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Monday 5 August 2013

Don’t talk about the voltage.

Yesterday I wrote a pretty awful post about why I didn’t consider the government’s decision to encourage owners of diesel generators to prop up the National grid, in times of power shortage.

I spent most of that post banging on about frequency and load sharing. I should have added another factor  I think it’s a laughable idea.


In our houses in the UK the standard voltage used is 230V. This is a very low voltage in the great scheme of things but it is reasonably safe. If you touch an exposed wire it will make you remember it but unlikely to come to harm from it.

Not so the National Grid. This has sections that transmit at 400 kV (400,000 V). The simple reasoning is the formula taught in basic science classes. E=IR, where E is the voltage, I is current, and R is resistance. Even the best conductors in normal use today have their limitations. It would be infeasible to try and transfer electrical energy at household voltage. The cables would have to be huge in diameter. Therefore the high voltages.

Now in the  Hospital, public building, brothel, etc, it is not realistic to generate at those sort of voltages as there is only a very short transmission distance. Therefore it is most likely that they will generate at 440V(I’m going with my own experience here) for heavy power usage such as industrial heating systems and pumps. For general use it will be transformed down to 230V.

In short you have two totally incompatible voltages which you have to tie together with transformers and their losses, to make a back feed situation work.

Can it work? you tell me.

*Bought more candles*

I may post about the death and destruction that could be wrought.