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Joined: Mar 2015
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I see now if you have 3 phase available as long as you don't put the oven on the same phase as the shower it works fine. I think you might have to get the poco to uprate your supply otherwise I think you will need to get a decent supply of candles in I really can't understand why European countries don't to the same as the UK and have an 80 or 100 amp supply to a house there's never any overload issues unless you live at the end of a very long line and that's rare

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Originally Posted by annemarie1
I see now if you have 3 phase available as long as you don't put the oven on the same phase as the shower it works fine. I think you might have to get the poco to uprate your supply otherwise I think you will need to get a decent supply of candles in I really can't understand why European countries don't to the same as the UK and have an 80 or 100 amp supply to a house there's never any overload issues unless you live at the end of a very long line and that's rare

Over here in NZ, AnnMarie, stoves out in the country were fed with 2 phase 400V, mainly to make sure that when you turned the grill element on, it wouldn't knock half the house out during winter.

I personally think that fusing a 240V house at 80 or 100A is out-landish, sure the houses are possibly bigger over there, but I'd struggle to name any house here that has anything more than a 63A single-phase fuse feeding it, let alone 100A.

You mention about being at the end of a spur-line, it is up to the local supply authority to provide either a tap-changer transformer (that changes the voltage when the load on it increases) or a higher HV voltage into your EOL transformer to take voltage drop into account.

Joined: Dec 2001
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Large supplies are really unnecessary unless you run a bunch of electric showers and other huge loads. Cookers and hobs have the option of connecting them to 3 (cookers) or 2 phases (most hobs), as do all larger electric water heaters and instant showers. I've heard of people who successfully managed to live with a 25 A 3-phase supply, a free-standing electric cooker and a 21 kW electric shower without ever blowing a main fuse! That's an extreme case and it was probably sheer luck for them but 35 A 3-phase already provides a lot of power. If you've got a gas cooker/hob and a combi boiler or central heat and hot water you're extremely unlikely to exceed a total load of 5 kW in my experience!

Joined: Mar 2015
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To Trumpy: I think I said that our highest total load never exceeds about 40 amps there are usually 2 of us in the house and that load is only if one of us is showering and the ovens on and a few lights and other small items so yes we could live with a 63 amp feed however if we had a full size family with several people all with TVs and lighting on it might be pushing it.AutoTap changing is normally only on the 33/11 Kv tranny the local poletop trannys out in the sticks are usually offload changing by manual switches maybe NZ practice is alittle different. Whatever system you got as long as it works it don't matter if its 3 or 1 phase.

Joined: Sep 2011
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240/415Y 60Hz would be the global standard in an ideal world, unfortunately we seem to be using less premium combinations.

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Originally Posted by Trumpy
Originally Posted by annemarie1
I see now if you have 3 phase available as long as you don't put the oven on the same phase as the shower it works fine. I think you might have to get the poco to uprate your supply otherwise I think you will need to get a decent supply of candles in I really can't understand why European countries don't to the same as the UK and have an 80 or 100 amp supply to a house there's never any overload issues unless you live at the end of a very long line and that's rare

Over here in NZ, AnnMarie, stoves out in the country were fed with 2 phase 400V, mainly to make sure that when you turned the grill element on, it wouldn't knock half the house out during winter.

I personally think that fusing a 240V house at 80 or 100A is out-landish, sure the houses are possibly bigger over there, but I'd struggle to name any house here that has anything more than a 63A single-phase fuse feeding it, let alone 100A.

You mention about being at the end of a spur-line, it is up to the local supply authority to provide either a tap-changer transformer (that changes the voltage when the load on it increases) or a higher HV voltage into your EOL transformer to take voltage drop into account.


Here in the US half of new homes are fused at 200amps, even the small 1,200 foot homes.

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Here in Norway the common voltage are 230 at 50Hz single or 3-phase supplied from a delta wound transformer, that makes it without neutral. The line between the last house, and the transformer may sometimes be more than 1000 meters (=yds?) The older houses usually have small fuses, maybe only 25A single phase at 1000 sq feet.

A completely new system would have 230/400V with a neutral. (if the not connected to an old supply of 3*230V) Usually all houses has 3 phase (apartments: single phase) and the the system should be designed to be able to carry a load 10/6 of the calculated need.

This thread started with why 230V at 60 Hz, The chosen 50Hz in Norway today is based on what the neighbors use, but long time before we connected the countries together, 50 Hz was not flickering, but the lower frequency, the lower loss on long lines. Svalbard used 25Hz for a while, Halden used 40Hz, but thats all history.

I wonder about what the standard would have been if we started on today. What about 500V at 400hz in the local system and a DC high voltage grid?

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We did a lot of 400 hz in computer rooms and that comes with it's own problems. To start with you really start needing very finely stranded wire because the current is starting to be a skin thing and not flowing through the center of the conductor. The main advantage is smaller transformers. I suppose motors could be smaller too because they used 400 hz for naval servo systems and that was the main reason there.
Why North America chose 60hz and Europe chose 50, I can't answer but the center tapped single phase (120/240) was seen as a safety thing when Westinghouse and Edison were fighting over AC v DC. In those days it was really more like 110/220. These days most motor driven stuff really struggles at 110 v and likes 120 a whole lot better..


Greg Fretwell
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I suspect 50 vs. 60 Hz is mainly related to decimal vs. pre-decimal (multiples of 6) thinking and derived from the generator RPMs. A two-pole 50 Hz generator runs at 3000 RPM, a 60 Hz one at 3600. Europe was already pretty much metric and decimal by the time electricity came around, except for the UK.

Was the 120/240 V 1-phase developed alongside Edisons 3-wire DC? It'd seem more logical that it was a reaction and an attempt to use existing DC mains and existing equipment (anything that'd run on both DC and AC) during the conversion from DC to AC, at least to me. That's just an educated guess though. The only thing I do know is that all mains voltages in the world were likely derived from the operating voltage of series-wired arc lights, i.e. multiples of 50-60 V.

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Edison, who was more of a marketeer than a scientist saw DC as a system that would involve lots of generators spread across the city, all sold by him. Tesla and Westinghouse envisioned the grid and a few very large generation facilities providing power to a wide area of customers, using transformers they sold. Tesla even dabbled with the idea of transmitting power over the air.
They were both advancing their plans at roughly the same time though. (1880s)
I don't think there were any large scale DC distribution networks but Edison did sell a lot of generators for individual mansions, offices and factories.
By the time large scale distribution systems came online, AC had won the fight.


Greg Fretwell
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