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Wiring up a bathroom exhaust fan-how to? Answered

so I cut a nice round hole in the ceiling of my bathroom. physically installed the fan.

was going to wire into the light so that the light switch would turn on the light and fan in one.

the exhaust fan has a plug- 2 prongs (i'm in australia).

the wiring to the light switch is only 2 wires.

the light wire was exposed /available half way between the light socket and the switch.

so thought that would be a good place to cut the wires (mains power off and fuses removed)

thought at first I would wire the fan in serial and that didn't work. tried parallel and htat didn't work.

I was going to wire a "power socket" on  to the cable.  the fan has a cable coming out of it with a plug .

inside the power socketty thing there places to out the wires. and then turn a screw to keep them in place (ooooohhhh , the technology talk is a flowing). so black has one socket thing to place wires in and red has 2 socket things to put wires in.

so how (and please use a diagram if it makes it easier for me) do  I wire the bastard in to work???

I've tried every combination - except using red wires in to both red wires places with turn screws in the socket thing.


in the end I left the fan out. and then had some electricians in to install wiring for an air-con, add some power points, and move some light switches. i just paid them to do the magic. it was annoying.

Next task! I have just 2 wires on ventilator with 3 wire connection, but I want to let vent timer to work! Is it possible? extra self block relay, extra pir etc. PLZ HELP!


Assuming the fan and the light are designed to use the same voltage, then these, the fan and the light, should be wired in parallel.

Strangely, you say that you that you tried wiring them in parallel and "[that] didn't work". Which didn't work? The light turned on but the fan did not?  The fan turned on, but the light did not?  Or maybe neither the light or the fan turned on?

Anyway, it would be a strange sight to see the light turned on, but the fan wired in parallel with it not turn on.

Check again to make sure the fan actually works when plugged into a power source you expect would make it run, an extention cord perhaps, or a different wall outlet. 

yeah, it was weird.

at the wires half way point between the light and the light switch I attached the fan in parallel. -that is (correct me if I'm wrong) I attached a power socket with red (+)wire going in and out on one side of the power socket and black going in and out on the other side. and then plugged the fan in.

after turning the power back on at the fuse box the light was on. it didn't matter if the lilght switch was on or off the light stayed on. the fan didn't move. I checked the fan by plugging into a regular power socket and it worked fine.

voltage in Aus is 240v. but on sundays it drops to 185v between 11am and 1pm..

I don't know for sure what you did, but I suspect you wired the fan in parallel with the light switch instead of in parallel with the light. I've attached some crude drawings. The first picture represents what I think you did wrong, and the second picture represents the right way to do things. For both the wiring is symbolized by solid lines, while the dash-ed lines represent the walls, ceiling, and floor, of what I imagine to be a sort of cube-like bathroom.

Anyway, I think the wire (pair of wires) going from the light fixture to the switch probably should be left alone, because probably all it does is go to the switch and come back.



Useful instructions. I have a situation where I need to turn on the fan from two different light switches. Either one or both. Is this possible?

The trick for doing this is called multiway switching, or at least that's what the Wikipedia article calls it.

A typical example is a hallway with one light and two light switches, located at either ends of the  hallway.  Flipping either of the switches toggles the state of the light.  If the light was off, flipping either one of the switches will turn the light on.  If the light was on, flipping either one of the switches will turn the light off. 

This example of a single light, with two light switches, requires two so-called 3-way switches, and the Wiki article shows how the wiring is done.

I assume the same trick would work with a fan.

I think the Wiki article is clear, but there are a bunch of other tutorials out there on the same subject.


that's exellent.

your wrong picture was what I was doing.

I'll try the right way.

Thank you very much for taking the time to do that.


At the light socket there should be two wires there. If there are 3 then one of them is the ground. You must connect the fan to the two power wires in parallel. You can't connect in series. Also the fan MUST be the same voltage as the light. I not in Australia so I don't know what the voltage is there.

+1. If parallel didn't work, there is an error in your wiring.

Red isn't typically used in the US; here housewiring colors are primarily black, white, and green. So there really isn't much I can suggest beyond checking other circuits -- or finding local expertise -- to determine which wire is hot, which is neutral, and which is safety ground. Fan and light should be connected in parallel between hot and neutral. And you SHOULD have a safety ground connection for that ceiling fan.

I didn't know you guys ever used red ? Since when, or when was it abandoned ?

We've just abandoned red and black and gone to brown and blue for house wiring here.


Red can be used to replace black in single phase. In 3 phase red is L1.

I've occasionally seen red used in cables with more than three conductors.

Also, when altering house wiring, make _SURE_ that whatever you're doing meets local electrical and fire code, or the former may cause the latter. In particular, splices should always be done using appropriate techniques (in the US, that's usually wire nuts applied to a tightly wrapped junction), and inside suitable electrical boxes (so that if the connection fails there's no risk of sparks igniting anything else). The outlet, similarly, should be mounted in a suitable box.

You may want to ask a local friend who has more experience with this to help you. The best way to learn is to watch someone who is no longer making beginner mistakes.

Which is kind of the point I was making.It was only an aside. Its surprising that something that is trivially taken for granted in one place is completely banned in another...I bet they cause a lot of fires.

> I bet they cause a lot of fires
.  If that were so, they would not be acceptable under NFPA and NEC (pretty much THE electrical code in the US) codes.
.  I really don't understand how you came to that conclusion. I've used wire nuts for decades in both residential and industrial applications and have seen no incidents of any sort that were traceable to a faulty wire nut (although I'm sure that there have been a very few). Undoubtedly, there has been the occasional problem caused by faulty installation, but that is true of any method. When vibration may be a problem, a few wraps of 33+ will usually take care of it.

Used properly (on solid copper wire, with the right nut for that wiregauge), wirenuts may actually be a more reliable connection for house current than crimp connectors or soldering would be. They're slightly vulnerable to vibration, but most houses really don't vibrate very much.

Often, items like this are based on one or two local incidents -- or even just custom and prejudice -- and don't reflect the actual odds. As another example: Every US locksmith "knows" that you never mount a lock with pins at the bottom if you can help it, since that increases the risk of crud accumulating in the chambers and causing a malfunction -- yet that orientation is apparently preferred in much of Europe.

But if you don't follow code, then if anything *does* go wrong you risk the insurance company refusing to pay... not to mention other possible liabilities. That's a good reason to follow the rules even if you don't completely agree with them.