Lucky we didn't have an electrical fire.

We are the original owners of a 20 year old tract home. The outlet and lights near our bookcase in our family room have been acting up for a while. The neutral showed 45V to the hot wire. I’ve been trying to find the source of the problem for a couple weeks. I even called a friend who is an electrician and he walked me through a bunch of tests. Today I used a tone generator to track the wires but they only went down a couple feet. I went outside and found that the signal ended in the same general region. I looked inside the bookcase and found an access panel that I had never noticed before. Inside the access panel is an outlet box with a cover on it. I opened it up and sure enough, the neutral wasn’t secure in the wire nut. Apparently neither was the hot. This bookcase was an option and was added in after the house was built. From the looks of it the outlet and lights must have been added after the bookcase was installed. It's amazing that it worked for so long. 

You'd be appalled at some of the "homeowner" electrical BS I've encountered. Glad Sparky could walk you through it.

At least they put an access panel for you. 
 

ive never heard of a signal generator....   I'll have to look into them.  How do they work?

I wasn't too worried as I saw the neutral wire (white)... not a good thing, but not scary. Then I kept scrolling... bad connection on the "hot" wire - bad juju!

Glad ya got that fixed.

Not to mentioned that a concealed junction point and not in a box on top of that is illegal / against code.  I didn't see a ground wire in the the picture either so that's a concern.  Yikes, the thrills of homeownership.

You can fix that with a new work box with a blank cover, that gets the wiring into a box and accessible because you can see the blank cover / know there's a junction point.   Need to find the ground wires though and make sure they're bonded together. 

That's some scary stuff, my buddy had something very similar on his new build.