What will happen if you plug in a heater 120 volts to 240 volts?

Answer 1

You will not pull enough power to properly operate the appliance, and you can damage the electric assembly possibly nullifying the warranty. It won't work very well. You need to get a 220 breaker, which goes across both legs of the 220 panel as opposed to a 110 v breaker which only pulls current from ONE leg of the 220 line. But it won't burn out anything if you only connect it to 110.

Answer 2

If it's a true 120 V only appliance, and not a dual-use appliance it will most likely break immediately. There may be a fuse in the unit, which can be replaced the unit to get it working(with the right voltage) again, or the unit may be permanently destroyed.

Answer 3

208 volt heater on 240 volts

The heater will operate over its given specified wattage. A 208 volt heater run off of 240 volt will have an output increase. Ohms law stated that current is directly proportional to the applied voltage and inversely proportional to the resistance of the circuit. A 240 volt heater can be run off of 208 but the wattage will be reduced.

For example if the heater is 5000 watts at 208 volts, the current is I = W/E 5000/208 = 24 amps. The resistance of the heater is R = W/I (squared) = 5000/24 x 24 (576) = 8.68 ohms. Applying 240 volts on the same heater whose resistance is 8.68 ohms results in this new heater wattage rating. W = E (squared)/R = 240 x 240 (57600)/8.68 = 6636 watts. This is 1636 watts higher than the manufacturer's safety rating.

W = watts, I = amperage, R = resistance in ohms and E = voltage.

Answer 4

If the supply is well protected , the circuit breaker will trip. If your wiring is old & of poor insulation , there could be an electrical fire somewhere in the wiring. assuming that the power wires & the supply outlet are capable of handling the power drawn & the heater is robust enough it will run for some time at double its rated capacity .

However since the temperatures will be considerably higher than normal operation, the weakest or the hottest part on the heater will burn out akin to a fuse. The cheaper the heater the faster the burnout time, which could be for practical purposes almost instantaneous.

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120 volt heater on 240 volts

The heater will operate over its given specified wattage. A 120 volt heater run off of 240 volt will have an output increase. Ohms law stated that current is directly proportional to the applied voltage and inversely proportional to the resistance of the circuit. A 240 volt heater can be run off of 120 volts but the wattage will be reduced.

For example if an ordinary 1000 watt baseboard heater's supply is 120 volts, the current of the heater will be, I = W/E 1000/120 = 8.3 amps.

The resistance of the heater is R = W/I (squared) =1000/8.3 x 8.3 (69) = 14.5 ohms.

Applying 240 volts on the same heater whose resistance is 14.5 ohms results in a new heater wattage rating. W = E (squared)/R = 240 x 240 (57600)/14.5 = 3972 watts.

This is 2972 watts, almost 300%, higher than the manufacturer's designed safety rating.

The amperage drawn by connecting a 120 volt, 1000 watt heater to a 240 volt source will be, I = W/E = 3972/120 = 33 amps.

W = watts, I = amperage, R = resistance in ohms and E = voltage.

Answer 5

It gets hot very quickly. If the internal thermal protection device doesn't trip then most likely the breaker will. e.g. 1000 watt heater. Normal current for the heater at 120 volts is 8.3 amps. To find the resistance of this heater use the formula R = E sq/W. 120 x 120/1000 = 14.4 ohms resistance. Now for the current at 240 volts, I = E/R. I = 240/14.4 = 16.6 amps. As you can see you will be introducing double the current to the 120 volt heater. Ohms law states, the current is directly proportional to the applied EMF (voltage) and inversely proportional to the resistance of the circuit.

Answer 6

All those answers that use a static resistance value are incorrect. A heating element starts with a low resistance and the resistance increases as the element heats up. With the higher voltage applied the resistance increases to the point where the rated heater output is obtained. It then is self limiting due to the increasing resistance with temperature increases. The heating element composition, length, and surrounding cooling forces, will determine the effective resistance of the element with a specific applied voltage. This will not be as hot with a lower voltage but the actual temperature is typically not a linear function.