I want some serious electrics?)

 

[Softus]

Why not just get one with its own humidistat?

There's the other matter of having the means to isolate the fan, but that applies to the old one as well as the new one.

 

[boballen]

yes- I think this means I need a switch outside the bathroom? I guess there is no getting round this- as I would quite like to do the job myself and this would be beyond my skill level.

 

[ban-all-sheds]

What would be beyond your skill level?

 

[Softus]

yes- I think this means I need a switch outside the bathroom? I guess there is no getting round this- as I would quite like to do the job myself and this would be beyond my skill level.

Although you shouldn't take on anything you really believe you can't do, this job is not as hard as you might currently (arf) think - maybe your confidence is just low?

Seriously, if you're merely replacing an existing fan and adding a switch, then this work is not classed as risky or significant enough to be notifiable under the Building Regulations.

Follow, to the letter, the fan manufacturer's intructions, isolate everything you're working on, plan out the work, do it slowly and carefully, never miss out an earth, even temporarily, and test the result with whatever means you have available.

The switch needs to be a double pole type - for your application you can get these both in faceplates and pullcord units.

 

[ban-all-sheds]

Seriously, if you're merely replacing an existing fan and adding a switch, then this work is not classed as risky or significant enough to be notifiable under the Building Regulations.

From Statutory Instrument 2004 No. 3210 The Building (Amendment) (No.3) Regulations 2004:

"special location" means a location within the limits of the relevant zones specified for a bath, a shower, a swimming or paddling pool or a hot air sauna in the Wiring Regulations, sixteenth edition, published by the Institution of Electrical Engineers and the British Standards Institution as BS 7671: 2001 and incorporating amendments 1 and 2.

 

[Softus]

Seriously, if you're merely replacing an existing fan and adding a switch, then this work is not classed as risky or significant enough to be notifiable under the Building Regulations.

From Statutory Instrument 2004 No. 3210 The Building (Amendment) (No.3) Regulations 2004:

"special location" means a location within the limits of the relevant zones specified for a bath, a shower, a swimming or paddling pool or a hot air sauna in the Wiring Regulations, sixteenth edition, published by the Institution of Electrical Engineers and the British Standards Institution as BS 7671: 2001 and incorporating amendments 1 and 2.

Right - I can see that the way I've written this is too glib.

I was interpreting the following text from the ODPM web site:

You do not need to tell your local authority's Building Control Department about:

* repairs, replacements and maintenance work; or
* extra power points or lighting points or other alterations to existing circuits (except in a kitchen or bathroom, or outdoors).

The replacement of the fan falls under the first bullet point. The addition of a switch is not an alteration to a circuit.

There is room for doubt, so, as the ODPM web site also says: if you are not sure about this, or you have any questions, ask your local authority's Building Control Department.

 

[boballen]

thanks for all the advice!
Decided to contact building control:
If I as owner rI elace the unit then I dont need to sit external switch I just replace - I guess but didnt ask that if a qualified electrician relaces it then they would need to.
The advice I had from them was to fit one with either a humidity contol or ir sensor as the unit does not appear to have been conneected to pull light switch.
What is the yellow cable? (not an earth cable as there is one of those)

 

[Softus]

Please test to confirm this, but the yellow cable is probably a switched live.

For example, the borken fan might have been one that comes on when the light is switched on and continues running for a pre-determined timed period when the light is switched off. Such fans need need two live supplies to achieve this.

The last humidistat fan I fitted had a termination for a switched live, but of course it didn't do anything unside the fan unit, because it operated according the ambient humidity.

Although the ODPM guidance discriminates between you and a contractor doing the work, I'm slightly queasy about the way the BC appear to have discriminated. If the installation is not to standard then they should advise you either to fit a switch or to use a contractor, not to leave out a switch because it's your house!

Anyway, I believe that in replacing a broken fan with a working one then you are not making anything less safe.

 

[boballen]

Ahh - OK Think I have found the answer to the home relacement of the said fan.

Blue Red yellow and earth (copper)

Fan has two connections L (Live) and N(Neutral) it is not necessary to earth - it says in instructions

I have tested the three cables with multimeter
With Pull Switch on:
between Blue and red 230v
between blue and yellow 230 v

With pull switch off
between blue and red 240v
between blue and yellow Ov

So do I
put yellow wire to Live and blue to neutral
and then insululate (make safe) the red
and just forget the earth cable

 

[ban-all-sheds]

I was interpreting the following text from the ODPM web site:

You do not need to tell your local authority's Building Control Department about:

* repairs, replacements and maintenance work; or
* extra power points or lighting points or other alterations to existing circuits (except in a kitchen or bathroom, or outdoors).

The replacement of the fan falls under the first bullet point. The addition of a switch is not an alteration to a circuit.

I'm afraid that text is wrong.

And if you take take the trouble to read the actual law, it will be obvious that it is wrong.

But don't tell them - it's handy for there to be a Govt website that says that, in case you want to interpret a complete rewire as "repairs, replacements and maintenance work"

 

[ban-all-sheds]

put yellow wire to Live and blue to neutral
and then insululate (make safe) the red
and just forget the earth cable

Yup.

Make the earth safe as well - use a 2-way bit of choc-block inside a choc-box for the permanent live and the earth.

And put red sleeving on the yellow.

 

[Softus]

Ahh - OK Think I have found the answer to the home relacement of the said fan.

Blue Red yellow and earth (copper)

They're all copper! Do you mean that's not insulated? If so, then I recommend that you sleeve the bare copper.

I have tested the three cables with multimeter
With Pull Switch on:
between Blue and red 230v
between blue and yellow 230 v

With pull switch off
between blue and red 240v
between blue and yellow Ov

Right - that confirms that the yellow is the switched live. (Not sure where you got the extra 10V from though).

So do I
put yellow wire to Live and blue to neutral
and then insululate (make safe) the red

Not for a humidifan - instead, connect red to Live and insulate the yellow.

and just forget the earth cable

NO!

The earth may not connect to the fan, but it also acts to protect the run of cable to the fan.