Anyone remember the old Reyrolle plugs?, these were made of cast Aluminium?, and used a Scraping Earth contact arrangement. They were banned here in 2000, we are still removing them from Industrial sites, I got a really good shock off of one of these plugs, a few years ago, trying to unplug a motor in a glycol plant, in the freezing works, where I was working as an Electrician, good to see these old plugs banned.