The MV->LV transformer in your street still makes three phase power. You then split it between houses so that roughly a third of the houses (and street lights!) are on each phase.
Andre’s situation involves 12 houses sharing a supply, if I understand correctly, so I would expect roughly 4 houses to a phase.
Indeed! The house I had in one of the old suburbs of Joburg shared 3 phase supply with 2 phases being fed to each house and the 3rd phase used for street lights. I don’t know how well this was balanced..
The neutral still makes me worry. With the testing I never saw that problem, but I was busy fault finding in my unit. We have a three phase supply into our main distribution board inside the complex, with the phases split between the different units. It all makes sense, but I will also start with the MDB to see how the earth’s are connected there and then in my unit too. I believe we have had a electrician looking at the problem and will be back. With the new municipal structures, that scares me even more. But thank you for all the suggestions. My career was on communications, starting with the old valve jobs, then UHF multichannel radios and lastly digital microwave. I have retired but still have a interest in electrical problems. Some jobs being done here scares me!
Voltage regulators like this provide peace of mind:https://www.facebook.com/marketplace/item/1428464691703045
They monitor the mains voltage and have indication of any alarms if things aren’t ok.
That’s the situation in my street. One phase feeds one end of the street, another phase feeds my end of the street, the third phase powers the street lights. It’s hard to see how this can be a balanced situation.
Or so it’s said.
Sometimes after load shedding we would have one end of the street with power but not the other. Which suggests that one phase had tripped or was never restored.
So am I right that you can have just two phases actually connected?
In Johannesburg there are tariffs for 3-phase domestic supply, and they have 3-phase pre-paid meters. I would think that this is partly because houses were built with a 3-phase supply and unless all those properties are converted to single phase, the City has to keep on servicing them.
And as @plonkster points out, there is often a 3 phase supply down to where the LV supply emerges from sub stations.
When I mentioned neutral I was thinking of a case in our street where the downcable from one pole was stolen and then replace. The pole provided power for three houses. The guys who repaired did something they shouldn’t have when reconnecting the neutral (or not reconnecting), and those three houses had a torrid week.
I also just heard a tale from a city councillor about a scam where contractors sent out to fix this kind of outage draw copper cable from the store, sell the copper, buy the aluminium cable used for the aerial part of the feed and use that instead. Which creates problems because … something that he doesn’t understand because he’s a councillor, not an electrician. Apparently the aliyumyum cable can only be used between poles.
Yes you can as long as the neutral is also connected. I think the safest and simplest distribution is single phase to each house. If more power is required then a three phase supply should be installed. This nonsense like I had with two phases and a neutral is confused. My guess the reason for this was that a single phase supply wasn’t enough power for the houses on an acre in the northern suburbs of Joburg (with tennis court, pool and who knows what). Those were the days!
Believe it or not we bought this rundown house when it had fallen out favour and so it was good value. One had to subdivide the property to show a profit when selling. No one wants such a big property these days.
I’ve seen this in other parts of the world. Canada, to be exact, on a support case. It was a commercial area rather than residential, so they had three phase in the area instead of the usual single phase with the neutral in the middle, aka split phase. This particular shop had a two phase supply, 120 degrees between the phases, 208V across the phases (instead of the usual 240V you get in North America) and the usual 120V to neutral.
I believe it is also common in NZ, three phase distribution in the street, houses normally get single phase, but if you need more you can get another phase, leaving you with a two-out-of-three setup.