Electric Light Switch Sizzles, Sparks then Smokes

[Jason Hatfield]

All,

I preface this post by stating that before proceeding with this deal I will ABSOLUTELY have an electrician check out this house.  However I thought I would toss this up and see if anyone has a theory as to the issue and possible severity.

I believe the house was built in 1961 and it looks like they had the fuse box switched over to a breaker panel in 2002.  I was touring the property and flipped on the switch to the hallway light. After a moment I noticed a humming noise and the light went out.  I turned the switch to the off position and noticed a small amount of smoke coming out from behind the face plate.  I turned on my video camera and repeated the process.  If you check out the YouTube link you can see a blue spark from inside the switch and then the puff of smoke when I turn it off.  Here is the link:  https://youtu.be/6wLlTPAeNLw  

My first thought was aluminum wiring but I didn't think they started using aluminum wiring in houses until the late 1960's. I was also very surprised that the breaker didn't trip!

I would love to hear from anyone who has had a similar issue and what the outcome was. 

Note: The house is in PA South West of Philly

Thanks!