Twilight zone

SIR – As a registered visually disabled person, the quality of domestic lighting is crucial to me.

Scottish Power has run checks on our supply. It is inside the parameters which they have to maintain, but they do not tell you that they are free to vary it. In our experience, it is a minimum of 238 volts on average every fourth day, and a maximum of 252 volts. This is a massive difference, particularly during the darker days.

For some reason they will not admit that it happens. The other day I did not have enough light to write this letter. Yet now I am floodlit. Why? We are close to the a huge wind farm in Liverpool Bay. David Bollans

Heswall, Wirral