Swapping current 12v bathroom fan with 230v

[eitherxor]

I want to change my current bathroom fan with a new one that I purchased.

- The current fan is 12v, whereas the new fan is 230v.
- I have 2 wires, live and neutral
- Those 2 wires are connected to a S.E.L.V extension before being wired into the current fan
- New fan takes 2 wires
- I do have an isolator switch just outside the bathroom

What do I need to do to run the 230v fan on this line?

The new fan is nothing fancy, basic on/off, no sensors, just looks a bit better and has a smaller profile than my current one.

Thank you

 

[Taylortwocities]

Somewhere you have a transformer. It is probably the SELV device you refer to?
This converts the mains voltage to 12volts of the existing fan. It probably also contains a timer.

You’ll need to remove this transformer as the new fan is a mains one!


Then you’ll need to look at the wiring that runs from the transformer to thd fan and decide if it is suitable for mains voltages and if it has a CPC (earth) conductor.

If that’s all to code then you need to replace the transformer with a suitable junction box.

EDIT. also you probably won’t need the pull switch on the new fan. I expect the fan will come on and off with the light. I hope that’s what you want?

 

[eitherxor]

Somewhere you have a transformer. It is probably the SELV device you refer to?
This converts the mains voltage to 12volts of the existing fan. It probably also contains a timer.

You’ll need to remove this transformer as the new fan is a mains one!


Then you’ll need to look at the wiring that runs from the transformer to thd fan and decide if it is suitable for mains voltages and if it has a CPC (earth) conductor.

If that’s all to code then you need to replace the transformer with a suitable junction box.

EDIT. also you probably won’t need the pull switch on the new fan. I expect the fan will come on and off with the light. I hope that’s what you want?

I see. Thanks for the information.

I don't know where the SELV device itself is, the SELV extension is a 20cm or so length of 'small' core wire connected to the fan at one end and terminal-blocked to a thicker core wire at the other which also only has a live and neutral, no earth is present.

This thicker wire then disappears into the wall behind the fan. No idea as of yet where it runs after that.

I suppose trailing the wire to find out where the transformer gubbins is will be my next step. Given what I've gathered from what you've said, it's going to entail running a new wire from a junction box, which will mean ripping open the wall. I'm disliking what I know already.

My current setup has always worked manually and independently to the bathroom light switch and I hadn't intended to spruce this functionality up at all, just swap out the fans and let me decide when I want it on or not.

 

[Taylortwocities]

May be easier then to replace the existing fan with another 12volt one.

 

[JohnD]

What is the height of the fan above floor level? (This is important)

Is it above a bath or shower tray?

Is in in the wall or on the ceiling?

Do you have access from above, for example in a loft?

Where is the transformer?

 

[eitherxor]

What is the height of the fan above floor level? (This is important)

Is it above a bath or shower tray?

Is in in the wall or on the ceiling?

Do you have access from above, for example in a loft?

Where is the transformer?

- The height of the fan is 1.9m above floor level.
- The fan is 1m above the sink in one corner; bath is in the opposite side corner.
- I do have access from above via a loft
- I don't know where the transformer is, I need to find that

 

[Taylortwocities]

A 230v fan is (these days) ok for installation in most locations in a bathroom. In summary:

a suitable 230 V extractor fan may be installed both in zones 1 and 2, and outside the zones. If an extractor fan is installed in zone 1 or 2 it must be protected against the ingress of moisture to at least IPX4 and be suitable according to manufacturer’s instructions. Regulation 701.512.2 requires that equipment exposed to water jets (for example, for cleaning purposes), shall have a degree of protection of at least IPX5. An extractor fan supplied from a lighting circuit for a bathroom without a window should have its own means of isolation, as otherwise replacement or maintenance of the fan would have to be carried out in the dark. An isolation switch for a fan with an overrun facility will need to be triple-pole (switch wire, line and neutral), and must be installed outside zones 0, 1 and 2.

Plagiarised from https://electrical.theiet.org/media/1450/section-701.pdf

The OP needs to either:
1. Find the transformer and confirm the wiring is suitable (if its only 2 core it might not be)
or
2. Replace with another 12v fan

 

[EFLImpudence]

An extractor fan supplied from a lighting circuit for a bathroom without a window should have its own means of isolation, as otherwise replacement or maintenance of the fan would have to be carried out in the dark.

What nonsense.

Where does that come from?

Other than the document you quote - wot someone have thought up

 

[JohnD]

It sounds like the fan is in the wall, not the ceiling.

As it is opposite the bath you can fit a mains fan

As you have access from above it would not be difficult to provide power from the ceiling rose (I assume you have a ceiling lamp)

When you go up there you can look for the wiring and the transormer. If you are lucky there might be conduit to the fan.

 

[Taylortwocities]

Where does that come from

From the IET, the people what write the regs. I provided a link as to the source and quoted it in full. Don’t shoot the messenger.
In. As my event, the OP does have an isolator switch

- I do have an isolator switch just outside the bathroom

 

[EFLImpudence]

From the IET, the people what write the regs.

I doubt that. Wiring Matters is described as a free on-line magazine so likely no more authoritative than, say, the IET forum nor a NICEIC article.

I provided a link as to the source and quoted it in full. Don’t shoot the messenger.

Fair enough. You must therefore think it relevant and of value.

I am saying it is a ridiculous thing to state - isolators dependent on presence of window.

In. As my event, the OP does have an isolator switch

Yes, probably with a view to electrical safety rather than being able to repair a fan with the light on.

 

[eitherxor]

Thanks for all of the input you lot. It appears to me that Taylor does essentially clear up my thoughts on paper, and John is right in terms of what I'll have to do in practice going forward. Don't let that stop any debate, though! All fairly interesting to take in.

Hopefully the transformer setup will be in the loft, accessible, and have been done in a way that isn't a clusterfuck to alter. The biggest job in such a case would be replastering the damn bathroom wall from ripping the current twin core out. I'm renovating the whole bathroom and so I have an almost endless number of jobs to do, the fan being the least thing actually required. With it not being a simple swap over, I'm prepared to push this down the list until I feel I've gathered enough information on the details and at a time that won't hold up other graft.

What's the chances of the transformer being in/behind the fused switch for the fan, out of curiosity... Would it even fit... Just thinking aloud here. I'm get more categorical and check when I can justify it.

Thank you all again.

 

[Taylortwocities]

Not sure on your setup but, if the fan is in or near the ceiling, and the isolator switch is up at ceiling level, then it’s a simple job to run a new bit of 2-core and earth between the two and use your mains fan.