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Electrical Wiring in the Home/Electrical Wiring: Replacing an old, existing bathroom vent/light combination on single switch/pole


New Box W/ Existing Wiring
New Box W/ Existing Wi  

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Closer View  
So we bought a brand new Harbor Breeze (Lowe's) 2.0Sone 70CFM bathroom vent and light combination this evening. Our home was built in 1996 and a family of brothers actually built it. The wiring to the master bathroom is ganged together with pairings and twist locks bundled but then we have two thick yellow gauge (not sure the thickness) wires that came into the old ceiling fan. The old unit used to plug ins into the box to connect the fan. The new one uses a molex system (much like on a computer power supply and motherboard) that plugs into the corner switch box in the unit and that leads to the fan. This link here is the unit we purchased:
So needless to say when we went to go hook it up, well we aren't sure how we are to run the wiring. The diagram tells us to take both black wires from the light and fan molex plug in, twist them together to the black wire being fed in, and then do the same with the white coming from both. Well, we would do that except both gauges of wire coming in is yellow and that is how the old was hooked up. So what I need to know is how do we hook this system up? Are we going to have to pull wiring through to use as extra or will we need to connect new wire to the existing yellow wires to get our connections or will we need to test which one is which with a voltmeter?? I Would like to provide pictures if possible. We had a utility worker who did electricity wire out main bathroom system which is the same but we looked at it and really aren't sure how he done it. We do know he hooked the green grounding wire from the new fan unit into existing wires. Any help is appreciated.
Attached two images. Let me know if you need to see the gaggle of wires, may have to go to attic or actually I can unscrew the the box and get them. Have another picture to upload but it only let me upload two. This is the switch inside the box that connects the fan to the wiring (is my guess)

I don't know what the deal is with the yellow wires is. They are not to be use outside of a conduit. If you are wiring the fan with them stop and call in an electrician.

The fan wiring: I want you to stop thinking so hard. The drawling can be very confusing but it you think about the basics it will all fall into place.

1. If you attach a hot(Black from a breaker) and neutral(White from the panel ground bar) to the light and the fan they will turn on all the time.

2. You never switch the neutral the neutral.

3. Your hot feeds two switches

4. a wire from each switch goes to feed either the fan or the light.

That is all there is to it. Forget all the weird colors and fancy connectors. They are just following the rules listed above.

I have my own rule. Never sale a client a fan light combo when you don't have to. They are junk 99% of the time.
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Electrical Wiring in the Home

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Bill Lutz


Any questions about being an electrician or doing electrical work. I can help advise people on their wiring needs, what kind of outlets and switcher to use, explain what an electrical service is and how their breakers work. I can also help them with their lighting needs. . I CAN HELP YOU UNDERSTAND WHAT YOUR LOOKING AT.


My Father apprenticed to his Father-and I apprenticed to mine, repeating an invaluable tradition of child labor and a great place to learn a trade. Beginning at the age of 13, I worked with my dad every weekend and summer vacation in homes throughout Philadelphia repairing and rewiring all levels of residential electrical systems. Studying electrical engineering and earning a degree in architecture has given me a solid advantage in solving the myriad of residential electrical problems. Generation 3 Electrical, Inc. takes pride in every job - building confidence by how we do things - by being prompt, thorough and leaving every job site finished and clean.

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