A debate on another forum has prompted me to ask why there is common reference in the regulations to limiting the length of a cable to 3m to satisfy certain conditions. There are some clever people on here so hopefully I will learn. I will give some examples to illustrate the point of my question.
433.2.2 (ii) Its length does not exceed 3 m,........
434.2.1 (i) not exceed 3 m in length, and
Limiting the length of a cable to 3 m does what exacly? Why 3 m? Why not 5 m?
I am a logical kind of person. I look at rules and like to understand the reason for them. In this case I just cannot. It comes over as a notional length picked by the IEE at random when writing the regs. Don't get me wrong, I can see that limiting a cable length will fix voltage drop, fix resistance/impedance over that length, but I just do not understand why 3 m?
Some background to the question. The debate that was discussed on the the part of one poster decreed that this 'rule' applied to unfused spurs off a ring final circuit. Several posters, including me, said that the 3 m rule did not apply to unfused spurs off a ring.
Thank you.
433.2.2 (ii) Its length does not exceed 3 m,........
434.2.1 (i) not exceed 3 m in length, and
Limiting the length of a cable to 3 m does what exacly? Why 3 m? Why not 5 m?
I am a logical kind of person. I look at rules and like to understand the reason for them. In this case I just cannot. It comes over as a notional length picked by the IEE at random when writing the regs. Don't get me wrong, I can see that limiting a cable length will fix voltage drop, fix resistance/impedance over that length, but I just do not understand why 3 m?
Some background to the question. The debate that was discussed on the the part of one poster decreed that this 'rule' applied to unfused spurs off a ring final circuit. Several posters, including me, said that the 3 m rule did not apply to unfused spurs off a ring.
Thank you.