For "équipé" I prefer "fitted". It sound to me as though they mean that the socket outlet comes fitted with plugs. Lots of possibles for "bloc multi-prises" :
- multi-plug & socket
- multi-plug & socket outlet
- multiple socket outlet (www.marineparts.com)
- multi-ways socket/adapter (www.clefmusic.freeserve.co.uk/audio.htm )
- multi-socket
- multi-block
(http://www.kingston.ac.uk/safety/risky.htm)
- adapter (http://www.detir.qld.gov.au/hs/cafeonline/kitchen/kitchenckl...

We commonly also refer to them as "adaptors" (adapter) in the UK, although I suppose that is really the correct term to be used for when there is some conwersion. Still, where would the charm of the language be without odd things?!