Right, as he said, it is normally OK to go DOWN in size or pitch on electrics, but going up in size or pitch can be VERY dangerous.

Your best bet is to buy and use a Watt meter ( not a typical ohmmeter available at Rat Shack! ) and use that to determine if the props you are using are OK.

Also the prop you CAN use is dependant upon motor characteristics, battery power & voltage, ESC limits and heat dissapation....

With a glow engine you can swap props at will and see what works best without risking damage...
You start with the engine and work to the best prop combo.

It is NOT the same with electrics! With electrics you START with the prop ( and desired weight/performance of the plane ) and work to the electronics.


FYI:

I use a 12x7e on my .25 equivalent motors. I have blown that same motor when I forgot and put a 13x6e prop on it.

You may ( or may not ) be running your smaller 480 motor right at it's limits, so going up in size could be doubly risky.