Won't the graded card slabs melt below 350?

[the 'stache]

I've been looking into different fire safes to store my more valuable cards. I don't want to get a safety deposit box at the bank because I want to actually look at my cards. And I've found a few that are reasonably priced, offering an hour of fire protection for fires up to 1700 degrees. Sounds great, right? Well, it keeps the internal temperature at or below 350 degrees.

If I've got graded cards in this safe, they'd melt, wouldn't they?

I know different kinds of plastics melt at different temperatures. I'm not sure what kind of plastic PSA, SGC and Beckett slabs incorporate, so I can't tell what their melting point is.

Do any of these safes offer any real protection against fire? I know some of these questions might get too scientific, but I figure that you guys have some nice collections, and this kind of question has to have come up before.

I only live a few blocks from the nearest fire department. Assuming there was a fire, you'd think they'd respond pretty quickly, and get the fire under control. But how long does it take for a fire to get hot enough to heat a fire safe to a point where the contents are placed in harm's way?

Outside of spending several thousand dollars on a custom built safe, or storing them at a bank, what kind of options do I have that will provide some protection? I don't need a huge safe. 2 cubic feet should be plenty.

I guess I'm just looking for some input from you guys, seeing how you'd have the same concerns I do.

Thanks.