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domestic microwaves on boats

I have been using a domestic microwave on board the boat, but it's just been diagnosed as beyond economic repair.It was only just over 2 years old and was a decent brand. Is this related to the damp atmosphere or have I just been unlucky ? I would prefer to use a domestic micro to a specialist one but not if I have to replace it every 2 years.

Asked by: Sue Harding Hirst  | 2.57pm, Wednesday 29 July

WW says:

You may have been unlucky, or the problem may lie with the inverter. Microwave ovens are rated on their power output but their input requirements are usually about twice this. A microwave rated at 800 Watts therefore needs about 1,600 Watts to drive it. If your inverter has not been supplying quite enough power, it may have caused parts of the microwave to overheat and fail prematurely.
Alternatively, it could be the quality of the power your inverter is supplying. Microwaves normally run on mains electricity which undulates in a smooth '€˜sine-- wave form. They will usually work with a quasi sine wave provided it is fairly near to a sine wave and not too jagged. Some older, less expensive ones have wave forms that are not much better than square wave.
Buying a --12-volt-- microwave might solve the problem but, as well as being more expensive, it could have other drawbacks as well. Most of these microwaves are 230-volt units with an inverter built in and, even if they are not, the cables between them and the battery bank are still carrying a hefty current at 12-volts. Assuming that the galley is well forward of the engine room, this means that the cables need to be incredibly thick to carry the current over that distance. The more usual solution of having the inverter near the batteries means that the cables connecting them can be of a reasonable size and the cables from the inverter to the microwave can also be of normal thickness as they are at 230-volts.
Buying a new microwave and a better inverter may seem an expensive answer to the problem but it may pay dividends in the long run.

Graham Booth  | 10.14AM, Friday 31 July

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