Amps are amps, and AC or DC makes no difference to the current rating. The skin effect is minute at power line frequences and at the modest currents handled by plugs and sockets.

The older type socket outlets were simply better designed and manufactured and could handle at least  twice the design current, and even more than that short term. Misuse of 5 amp sockets for 2 kw  portable heaters was very common and almost never had any serious consequences.

In my mispent youth I used a Baby Belling cooker with a FLC of about 15 amps from a 5 amp plug and socket  which never even got warm. The oven used about 8 amps and was run 24/7 in cold weather for space heating.

More recently I found a 24 volt DC microwave oven with an input of over 30 amps being used from a 15 amp plug and socket. It only got slightly warm  a similar outlet was used for for a 24 volt kettle rated at 25 amps.

And yes it was permitted to install 3 of 5 amp sockets on a 15 a 15 amp circuit., in practice more than 3 were often fitted

Numerous 2 amp sockets were allowed on a 5 amp circuit.

two 15 amp sockets were oncle allowed on a 25 amp circuit.

we now have 13 amp sockets that are unreliable at more than about 8 or 10 amps continually.

Amps are amps, and AC or DC makes no difference to the current rating. The skin effect is minute at power line frequences and at the modest currents handled by plugs and sockets.

The older type socket outlets were simply better designed and manufactured and could handle at least  twice the design current, and even more than that short term. Misuse of 5 amp sockets for 2 kw  portable heaters was very common and almost never had any serious consequences.

In my mispent youth I used a Baby Belling cooker with a FLC of about 15 amps from a 5 amp plug and socket  which never even got warm. The oven used about 8 amps and was run 24/7 in cold weather for space heating.

More recently I found a 24 volt DC microwave oven with an input of over 30 amps being used from a 15 amp plug and socket. It only got slightly warm  a similar outlet was used for for a 24 volt kettle rated at 25 amps.

And yes it was permitted to install 3 of 5 amp sockets on a 15 a 15 amp circuit., in practice more than 3 were often fitted

Numerous 2 amp sockets were allowed on a 5 amp circuit.

two 15 amp sockets were oncle allowed on a 25 amp circuit.

we now have 13 amp sockets that are unreliable at more than about 8 or 10 amps continually.

broadgage said:

Amps are amps, and AC or DC makes no difference to the current rating.

Except for two things:

1. The fuse itself - BS 1362 fuses are definitely these days AC only.

2. If the standard includes tests for insertion and withdrawal on load, then, if those tests are carried out with AC only (which the current and recent versions of BS 1363-1 for plugs and BS 1363-2 for socket-outlets have done, but which were not included in BS 1363:1947), then the increased arcing effects with DC won't be tested for.

Point 2 especially worth considering, because BS 1363-1 plug pins are these days often hollow (the practice started around 40 years ago if memory serves, roughly at the same time as moulded plugs arrived on the scene).