Hi,

I am a graduate Electrical engineer, so i am lost. Here is the problem

I have a cable tray with armoured cables lying on it, these cables are of varying crossection and are touching |OooOoo| (Hopefully you can tell
--------
thats a cable tray with varying size and touching cables.)

I have been told by a contractor that the grouping factor need not be taken into account for the smaller cables, and that this is stated in the 17th Edition. So i have trawled throught the 17th edition and have not found this.

I have looked under section 523.5 and found the following statement:

'If due to known operating conditions, a non - sheathed or sheathed cable is expected to carry a current no greater than 30% of its grouped current-carrying capacity, it may be ignored for the purpose of obtaining the ratign factor for the rest of the group'

However in my case that current is approx 200amps, so i feel this is too big to be ignored. I know what your thinking ask him to indicate this, i have but am awaiting a response...... I would also like to find out through other means.

Also i have looked at Tables 4C1 i cant tell if the answer is there? If it is could you bring my attention to it please.

Regards,

ISA