In alt.home.repair, on Fri, 27 Mar 2020 09:13:01 -0400, Wade Garrett
wrote:

About to install a new 550VA battery backup-Uninterruptible Power
Source. The owner's manual says to plug it directly into the wall
outlet, not to an extension cord or power strip/surge protector.

My computer desk is not near a wall outlet and I've always plugged my
UPS into a good quality power strip/surge protector that has a four foot
16/3 gauge cord.

The new UPS has a six foot 16/3 wire as well- so I'm wondering if it's
OK to keep the same setup. I've never had any problems with it before.

I think they don't want a surge suppressor because the UPS probably has
one built in that is better quality than in a power strip, and it's
counter to one's goal for a some other surge protector to be
interrupting what's intended to be uninterruptible.

OTOH, the warning against extension cords is probalby one step from
silly. I have had extension cords that barely squeeze the plugs that go
in them, and that separate when even slightly pulled, but your two cords
don't come apart, there's nothing wrong with extension cords.