Is it OK to caulk around an outdoor electrical panel or meter base?
Do you have siding installed behind the electrical panel? 
If there is siding behind the panel, then do not caulk it to the siding.

If there is no siding behind the panel, then you can caulk the outside perimeter of the panel. If you have vinyl or steel siding, then you should trim it with J-channel and caulk the J-channel to the electrical panel. If you have any other kind of siding, then you caulk the top and sides but usually not the bottom of the panel to make sure you don't trap any water behind it.