What's going on with this junction box?

Post date: 2022-01-24 10:16:34
Views: 211
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:
Jim Cramer fears SpaceX's IPO could be 'destructive' for the rest of market
We traded our smartphones for flip phones for 4 days—and learned that ditching modern technology is harder than it sounds
Cerebras' blockbuster IPO boosts hype for SpaceX and OpenAI, but crowds out smaller players
FDA shuffles top drug, biologics leaders in latest shakeup
Trump touted Palantir on Truth Social after buying the company's stock, records show
What are the current weather conditions in northern BC, AB, or SK?
Fellow Californians, How are You Handling the Governor Primary?
Are there any good free VPNs?
Special Event: Eurovision 2026: The Grand Final
Movie: Mortal Kombat II