N Cook wrote:

There's a simple explanation for that one.
The neutral retaining screw is connected to the prong that goes in and out
of socket each time and vibrated each time.
The live one is decoupled from a lot of that vibration by the fuse.

But why do christmas tree lights always fail to light when reused the next
year but were fine before packing away, at least one bulb is always loosened
over that 11 months. ?


Planned obsolecence. Most people are too lazy to find a bad bulb, so
they get to sell a new string. ;-)

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida