Freezer-Extension Lead Exclusion-Guarantee.

A similar load of protectionist nonsense abounds in the form of changing the moulded on plugs on items such as washing machines/tumble dryers etc.

Seems the warranty is bust if you change a 13A plug.

I have swapped a few due to overheating at the socket outlet which has resulted in the two becoming fused together in a messy molten lump.

Root cause is usually down to the fitting of some cheap chineseum socket outlets from poundland or wherever.

Customers usually want their kit back up and running asap and are not unduly concerned about any warranty issues.


Whilst on the subject of plugs - which would you say had the largest contact area in terms of pin shape - round? (as in the old 15A types) or the present 13A square ones?

I would have gone for the round option myself because arguably, the corners of the square pins do not actually make any firm contact with the female receptical.

Whilst on the subject of plugs - which would you say had the largest contact area in terms of pin shape - round? (as in the old 15A types) or the present 13A square ones?

I think one of the old arguments in favour of square/flat pin plugs was that reliable contact area was greater - initially because it's far easer to manufacture two flat surfaces than two round ones of precisely the same radius (if the radius of the socket and pin differ even slightly the contact area shrinks very significantly) - and in service as things wear - a flat (worn by another flat surface) surface tends to remain relatively flat - whereas wear on circular ones tends to increase the radius on the socket contacts and decrease the radius of the pins.


   - Andy.

In all cases the actual contact area is a very small fraction of the total metal surface - as noted cylinders inside cylinders have only stripes of contact area - the springyness of the socket is key to a decent grip with some wiping action.  I suspect we all have at some point found a cooked 13A plug stuck in the socket, and had to change both, although you may think that we only need a square mm or so of cross-section for the current rating we are trying to achieve. In practice, with corrosion, mechanical mis-alignments, wear on the contact faces and so on, we may not get even that.

I nice clean 13 plug in a nice clean 13A socket probably has quite a bit of rating in hand if the surfaces are all perfectly true and polished. The problems arise when after a while this is no longer true. Similarly, heating of the fuse and its clips, over and above the fuses own ohmic  self-heat, can be caused by the same age related issues, And then we have the problem that heat tends to relax most of the materials you might like to use for springs, and it all spirals down pretty sharply.


I think the CEE form plugs are more successful under overload and abuse becuase there is much more metal mass for cooling, and being more enclosed, corrosion and damage are slower to appear. not because of some property of round  vs. square pins.