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Posted By Topic: aerial conductor current rating

Oct 16 2019 23:43

Hi, just doing some work in auckland city grey lynn on an old villa which is rare for me and I noticed the aerial conductor looks smaller than usual, possibly 6mm.

Anyone have experience on this type of conductor? whats the current capability?

Thanks in advance.


Oct 16 2019 23:48

3008.1.2 table 20

Oct 17 2019 10:25

typically most old houses had a 6 mm (equivalent imperial) cable and the houses had a 32 amp supply. Over time some of the linesmen changed the fuses to 60 amp. Old houses used to have gas ovens and very little number of socket outlets and load. Now most houses have increased their load to the point that the old 6mm cable should be replaced.

Oct 17 2019 11:49

If a Max demand assessment indicates the cable can carry the MD, then all that's needed is to provide overload protection for the mains
(something networks don't have to provide under ESR 32).
Lots of houses can sit happily on a 32 A supply. And in some areas you can get a lower fixed charge by using an mcb as a current-limiter.


Oct 17 2019 14:42

And I can remember the days when the house mains were 7/029 with a 60amp pole fuse, electric hot water, range etc etc, no smoke!

Oct 17 2019 15:33

And that would have often been a bit of 60 A fusewire; ie "coarse protection" that would take more than 4 h to blow even with a 50 % overload (90 A).

Not good enough under today's rules, but ESR 113 says it can still remain in service.

I remember the first time I installed a current-limiter - 3-phase 32 A for a commercial installation - and the local network reckoned that the handle of the mcb had to be sealed as well as the terminals. Their "thinking" was that it was similar to a pole fuse, and so only their staff should be able to reset the mcb. Took a couple of weeks before they accepted that since the owner paid for it, the owner could damn well reset it if it ever tripped (which it hasn't in approx 20 years); and get back to work instead of waiting for a faultman.


Oct 17 2019 17:26

Those were the days, sigh!