What are the pros or cons of a 110-volt electricity supply against a 220-volt supply? | Notes and Qu

What are the pros or cons of a 110-volt electricity supply against a 220-volt supply?

• SUCH was the fear of the powers of electricity that when the first domestic supply system was being planned the authorities allowed only 100 volts with a margin of error of 10 percent. Such was the confidence of Eddison that he set it at 110 volts. Disadvantage: it takes longer to boil water in one's travel kettle.

  Peter May, St Albans, Herts (p.may@ukonline.co.uk)

• A 110-VOLT supply is less likely to electrocute you. A 220-volt supply can transmit the power more cheaply because a smaller current is needed, and so you can use thinner cables and/or lose less energy through heat generated in the cables.

  Ian McKay, University of Glasgow, (ian.c.mckay@clinmed.gla.ac.uk)

• TO ELABORATE on Ian McKay's answer, the current required for a given load power will halve with double the voltage. The power loss in the supply cables will quadruple with a doubling of the current. This is why power is transmitted about the land at 33,000 volts, to reduce the current in the wires and hence the power lost before it can reach the consumer. Try telling that to a water company with a 30% leakage rate.

  Mike Bond, Luton (m.a.bond@cranfield.ac.uk)

• IT'S A BALANCE between the cost of insulation and the cost of copper. At 110v, insulation requirements are much less, which makes possible the vast range of small, low-cost connector and switch gizmos available in the US. However, look at the mains cable on a big US appliance (such as a tumble drier) and you will see how much thicker is the copper in the cable to accommodate the higher current necessitated by the lower voltage. We 240v users gain in cable costs what we lose in connector costs.

  Paul Reilly, Tylers Green, UK (preil@hitachi-eu.com)

• Alternating current has the advantage that an energy efficient high distribution voltage can easily be stepped down to a relatively safe domestic voltage. Edison, however, insisted on sticking with his original direct current supply systems. Rumour has it that he invented the electric chair so that he could warn potential customers to steer clear - "You don't want that new-fangled alternating current, it's far too dangerous - it's what they use in the electric chair!"

  Jim Stacey, Crosby Merseyside UK