Letter: High voltage

From Dr T J Dennis

Sir: Arthur Tarrant (letter, 19 February) is correct when he remarks that a colour TV set contains components that operate at 25,000 volts, which is the same as the voltage used on the overhead supply for railways. The crucial difference, however, is that in the TV the voltage is at DC, while the rail supply is AC; and the problem with leukaemia is claimed to be due to alternating magnetic fields. These will be present near any exposed cable carrying a large alternating current.

Yours sincerely,

Tim Dennis

Birch, Colchester