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Hello there. My dad is getting a bit forgetful and unsure of himself, but in the past did all the DIY in the house no problems.

The bathroom extractor fan has stopped working and I thought I'd have a go at replacing it as he is not confident now. He has both exacty the same model fan motor as just broke strangely even though its 23 years old.

The fan works when the bathroom light is on and there is an isolator switch so you can use the light without the fan running.

Now I want someone to run an eye over his 23year old wiring diagram as it doesn't seem quite right as the isolator+fan looks to me to be getting two live feeds meaning there could be power going to the fan when the isolator is switched off.

He further confused me when I asked him about the diagram as he said the yellow/green wire is a live earth. I know what an earth wire is, but a live earth which runs into the live connection at the fan? He also runs the live wire into the isolator coming out as the timer connection. Is that the actual live feed?

The diagram shows at the bottom the double switch(hall+bathroom light) and at the top the right hand switch and fan motor.

I've also attached the wiring diagram that came with the fan motor.

Thanks
 

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Can you show a picture of the connections. The fan has two lives because it runs on when the light is switched off, sounds and looks like the green/yellow is being used as a live.
 

David Prosser

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It looks like the confusion is the fact a green pen has been used to denote the yellow in red/yellow/blue within older coloured three core and earth wiring. It labelled correctly but drawn using green red and black. But as stated by Westward a photo of the connections if possible would clear that up.
 
It looks like the confusion is the fact a green pen has been used to denote the yellow in red/yellow/blue within older coloured three core and earth wiring. It labelled correctly but drawn using green red and black. But as stated by Westward a photo of the connections if possible would clear that up.
Ah yes didn't see the wording yellow which explains the blue.
 
Sorry about delay, but I've pretty much given up. Mainly because while the wiring a connection looks straighforward, but it's repositioning the motors frame and the wiring. Maybe making new holes etc on the ceiling and the new framework(holes for only 2 wires out of 3 don't look wide enough.

I've included some pics(Light switch, Old motor top, old motor bottom, new motor. Thanks for replying earlier.
 

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littlespark

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You wouldnt have needed to access behind the switch. You have what you need at the fan.

L - Live, to power the run on timer.
T - Switched live, from the light
N - Neutral.

L and T could be either red or yellow, depends how its been wired. 50/50 of getting it right. but its not going to be dangerous mixing these up.... it just means the fan wont work as expected.
N is blue.

You can joint the cables inside the fan housing to extend if you need to, or drill a new hole in the plastic if its more suitable.
When you take the old fan down, the flexiduct behind should come with it. Dismantle this, push it back into the void and youll be able to get your hand in and move the 3 core to a new hole if easier. Just remember to put the duct back on the new fan.
 

Lucien Nunes

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Note that the 'isolator' for the fan as shown on the hand drawing is non-compliant and potentially dangerous as it leaves the fan live even when switched off. It is shown as a double-pole fused switch that breaks the switched line and the neutral but not the permanent line. A 3-pole isolator is needed, along with a fuse if specified by the fan manufacturer.
 

Lucien Nunes

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Because whoever put it in didn't have the correct 3-pole isolator and overlooked the hazard of switching a neutral without switching the associated line.
 

littlespark

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I replaced one of these exact same fans this morning.
For a fan made by the same manufacturer, with the same serial number... it should really keep the cable access, terminals and fixing holes in the exact same positions.

Luckily i had excess cable that i pulled through, but the fixings had to be toggle screws as the old one was just held up with red rawlplugs in plasterboard and didnt line up with the new holes
 

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