Ray, I understand the difference between 2.5mm and 1.5mm cable and the respective performance criteria.
All of the retailers I have in mind are "reputable retailers". Unless one knows their onions, how would most buyers differentiate between what is offered on say Amazon or Ebay.
Hi, I am happy with what you have said. My problem is with some traders on e bay, possibly Amazon Marketplace and some other on line sellers who import from the far East and are selling things that are simply not up to the standard required and are potentially unsafe. In most cases unless you take them apart you might not spot the problem, but some can be downright dangerous. Generally the give away is they are too cheap, but many are tempted.
Whilst I know most of the theory, I am not an electrician and prefer to buy as safely as possible, We have a very reputable caravan dealer just up the road and they are pretty competitive, so in general I would go to them as to date I have not seen anything there that looks substandard.