On 3 Jul, 19:05, "Dave Plowman (News)" wrote:
In article . com,
wrote:
On 2 Jul, 16:45, "Dave Plowman (News)" wrote:
In article .com,
wrote:

Who cares? I unplug and plug in items that are turned on all the
time, worst case you get a little spark, it doesn't cause any
problems. It's not hot enough to pit the plug prongs or contacts.
Its well known that repeated small sparks make a total mess of the
contact surface. This was one of the problems of our olf round pin
system half a century ago.

You'd have to explain that. Most of the old round pin sockets were
switched - unswitched was a short lived fashion with 13 amp stuff. At
least in my experience.

The old round pin sockets were far more likely to be overloaded,
though.
Round pin systems did not consistently have good contact arrangement,
leading to frequent bad connections between plug & socket, producing
the same type of damage as occurs with unswitched sockets.

I'd say it depended on the quality of the fitting

The problem is transmittable, thus only one bad socket was needed for
the problem to occur and spread to the others. So good sockets went
down too.

The way it occurs is one bad contact occurs, the plug pins get
damaged, and when damaged pins are inserted into a good socket, bad
contact occurs due to copper oxide and a rough surface. So the good
socket is damaged. Plug something else into it, that plug gets damaged
etc.

Slow process, but have seen it happen. AFAIK its the only electrically
transmissible disease


- given most plug/socket
arrangements have round pins. Including the heavy duty BS4343 type.

Nowt wrong with round pins. The problem is that some of the older
sockets didnt implement contact springing, either at all or
effectively. Sometimes the split plug pin was the only sprung part,
which is no good at all on 15A 3 pin plugs.


NT