Discuss Suggestions for best way to wire underground supply please in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net
That part would be ok - 89A clipped direct or 97A in free air ?What about the part of the cable that comes out of the ground?
Based on 30 degrees tho yes?That part would be ok - 89A clipped direct or 97A in free air ?
Only if you pay my electric billas 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.
Well it errs on the side of safety but I didn't write the regs , send any complaints to jpel/64 hawe not in the sahara . not even spain. 30deg. my arse. we'd all be like essex boys at that temp.
Yes, 4D4A is for ambient air temp of 30. Still thinking ...Based on 30 degrees tho yes?
The overall ccc of the cable needs to be the lowest rating if installed using different reference methods using the most onerous methodYes, 4D4A is for ambient air temp of 30. So for cable in free air Ref E - well the cable isn't buried any more - so 433.1.203 doesn't apply and that part of the cable doesn't need derating from what's listed in the table ?
I would assume tests would have been performed and the appropriate ccc recorded as we see them today.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"
Don't thank me yet wilko as someone might come along and shoot me down in flames.Got it - thanks Ian
Ha ha, always on the cards !Don't thank me yet wilko as someone might come along and shoot me down in flames.
It's how I understand it and it's written in be 7671 so got to go with that don't we?
Have a read of guidance note 6.Ha ha, always on the cards !
I needed to re read 433.1.203 a few times. Using an 80A fuse for overcurrent protection of a buried cable then the cable needs to be rated >=89A and clearly 16mm isn't when it's buried
Good thought - I've 1, 3 and 8 now I've a reason for 6Have a read of guidance note 6.
A lot more clear on the subject.
IET Guidance notes are our friends
I'm the same except my 3 is to the green version of bs 7671 and only bought it for my testing exam.Good thought - I've 1, 3 and 8 now I've a reason for 6
It's ability to dissipate heat is worse when it's buried would be my guess, especially if installed in a pvc duct.Why would buried in the ground be considered more onerous for current rating than clipped direct/'free air' . Doesn't make sense to me.
I know what you mean! Looking into it a bit (feedback appreciated)Why would buried in the ground be considered more onerous for current rating than clipped direct/'free air' . Doesn't make sense to me.
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