408.36(D) Back-Fed Devices. Plug-in-type overcurrent protection
devices or plug-in type main lug assemblies that are backfed and used
to terminate field-installed ungrounded supply conductors shall be
secured in place by an additional fastener that requires other than a
pull to release the device from the mounting means on the panel.
Does look weird. I'd visit the website of the breaker-box manufacturer or
call their customer service department to see what they recommend. I assure
you they don't want to be named in a lawsuit should your house burn down and
everybody, including your fish, die.
Hint: If you hear a gasp, you'll know.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.