"Dave Plowman (News)" wrote in
:

In article ,
Gary Tait wrote:
US visitors used to laugh at our variety of sockets, domestically.
Now we have only one, and they have the variety.

Not really. Domestically, for GP recepticals, there is only the the
one basic standard with a few minor variation, all backwards
compatible to the parallel blade two prong plug.

I can see that a modern three pin socket might accept older plugs, but
the other way round?


Nope, not without an adapter, which is considered by professinals
potentially unsafe, and are often used in an unsafe fashion.

I stand by the context of my original text, the lowest denominator is
the two prong parallel plug, which will fit into nearly all domestic
sockets since the 1930s. Before that the recepticals were unpolarised,
although it took until the 1970s for polarised two prong plugs to be
required on lamps and TV sets, and later some other appliances.

So, an appliance with a basic two prong plug, will fit into a two prong
receptical, a U-Grounded 3 prong vertical slot 15A receptical, and the
"T" slot 20A general purpose receptical. An unpolarised appliance with
also connect to a pre 1930s unpolarised receptical or light socket
adapter or a 10-15 receptical (whose slots were designed to accept both
angled and vertical prongs).