What does a "1 Gang" mean when talking about electrical boxes?
It refers to the width of the box. A 1-gang box is wide enough for a switch or duplex receptacle. The idea is that you can "gang" up electrical components in the box.
The n-Gang terminology is also used in the UK, but with somewhat different meaning.
- For sockets it is similar, except UK plugs are bigger and not normally stacked two on top of each other. So a 2-Gang is wider than a 1-gang and has 2 sockets. The dimensions are of course different from the US ones.
- Blank face plates are similar. A 2-Gang plate is the same size as a 2-Gang socket.
- For switches it refers to the number of switches. 1-Gang, 2-Gang and 3-Gang switches may be the same size, but have 1, 2 or 3 switch buttons.