Power Cables Damaged by Heat. Canada.

The heat was undoubtedly exceptional with many records being broken.

However to to cause prompt cable failures seems a bit surprising unless the cables were already loaded beyond prudent design limits.

This is basically nonsense from the BBC to forward their agenda. The cable was obviously pulled hard against a thread, probably for years. It could have failed at any time. very poor workmanship- fail!

I thought loading beyond prudent design limits was normal practice.  You can get away with it if the high demand is due to a cold snap.

I thought loading beyond prudent design limits was normal practice

I think you will find in the case of DNOs and similar, that this is better described as  case of knowing quite well how much slack there is in the original design, or if you prefer, knowing what the assumptions were behind the headline ‘cable ratings’ including  how long things really take to get hot, and the degree  premature ageing from various degrees of running  over temperature, and then a cost benefit analysis.

It really is perfectly OK to load things to 200% of the steady state  rating so long as you do not do it for very long and co-ordinate protection to match.

The hot and cold weather de-ratings is a very good example of this.

The problem is that you cannot play the same trick for overloads due to  aircon in the summer.

Mike.

One of the problems with overhead cables in extreme weather is that they can expand and sag to the point where they no longer meet the clearance requirements

Looks to me as if the bolt got hot enough to melt the insulation?