What's going on with this junction box?

Post date: 2022-01-24 10:16:34
Views: 155
I removed a ceiling light in my apartment only to discover a junction box with wiring I did not expect. Photo here. Left to right: two-strand white wire; four-strand blue wire; single-strand red wire.

This is an old (late 1960s) apartment building in NYC, and I'm all but certain the box dates to that time. The white and red wires were connected to the old lamp. It's the blue wire that I'm confused by. (All wires had wire nuts before I removed them.) I was hoping to see a green grounding wire, but alas.

So, what's up with the blue wire? Do I need to be calling in an electrician here? Thanks for your advice.
Number of Comments
Please click Here to read the full story.
 
Other Top and Latest Questions:
What obesity drugmakers see next in the market: More pills, easier access and drug combinations
Adani group stocks plunge as U.S. SEC looks to question founder over fraud charges
Nvidia’s Huang to visit China as AI chip sales stall
Why do I get “You do not have permission to perform this operation” when editing my listing, and how can I fix it?
Social Security has 'no bankruptcy or collapse in the cards,' economist says — but benefits may change
Cramer says 'a big move is coming' for this financial, weighs a chip stock buy
Airbus CEO warns of new risks after 'significant' trade damage
Trump administration to take 10% stake in USA Rare Earth in $1.6 billion deal, sources say
Auto executives are hoping for the best and planning for the worst in 2026
Earnings playbook: Apple and Caterpillar lead a big week of reports