What exactly does "Hospital Grade" mean?

Here is a link to the official explanation. It's a PDF, you need a reader to view.

http://www.ul.com/regulators/ReceptacleGrades_Kurten_JF2005.pdf

Thank you Albert for the detailed info.

Reading it I notice that "Hospital Grade" means it has certain characteristics, like tolerance of "Abrupt removal" (yank the wire) which are probably important in the Hospital environment, but which IMHO are not relevant to the outlets we use for audio systems. They would be a good idea for some other plugs in my house (the ones that the vacuum cleaner gets plugged into).

It's nice for those of us that have heavy weight power cables, because they're held more securely.

Hospital grade sockets perform this function well because they're designed for health care environment where uninterrupted power is important.

There are also several commercial grade sockets that have excellent grip. Almost any brand "premium socket" is superior to the .49 cent ones used in construction of new homes and apartments.

Dozens of companies provide premium aftermarket outlets, and like power cables, some audiophiles use them and some do not.

Albertporter...Of course a tight grip would be important for a heavy PC, but the "Hospital Grade" designation does not seem to offer this feature any better than commercial grade (as you note).

When I was involved with heavy (64-pin) connectors and cables we usually provided for strain relief support of the cables, even though the connectors were a locking type.
It seems to me that, for some of the audio equipment power cables I have seen, reliance on the simple 3-pin outlet would be unacceptable no matter how tight the grip. There are readily-available 3-pin plugs (and sockets) that twist to lock. These are, I think, used for higher amperage 220 volt applications, and I often wonder why audiophiles have not discovered them.