How can a 120 V 60 Hz incandescent bulb fixture work in a 230 V 50 Hz outlet?

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    \$\begingroup\$ If you are talking about just the fitting you should not have a problem but you need to put a 240V bulb in it. \$\endgroup\$ – RoyC Dec 23 '16 at 12:58

The FIXTURE does not care what is the voltage or frequency. But if you put a 120V BULB in a fixture connected to 230V, the bulb will burn out from 2x over-voltage.

The question as stated is too simple and obvious. Perhaps we are all missing exactly what you are asking for?


Incandescent bulbs are basically just a wire heated to a point where it glows. So you could also just represent it as a resistor. Therefore, if you change the supply from 120V/60Hz to 230V/50Hz, the power output will be greater. Please note that frequency difference has no effect on a resistor. The lightbulb will work, but most likely only for a short period of time. The greater current will burn it out much, much faster.

Your question could also mean "How can I make a 120V/60Hz work with 230V/50Hz supply?" In that case, you would need to reduce the current flowing through the lightbulb. Simplest way is adding a resistor, more complex would be using PWM.

  • \$\begingroup\$ With incandescent bulbs you also have to take the effect of the temperature on their resistance into account, the operating resistance is a lot higher than the cold resistance. This means that putting a 230V into a 120V bulb won't result in double the current, the actual increase will be less than that. It's still not going to last long assuming it doesn't blow instantly but it's not quite as simple as a straight Ohms law calculation. \$\endgroup\$ – Andrew Dec 23 '16 at 12:48
  • \$\begingroup\$ No, simplest way is Roy C's suggestion - replace the bulb(s) in the fixture with 240 volt bulbs. If that's not possible, wire two fixtures in series (although that will violate code). If that's not possible, THEN you start adding resistors, but the power dissipation required poses a real fire hazard unless you really know what you're doing. \$\endgroup\$ – WhatRoughBeast Dec 23 '16 at 13:06
  • \$\begingroup\$ Yeah, obviously I would recommend using the right lightbulb, it is just that the question was really ambiguous. \$\endgroup\$ – slavko vujinovic Dec 23 '16 at 13:11
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    \$\begingroup\$ Guys. When answering these questions you need to take into account of the level of knowledge being shown by the OP. While technically correct I would respectfully suggest that recommending adding resistors is dangerous. \$\endgroup\$ – RoyC Dec 23 '16 at 13:43

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