Bathroom fan/light wiring question

[Tr10av]

I recently installed a bathroom fan where one did not exist previously. I just finished wiring it and have a problem I am not sure how to correct.

Originally from the light to the light switch there was one black wire and one white wire.

Coming out of the fan is a black, white, and ground. I installed a junction box in the attic as getting the bathroom fan wire through the wall was impractical. I cut the wire running from the light to the switch (1 blk/1wht) and put both cut ends in the box along with the fan wiring. I wire nutted the 3 blk wires together and the 3 white wires together and left the ground as I'm in an older house.

When I turned the power back on the fan now runs when the switch is off. When the switch is turned on the lights turn on and the fan turns off. I would like them both on when the switch is on and both off when the switch is off. Any help and advice would be much appreciated.

[Greg]

The wires to/from the light may not have been a hot and a neutral as you might expect, but what is referred to as a "switch leg" meaning they probably were both hot when the switch was on.  This is how it would be wired if the main power came into the light box first, and the wires to the switch only switched the hot (black) wire that powers the light.

You'll need to run a separate neutral to the fan, and then use the same switched hot that the switch leg controls for the light as the hot for the fan.  Use a tester to determine which wire to the switch is the "line" and which is the "load", meaning which is hot and which is hot when the switch is on.

Not as easy as you'd hoped.

[Spork]

If it was a switching leg... and if it was done correctly* ... whomever wired it should have designated the white/neutral as hot by marking it as such at each end.  Often this is just done by wrapping the end with an appropriately colored tape.  In this case, it would have been black... and you might have just thought "oh hey, look someone used electrical tape."  But... it could have been a clue that what Greg describes is correct.

You may want to take a multimeter and step through this... sorting out what is hot... what is neutral... and at this point, sorting out what black/white pair goes where.

*I'm not an electrician... I really go by observation of how stuff is done.

[Tr10av]

Thanks for the replies everyone. You are correct the neutral ran directly to the light and the hot wire was run to the switch and then back to the light. There was no electrical tape but I now know that is the proper way to label this configuration and have done so.

In order to fix the issue I simply ran the bathroom fan wiring to the light fixture and connected the neutral and hots at that point which was after the switch and now works perfectly. Not as easy as I hoped but now it works as advertised.

Thank you for the informative help.

[Greg]

Glad to hear you figured it out.  Next term, you will study "3-way" switches and their variants. :)

[Tr10av]

Glad to hear you figured it out.  Next term, you will study "3-way" switches and their variants. :)

I just got the Wiring Complete book on home wiring and have some other fun things to do such as take an outlet off of a switch so that it is always on and turn it into a switch for a soon to be installed ceiling fan.  I may be back with more questions but so far this book is very informative and very detailed.

[Greg]

I just got the Wiring Complete book on home wiring

Is this book green?  I have one too I think, if it's the same one, but anyway it's very helpful.  I keep it my electrical tool box.

[Tr10av]

I just got the Wiring Complete book on home wiring

Is this book green?  I have one too I think, if it's the same one, but anyway it's very helpful.  I keep it my electrical tool box.

It's this book here: http://www.amazon.com/gp/product/1600858465/ref=pd_lpo_sbs_dp_ss_1?pf_rd_p=1535523722&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=1600852564&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1Y9B7BH95Q5TPF4PT0FF Just did a cursory scan but it seems to be a great starting point.

[TomTX]

I need to tackle the same project (new bathroom fan, currently just a wall mount light)

I do need a separate switch for the fan and actually was thinking about putting it on a timer.

I guess I will be fishing new wire up from the current switch box. Is mounting a second switch above what i should do, or break out the original box and install a wider one for a dual switch?

[Greg]

Consider a switch that does both, I often recommend to my clients one that operates light and fan, and delays turning off the fan when it's switched off.  Like this one:
http://www.amazon.com/gp/product/B00ACY59GO/ref=oh_aui_detailpage_o02_s01?ie=UTF8&psc=1

You still have to run another wire to the light/fan location, or replace the 14-2 (or 12-2) with 14-3 (or 12-3) wire.

[ctmustache]

Consider a switch that does both, I often recommend to my clients one that operates light and fan, and delays turning off the fan when it's switched off.  Like this one:
http://www.amazon.com/gp/product/B00ACY59GO/ref=oh_aui_detailpage_o02_s01?ie=UTF8&psc=1

You still have to run another wire to the light/fan location, or replace the 14-2 (or 12-2) with 14-3 (or 12-3) wire.

This looks great but pricey!!!