Hi Madtuna
Look on the back of your power supply modules.
The input voltage range is stated there.
For example my lappy power supply says input voltage 100 - 240 VAC
50-60Hz.
In South Africa we use 220VAC @ 50Hz
The USA uses 110VAC @ 60Hz so i would be able to use my lappy over there.
Most electronic gear these days is made to autodetect input voltage and adjust accordingly.
I am sure the same will be true for the Canon 40d as I purchased mine in the States and it works fine @ 220VAC 50Hz.
Regards
Steve