The gfi outlet I have looks like its controlling the light and also a lower receptacle directly tied in. I want to add a exhaust fan. I don't think I can re-wire this cleanly over my head .... But .. if I'm happy for fan to always be on with light can I just Splice directly into the line going to the light. Eg Cut existing line - now have 2 blacks 2 white and 2 ground Have new line for exhaust comming from exhaust. 1 black 1 white 1 ground. Tie off black x 3 Together Tie off white x3 together Tie off ground wires x.3 together That's it .... ???

The connections you are making should be in some sort of junction/outlet box and not just in the middle of a wire run. But assuming the currently installed white, black and ground are all hooked correctly then the hook up you are proposing should work fine.The fan must not over load the existing circuit and the wire should be sized correctly to the circuit being connected too. (i.e. use 14 ga wire for a 15a circuit and 12ga wire for a 20a circuit but you should not splice in a 14ga wire into a 20a circuit.Make sure the power to that circuit is off when you are working on it.

As War Eagle stated, you can do this, but ensure same gauge wire is used, ties are in a junction box, and circuit current is not exceeded.My bathroom downstairs is done this way. The fart-fan comes on with the light, and is tied together in a junction box, black to black, white to white, ground to ground.

Thanks guys.So .....1) How to determine that curcuit load is not exceeeded - no idea :shrug:2) I assumed all wiring was 14/2 ..... so thats what I bought ...... current 14/2 I bought is white ...... this electrical wiring is yellow ......... I'll have to crawl up and see what markings ...... etc.

First thing you will have to do is find out what loads are on the specific circuit you are planning to use for the fan. It might be as simple as reading the fuse panel to see what is connected to that breaker. Some homes have this information actually listed on the fuse breaker panel. If it is there it might say something like (bedroom 1 outlets and lights, hallway lights and outlets, etc.) In this example you would go to each light socket (on this circuit) and see what wattage light is there and add up all the totals for every light that is on that same circuit. This would give you watts used by lights. Divide total watts by 120 to get the load in amps (i.e. 450 watts/120volts = 3.75 amps). Then go to each out let on that circuit and see what's plugged into it (or planned to be plugged into it) and look at the label of the device to determine what the load is (watts or amps) created by that item and then convert them to amps if they were listed in watts. Add all the amps together for a total connected load on that circuit.You mention 14 ga wire, well that is capable of a maximum of 15 amps and as a general rule of thumb you don't want to connect more than 80% of the maximum load capability of wire and it's respective fuse or breaker to any circuit. SO in this case 80% of the 15 amp circuit would be 12 amps. Therefore, you would add up the total of all connected load (in amps) and then add up the load of this new fan you want to add to this circuit you are looking at. Then if the total is still less than 12 amps total you are good to go.Now if the fuse panel doesn't contain the info about what is connected to the circuit you are considering using then you have some work to do. One option would be to turn on all the lights and then go turn the breaker off and see which lights go out. Then go around and add all the watt value of those lights that go off when that breaker is off. Convert the watt values to amps as shown above. Now with the breaker off also see if anything else that was on is now off (like a TV or stereo etc). Now take a small plug in load (radio, light fan etc.) around to all the plug in outlets (then plug this small plugin load you are carrying around) to check and see if they are energized now or not. Once you have found out what plug in outlets are off (because of breaker that is now turned off) then do as I mentioned above and add up all the load of the things that are now plugged into those outlets (or that you plan to plug into them in the near future) and then add into the sum of those loads the load of the new fan you want to connect. Again if the total is 12 amps or less than you should be good to go.Hope this is clear enough detail to follow.Now one thing you need to be sure of is once you have determined which circuit it is you want to tie into make sure the fuse/breaker for that specific circuit is a 15 amp rating if you are going to use 14 ga wire. If it turns out that the fuse/breaker for that specific circuit is a 20 amp rating then you can't use 14 ga wire but will have to go to 12 ga wire.

GOOD INFO !!! :thumb1:Would have 2x thanked if there was a double thankyou button :)Got it all setup, going to tie in duirectly to teh junction box at the light and loop back to the exhaust fan.The wiring is 12/2 - so going to continue with that. Its on a large Amp circuit ...... going to be hard to claculate exactly the load as depends what applicances are running at the time but this is small fan with no heat lamp - so going to tie it in and monitor to make sure circuit doesnt trip.thanks guys

Just food for thought:

The standard 15A GFCI receptacle are rated for 20 amp feed through. Feed-through means that the incoming line can continue at the same amperage rating. Each "plug-in position" on a 15 ampere duplex receptacle is rated for up to 15 amperes although the entire receptacle (assuming a 20 ampere "pass through" rating) is rated for a maximum of 20 amperes.

So that could mean 15 amperes in one position and 5 amperes in the second position or any other similar combination.

The only true 20 amp GFCI receptacles usually are found in commercial location and they are generally a little more expensive than standard 15 amp GFCI receptacles are.

In the residential usage it very rare to see a true 20 amp receptacle [ GFCI or standard type ] not very many appliances that really required a 20 amp plug with 20 amp receptacle.

Got her done fellas thanks for the help.Works a treat

1 more question. Thinking of doing other bathroom tying into the light again. But this one is on a dimmer switch Bad idea ?

I wouldn't do it on a dimmer switch. Your fan would run a what ever speed your dimmer switch was set at. Might be hard on the motor. Sent from my DROID3 using Tapatalk 2