What's going on with this junction box?

Post date: 2022-01-24 10:16:34
Views: 328
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:
Higher rates will create winners and losers in bonds, says UBS. Where the bank sees opportunity
Nvidia share buyback plan gets $150 billion boost
A key test looms for the AI trade this week. Here's how Mike Khouw is trading it
Movie: Wrong Turn
Movie: Mayday
Help me refine my sleep setup so I can ideally get some
Help me solve the problem of disappearing photos
Camping kettle
Supreme Court Justice Alito will not participate in big climate change case next week
LeBron James is already boosting ticket and merchandise demand for Philadelphia 76ers