I have seen old service cables in 4mm, or more likely an old imperial size similar to 4mm.

Sometimes they go bang, but many survive. Back in the good old days, household services were often only 20 or 30 amps. Who could want more than that ! I have seen old electricity meters designed for 10 amps at 110 volts DC. Ample for lighting and a radio set. Not many houses contained more than a dozen lamps. And whilst the odd 100 watt lamp might have been used, the average lamp wattage was probably about 40 to 60 watts.

Kitchen----------------one lamp of 100 watts.

Living room-----------one lamp of 100 watts, or in the better class home, an "electrolier" with four or five 40 watt lamps.

Stairs/hall/landing----three lamps each 25 watts.

3 bedrooms------------each one 40 watt lamp

Bathroom--------------two lamps each of 40 watts.

WC----------------------25 watts.

A 10 amp service at 110 volts would be fine for that lot. One could probably get away with a 700 watt electric kettle or a 700 watt clothes iron as well as the lights. Service cable was probably about 2.5mm There were still a very few 110 volt DC services into my lifetime. 

I have seen old service cables in 4mm, or more likely an old imperial size similar to 4mm.

Sometimes they go bang, but many survive. Back in the good old days, household services were often only 20 or 30 amps. Who could want more than that ! I have seen old electricity meters designed for 10 amps at 110 volts DC. Ample for lighting and a radio set. Not many houses contained more than a dozen lamps. And whilst the odd 100 watt lamp might have been used, the average lamp wattage was probably about 40 to 60 watts.

Kitchen----------------one lamp of 100 watts.

Living room-----------one lamp of 100 watts, or in the better class home, an "electrolier" with four or five 40 watt lamps.

Stairs/hall/landing----three lamps each 25 watts.

3 bedrooms------------each one 40 watt lamp

Bathroom--------------two lamps each of 40 watts.

WC----------------------25 watts.

A 10 amp service at 110 volts would be fine for that lot. One could probably get away with a 700 watt electric kettle or a 700 watt clothes iron as well as the lights. Service cable was probably about 2.5mm There were still a very few 110 volt DC services into my lifetime.