"...any Electrician worthy of the name would know..." Aw...steady on! [Linked Image]

Unless you are opening an accessory or looking at the conductors you can't see how many strands there are...

Personally I haven't been caught out yet, but I can quite see how someone trying to ID whether an isolated sample in a bundle is 4 mil or 6 mil might struggle; particularly as different manufacturers use differing thicknesses of outer sheath. I go with Paul here - a better indication on the sheath would not go amiss.

As for a quick ID - not always that easy.

If hindsight were foresight, we'd all be millionaires!