In article ,
The Natural Philosopher writes:

An emergency bodge is to use a nasty 'live plug' wired in backwards to
your ring main, and use th consumer unit to select which circuits are
activated. DO switch the main circuit breaker off tho. Your generator is
not equipped to feed the national grid if power is restored ...or the
neighbours lights if it isn't :-)


NOTE: This is thoroughly bad practice, probably illegal, and extremely
dangerous if you don't understand what I said.

However, it may prove useful in an emergency.

If you want to go this route, you must have much better interlocks
to ensure there's no way you can feed electricity back out of your
supply and electrocute someone working on the supply line.
This is normally done with a transfer switch.

Also, some circuit breakers may not be designed to stay live on the
load side when switched off.

--
Andrew Gabriel