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16mm swa buried is only 78 amps ambient temperature 20 degrees and that's without applying the 0.9 correction factor as cable is buried for ambient temperature for 30 degrees plus any other factors like depth etc
 
I always opt for the three phase rating with a three core but that is another debate but yes either way it is undersized if you use 16.0
 
16mm swa buried is only 78 amps ambient temperature 20 degrees and that's without applying the 0.9 correction factor as cable is buried for ambient temperature for 30 degrees plus any other factors like depth etc
Just trying understand - Table 4D4A for direct buried at 0.7m, ambient 30, ground ambient 20 and conductor 70 is 78A. So question is, why pick 30 ground temp to further derate to?
 
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Just trying understand - Table 4D4A for direct buried at 0.7m, ambient 30, ground ambient 20 and conductor 70 is 78A. So question is, why pick 30 to derate to?
0.9 is applied where overload protection is required and prevents the cable going over temperature when overloaded.
The factor is used because cable ratings for cables in the ground are based on a ground temperature of 20 degrees compared with 30 degrees for other reference methods.
See regulation 433.1.203
 
which is all wrong. rarely will the ambient temperature rise above 20dg. C. in this country. once you are down 2 ft. underground the temp. is down to around 10dg.C.
 
IET Forums - Underground SWA Current Rating? - http://www.------.org/forums/forum/messageview.cfm?catid=205&threadid=27920
 
as an experiment, try shoving 100A down some 16mm for an hour. then measure the temp. of the cable. if you read >40deg.C. then your temp gauge is wrong. :eek:
 
we not in the sahara . not even spain. 30deg. my arse. we'd all be like essex boys at that temp. but with real tans.
 
haha, trouble is that the regs. are so pessimistic. written to cover arses. as a famous person once said." rules are for the strict adherence of fools, and for the guidance of wise men"
 

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