Electricity Mains

[o_total]

Seems as though this thread was started back in 2006 and is still being disputed 2 years later, and without a peep out of the original poster. LOL.

Ahh well.

I guess it depends what he means by mains. Does he mean service mains, consumers mains, sub-mains........???? guess he is not here to answer that question.

All new services within the Energy Australia area, Newcastle, Central Coast and Sydney are 25mm which is good for 100amps, which is more than ample for the average household, and whats more if you want more than that then you just add 2 more phases giving you 300amps (3 x 100amp)if thats what you require.

Hope this helps someone.

LOL
Brett

[dan76]

all the figures here seem to be quoting optimal installation scenario. if your mains run through your roof and insulation 16mm is only god for 57amps clipped to a truss and 36 amps completely surrounded.
a long way from 80 amps lol
16mm is good for 91 amps in conduit underground, but if your conduit goes up a wall that cuts it down to 71 amps.
also if you have 3 phase mains bundled going trough insulation in your roof 16mm is rated at 36 amps completely surrounded and 52 amps clipped to a beam.
figures from table 3 and 6 of as3008.1.1 1998

[Smurf]

Also in all my years as a Sparkie Ive never seen 4mm2 Mains
Nor have I seen 25mm2 Mains in a domestic environment.

Only time I've seen 4mm mains is for traffic lights, electric fences and other small, steady loads like that.

But in Tas at least they don't allow less than 6mm now even for those type of installations. It relates partly to the mechanical strength of the cable running through numerous pits etc as a number of failres have occurred where the cable simply subject to too much mechanical stress and eventually failed.

In Tas heating systems (including but not limited to air-con) are metered separately from everything else (domestic only) which overcomes the 100A meter limit where it's an issue. This is a separate heating tariff (cheaper than the light & power rate) available 24/7/365 and not a time of use or off-peak rate.

Most houses here would have 1 meter for the light & power and at least one other meter (sometimes 2 others) for heating and/or off-peak. Hence no problem going over 100A on single phase supply as long as it's due to heating or air-conditioning.

I'm told there is one Victorian power distributor that will meter air-con separately if it's reverse cycle and meets specified requirements. The incentive to do so is a cheaper rate for power used during winter - hence must be reverse cycle. Not sure if that is still done however.

Only downside can be having to accommodate 3 meters plus a time switch for off-peak on a domestic switchboard - many aren't big enough. Most get around it by just not having off-peak but there's a new 2 tariff meter + time switch unit available that is the same physical size as one conventional meter. That fixes the problem in 99.9% of cases.