Nominal Voltage
- Thread starter New2Game
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U is the voltage phase to phase, which is 400V on a standard UK LV supply.
Uo is the nominal Phase Voltage (to earth for TN systems), which is 230V on a standard UK LV supply.
In reality the supply voltage will infact be more like 415/240V due to the nominal voltage having a tolerance of +10% / -6%
Uo is the nominal Phase Voltage (to earth for TN systems), which is 230V on a standard UK LV supply.
In reality the supply voltage will infact be more like 415/240V due to the nominal voltage having a tolerance of +10% / -6%
nominal voltage U is 400V..
Uo is 230V..
U is voltage phase to phase..
Uo is nominal voltage to earth ( for TN systems.. )
Uo is 230V..
U is voltage phase to phase..
Uo is nominal voltage to earth ( for TN systems.. )
In theory it was 240 which has been reduced to 230 to come in line with Europe which was 220 and is now supposedly also 230 or will be.
In reality, most of the time you will measure about 235. Does not matter in most cases as everything we have should work anywhere between about 200 and 250.
Calculations should be based on 230 unless specified otherwise.
In reality, most of the time you will measure about 235. Does not matter in most cases as everything we have should work anywhere between about 200 and 250.
Calculations should be based on 230 unless specified otherwise.
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Uoc is the open circuit voltage at the supply transformer (240v) which is used to calculate the maximum efli for a given protective device in the 16th edition of the regs, I was led to believe the 17th edition regs were going to drop Uoc to 230v, I'll check when mine turn up 
.
.
Have they still not turned up yet?
Got mine on wednesday
Got mine on wednesday
Remember the EEC Beef & Butter Mountains?
Electrically we had 415V phase to phase on 2 or 3 phase supplies and 240V between phase & N.
Then each factory donated 15V to make it 400V and each home donated 10V to make it 230V,
Stored in a big EEC Voltage mountain to sell cheaply to the Russians.
No only joking.
We simply redeclared the nominal voltages from 415 to 400 and from 240 to 230 and opened up the tolerances.
The rest of Europe did similar and then at "the stroke of a pen" we were all on the same voltage but not much actually changed in reality.
We are still (as yet) actually on the same voltage as we have been for years.
Taking it to a daft conclusion we might be able to redeclare again and make most of the world 1000V + or - 100% to consumers.
As fault currents are higher at 240 than 230 we have tended to use the higher figure for safety calculations but are changing towards the 230 figure now.
Electrically we had 415V phase to phase on 2 or 3 phase supplies and 240V between phase & N.
Then each factory donated 15V to make it 400V and each home donated 10V to make it 230V,
Stored in a big EEC Voltage mountain to sell cheaply to the Russians.
No only joking.
We simply redeclared the nominal voltages from 415 to 400 and from 240 to 230 and opened up the tolerances.
The rest of Europe did similar and then at "the stroke of a pen" we were all on the same voltage but not much actually changed in reality.
We are still (as yet) actually on the same voltage as we have been for years.
Taking it to a daft conclusion we might be able to redeclare again and make most of the world 1000V + or - 100% to consumers.
As fault currents are higher at 240 than 230 we have tended to use the higher figure for safety calculations but are changing towards the 230 figure now.
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