What's going on with this junction box?

Post date: 2022-01-24 10:16:34
Views: 377
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:
How the Jensen Huang affair changes the outlook for U.S.-China relations
Apple, Alphabet and Uber survived major founder transitions. Nvidia will be a harder test
Donald Trump Jr. exits advisory role at Kalshi prediction market
NHL’s next media deal will test the league’s strength
This cybersecurity stock is down nearly 20% over the past month. KeyBanc says it's a buy
Stargate SG-1: Prometheus Rewatch
Line of Fire: Guest List
Movie: Behemoth!
Bessent: Treasury has wanted Megaspeed restrictions for months, but Commerce is in charge
CNBC's Official NHL Team Valuations 2026: How the 32 franchises stack up