Power provision at seats in lecture theatres

I have designed 6 lecture theatres I am refurbishing this summer  with one twin power outlet with USB between each pair of seats. This is in response to the growth of mobile devices now being used by students and the positive response I had to similar proviaion I made last year in an IT lab see here 
It is co-incidental that a collegaue of mine at Birmingham University, James Rutherford initiated a discussion on the SCHOMS forum www.SCHOMS.ac.uk. about this very provision.

In particular James asked about the provision of power below the work surface in a traditional lecture theatre.
My opinion is that that this is a bad idea for several reasons. I am intersesetd to learn how others are dealing with this surge in demand in lecture theatres in particular?

My reply to James is below.

Interestingly, I am installing some this year but have decided that they should be mounted on the tops. The space they take up is minimal and one twin 240v and usb unit can be shared by two seats.

I did some very basis research and discovered  that the ones under the desk are not well used compared to ones easily accessible, this was confirmed by or furniture supplier. In my opinion having a socket and mains leads under desks where people are continually plugging and unplugging is not desirable.

I installed some last year on the Top Tech Venus desks in an IT lab and they were so well received that I am installing them in 6 lecture theatres this summer. I have gone for a pattress similar to this http://www.cef.co.uk/catalogue/products/68115-2-gang-pedestal-box-2-lugs-with-earth-terminal-sold-in-1-s

One thing to beware of is that you do not want knockout on the sides or back, just the underside.