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I was checking out my Moulinex electric sandwich maker recently and a question popped into my head. On the reverse side of the maker it says that it takes as input 220-240 volts at 50-60 Hz and it's power consumption is 700 watts. From what I know about electricity this tells me that the current flowing through this device is 700/~220 = 3.18 amperes.

Now this is kind of surprising, since the way I understand sandwich makers work, is they take a current and essentially drive it through a piece of high resistance alloy. Now shouldn't this high resistance material drop the current in the whole circuit? It certainly can't be as high as 3.18 amperes.

JRE
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goose
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2 Answers2

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The current when it is heating will be about 3A. There may be a thermostat that cuts it off before it overheats (thus maintaining a reasonable cooking temperature), but when it is heating the current will be about 3A with the nominal 230V line voltage.

The resistivity of the (probably) Nichrome (80% Nickel- 20% Chromium alloy) heater windings is much, much higher than copper or aluminum, and they are long and thin rather than thick, which is why the wires in the line cord do not get noticeably warm, but the sandwich maker surfaces get too hot to touch.

Spehro Pefhany
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Moulinex have decided that 700W is what you need to toast a sandwich (and who am I to say otherwise) and so from a 220V supply that requires that 3.18A be drawn, and so a resistance of around 70 ohms is required. Whether a short length of high-resistance wire or a long piece of lower-resistance wire has been selected, the effect will be the same. If the current were dropped lower than this then the desired heating effect would be reduced.

Frog
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