interesting point, when the old sangamo weston mechanical meter was removed at my house, it was replaced by a new digital meter WITH A BUILT IN ISOLATOR!, when it went faulty a couple of years later it was replaced by another digi meter, without an isolator, when I asked the guy, he just said, "we're not fitting those any more". It was the same make, just minus isolator. When the original digi meter was fitted, I asked the DNO man what the difference in price was, he laughed and told me the old black mechanical meters were about £70 each, whereas the new ones cost..........................."about £11"! So the "cost to much" excuse is a bit invalid then?