Is that tape wrapped around the lower half of the bakelite shell of the lampholder?
At least it's not one of those awful paper-lined metal shell sockets....where you get a nice shock after the paper gets rotted away from the heat of the lightbulb. Why haven't they been supplanted by Bakelite shells yet?
I doubt the heat coming from those pipes is any good for the rubber (or is it plastic?) zip cord there....
