I think a lot of people don't realise there's different choc block connectors for different applications. You get the cheap ones which are usually some sort of polypropylene or even polyethylene, they're the type mentioned above that turn to powder over several years if they're in a warm environment like in a light fitting snuggled next to the ballast.

You also get Nylon connector blocks that look pretty similar to the cheap polypropylene but they're far less flexible, in fact you can't twist a strip by hand to break them off if they're nylon. The nylon connector blocks don't disintegrate over time because they're rated to 125 degrees celsius and also have higher current carrying capacity because of their temperature rating.

You get the standard polypropylene and also the Nylon connector blocks where the screw tightens directly onto the wire but there's better connectors available in both materials that have a tongue type wire guard inside them that are supposed to be used for stranded conductors. You also get connector strips that have a full cage type termination inside them similar to the type found in most circuit breakers.