What's going on with this junction box?

Post date: 2022-01-24 10:16:34
Views: 202
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:
Apple's elevation of silicon head Johny Srouji signals sprint to build in-house chips for all devices
How Warsh can give Trump rate cuts, keep Fed independent, and make the market happy
Trump recounts Tim Cook call to 'kiss my ass,' in stark look at White House dealmaking
Marvell stands to gain from boosted Amazon-Anthropic partnership
Bike horn for warning oblivious pedestrians
I am your manager but I'm not your manager
The Way Home: The Way Home, season 4 (all episodes)
UK inflation jumps to 3.3% in March as fuel prices surge amid Iran war
Tim Cook turned Apple into a $4 trillion juggernaut by not trying to be Steve Jobs
Trump says 'I'll remember' companies that don’t seek tariff refunds