What's going on with this junction box?

Post date: 2022-01-24 10:16:34
Views: 241
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:
Can you get a loan for a wedding? The do's, don'ts and alternatives
2-year Treasury yield rockets higher as many Fed officials signal possible hike this year
Stargate SG-1: Desparate Measures Rewatch
Mr. Queen: Full season
Earth Wind and Fire - To Be Celestial vs. That's the Weight of the World
You had one job, bank.
auto shop keeps postponing major repair
Separating hobby and work
Treasury 2-year yield post-Fed spike 'exaggerated' or is there room for more? Strategists weigh in
Why Wall Street banks and foreign borrowers are rushing to tap China’s cheap money