Hello, I'm trying to find out what the current carrying capacity would have been for a 0.25inch paper wrapped multi-core cable buried in a trench. I think the early editions of the 14th edition Wiring Regs would over this, does anyone know what the capacity was, or where to locate this information? Thanks Adrian

Adrian
A 0.25 is the equivilent to a 150mm. It should do about 315A if buried.

Adrian

PM me your email address and I will send you the tables from a past regs. book.

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John Peckham

http://www.astutetechnicalservices.co.uk/

--i understand the 14th ed of the wiring regs quotes a rating of 375 amp
for 0.25 in defined conditions.

however the electricity board use a rating of 410 amp for this size cable.

Regards.

That's because you like to squeeze every last electron through it, 7671 tends to be a bit more conservative.

When you consider what you'll do with a bit of 95mm compared with what we can do with it our side of the meter, there's a little bit of a difference.


Stu

Generaly speaking DNO cables can be higher rated because the load is cyclic so the peak loads are only for a short time. Cables on the other side of the meter are rated for continuous use.
The DNO I worked for had primary transformers rated at 24MVA for domestic/commercial supplies but the same transformer would be rated 18MVA for supplying a continuous industrial load.