Three phase and IBM

there are many, many, versions in serveal colours. This is what we used to call a 'BS4343' connecotr, and is sometimes known by the the trade name 'Commando' in the UK. Yellow 110V ones are common in 16A and 32A versions on industrial portable power tools over here (which as I mentioned a few months back are un off a 55-0-55V insolating transformer with the cnetre tap earthed). The blue 220V ones, in 16A and 32A versions are also quite common, I've also seen 63A and 125A ones. And red, 415V 3 phase ones are common in both 4 pin and 5 pin versions. There arel aosl other colours for 50V, etc, but those ae much less common. Sure. It is over here too. And if it's used, the neutral pin will be connected, so the wiring will be star (Wye). But I would not go so far as to claim that delta-connected 3 phasemains on the 4 pin socket never exists. -tony