Low Smoke & Fume cable versus P.V.C. cable overloading test. Shed Experiment.

Yes these demos are neither pure adiabatic, being far too slow - the heat clearly has time to get out of the copper into the plastic. (for be solidly adiabatic  kA and milliseconds are the right units) nor are they small overload of long  duration, which would be more like 40 A on a 2.5mm2 cable for an hour. In my limited experience of this sort of thing the 'cheese-wire" effect means that some form of ADS dead short detection operates before the cable actually flames.

However, as it is intended to illustrate the differnet performance of  low smoke cable it is still a nice demo.

Mike

Yes these demos are neither pure adiabatic, being far too slow - the heat clearly has time to get out of the copper into the plastic. (for be solidly adiabatic  kA and milliseconds are the right units) nor are they small overload of long  duration, which would be more like 40 A on a 2.5mm2 cable for an hour. In my limited experience of this sort of thing the 'cheese-wire" effect means that some form of ADS dead short detection operates before the cable actually flames.

However, as it is intended to illustrate the differnet performance of  low smoke cable it is still a nice demo.

Mike

P.S.C.C.s and earth fault currents around here will I believe be limited to a few hundred Amps according to my testing. Normally less than 1kA. But I suppose that nearer to substations the figure might be larger. And in towns and cities the figure nay approach a few kA.

Z.