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Mains Power Curiosity?

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I think Nigel is asleep, so I will pick up on this.

Is all of the 3 phase power available in the uk is all Delta wired?
No. At street level, the distribution is 400/415volt 3phase, star connected with a neutral.
The neutral is earthed, so you get 230/240v single phase from each line to neutral, this is what is fed into domestic premises, and 400/415 volts 3 phase between lines which is fed into commercial premises.

Do you have the wierd 277 V that the US has for lighting?
No.

The US distributes 3 phase Y and 3 phase (HI Delta). Because of that industril might have 240 3 phase, 208 3 phase, 240 single phase, 208 single phase and 120 single phase. Then there are other varients such as 460 and 480 VAC for higher power loads.
We just have 400v 3phase star + neutral.

At higher levels in the distribution system, the voltages are 3.3kV, 11kV, 33kV, 132kV, 275kV and 400kV.
How these are connected I dont know, that is way beyond my experience.
For the lower voltages, there are usually just 3 wires on the tower.
For the higher voltages above 132kV, there are six wires which I believe are two separate 3phase circuits. There is also an earth wire at the top of the tower presumably for lightning protection.


As an additional point, for many years the official supply voltage in the UK was 240v (415v 3phase).

As part of European standardisation, the official supply voltage is now 230v (400v 3phase).

The voltage which appears out of the socket on the wall is still 240v because 240v is within the tolerance defined for the Euro 230v supply.

JimB
 
I know that 120V can kill you if you are also touching a solid ground, especially if it also involves water, but I guess if you are connected to a solid ground then you are fried either way and if not, then you will likely survive. The in-between situation where you have a sufficient ground resistance to kill you with 240V but not with 120V is probable rare.

I do like the idea of 240V for house wiring since it obviously reduces the amount of copper required by half for a given power. Do you know what the standard wire gauge is used for house wiring in the UK?

Mains sockets are wired using 2.5mm T&E in 'ring mains' - usually you have separate rings per floor.

Lighting uses 1mm cabling, on separate circuits to the power.

For cookers or showers, you use thicker cable direct from the fusebox, 4mm, 6mm, or 10mm.
 
At higher levels in the distribution system, the voltages are 3.3kV, 11kV, 33kV, 132kV, 275kV and 400kV.
How these are connected I dont know, that is way beyond my experience.

Our recent power cut at work (as far as I know we're still running on generators?) was due to a major explosion in the 33kV building at the sub-station.
 
At higher levels in the distribution system, the voltages are 3.3kV, 11kV, 33kV, 132kV, 275kV and 400kV.
How these are connected I dont know, that is way beyond my experience.

In my limited experience, 3.3 kV and 11 kV loads in industry are invariably 3 phase, with no neutral.

Where I used to work, the larger motors, above 1/2 MW, would be 3.3 kV, or in one case 11 kV. The ring main around the plant was at 11 kV, so the company I worked for, rather than the electricity supply company, owned all the 11 kV / 3.3 kV or 11 kV / 415 V transformers.
 
In my limited experience, 3.3 kV and 11 kV loads in industry are invariably 3 phase, with no neutral.

Where I used to work, the larger motors, above 1/2 MW, would be 3.3 kV, or in one case 11 kV. The ring main around the plant was at 11 kV, so the company I worked for, rather than the electricity supply company, owned all the 11 kV / 3.3 kV or 11 kV / 415 V transformers.

For those who remember the miners strike? (early 80's) a large number of pits closed shortly afterwards.

At a pit not too far from me a couple of the laid off workers pooled their redundancy money and bought the entire scrap rights to the service of the pit.

They did this for a couple of reasons, firstly because there was a LOT of equipment there they could sell, but more importantly (and they knew this) there were two brand new and still crated sub-station transformers amongst the equipment. Either of these was worth more than they paid for the scrap rights :p
 
In rural NZ there is split phase in use at 230 / 460 Volts or 240 / 480 Volts usually centre tapped 230 - 0 - 230 Volts or (240-0-240)

The phasing is 180° apart instead of the usual 120° from common three phase.
 
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