It looks like the beginning of the end of electric vehicles!

Back in the olden days, there was separate billing for lighting and power.  People responded by plugging their irons and toasters into a light socket.

I thought that rate for lighting was normally higher than the rate for power - as often the local corporation operated both the gas works and the local generating station - so small amounts of electricity used for lighting were competing against relatively expensive gas, while electricity for "power" was competing against rather cheaper coal.

Hence the 15A to 5A adaptors.

BC plugs were popular in rooms that had a light but no sockets (quite common at one time).

     - Andy.

The idea that people plugged electric irons into lamp sockets to save money is an urban myth.

On the once common "two part" tariff, electricity for lighting was charged at a HIGHER rate than that used for power purposes. In the early days of electricity supply it was used almost entirely for lighting.

The electricity companies therefore had invested a lot of capital in plant that only produced significant revenue between dusk and midnight.

There was therefore considerable interest in "building the daylight load" by offering lower rates for non lighting uses. 

Electric irons were indeed often plugged into lamp sockets, not to save money but because there was either no power socket, or it was already in use for some other appliance, or was not conveniently situated for use of an iron. Use of a power socket would have been CHEAPER if separately metered.

The idea that people plugged electric irons into lamp sockets to save money is an urban myth.

On the once common "two part" tariff, electricity for lighting was charged at a HIGHER rate than that used for power purposes. In the early days of electricity supply it was used almost entirely for lighting.

The electricity companies therefore had invested a lot of capital in plant that only produced significant revenue between dusk and midnight.

There was therefore considerable interest in "building the daylight load" by offering lower rates for non lighting uses. 

Electric irons were indeed often plugged into lamp sockets, not to save money but because there was either no power socket, or it was already in use for some other appliance, or was not conveniently situated for use of an iron. Use of a power socket would have been CHEAPER if separately metered.