I've just come across a 50-ish-year old ring circuit where one cable at the CU is the usual 7/0.029" red/unsheathed/black Imperial T&E cable, but the other cable is red/transparent/blue, all three conductors (apparently) 7/0.029". I've never seen this cable type before - is anyone familiar with it, and if so, what's its story?
For 3 phase without neutral or earth, in the days before earthing was what it is today, red white and blue would be power. The thing at the end of it would be what we now call class 0I (or in some older text 0A) and earthed via another route such as cable ducting or pipework.
Not allowed any more, but quite common in 1960 (not much before that or it would have been rubber).
Used like this with the second phase core as a full cross section earth is perfectly fine. I suppose you could feel the urge to add green yellow sleeving, I'd leave it, unless it is damaged in some way, its probably good for another 50 years if it keeps out of the heat and the sun.
For 3 phase without neutral or earth, in the days before earthing was what it is today, red white and blue would be power. The thing at the end of it would be what we now call class 0I (or in some older text 0A) and earthed via another route such as cable ducting or pipework.
Not allowed any more, but quite common in 1960 (not much before that or it would have been rubber).
Used like this with the second phase core as a full cross section earth is perfectly fine. I suppose you could feel the urge to add green yellow sleeving, I'd leave it, unless it is damaged in some way, its probably good for another 50 years if it keeps out of the heat and the sun.
