A 100 watt bulb draws 100 watts at 110v. Wattage = voltage x amperage. Double the voltage, you double the wattage. I think the bulb would blow, perhaps violently. Or maybe the switch you are turning. Either way, not a good thing.

If lamp cord is rated at 300v, I think putting 220v though it is getting too close.

A plain old floor lamp would not cost too much to rewire. If you are handy and can put your hands on the proper parts it could be a good do it yourself.

Otherwise, I'd use a transformer.

Electricity can be pretty unforgiving.

Are you heading to the UK? If so, I can put you in touch with a company I know who will be able to help you out.

While living in Italy I used American made lamps without any problem - just have to remember to switch out the 110 bulbs for 220 bulbs :)

You're misapplying Ohm's law here. The wattage of the bulb remains the same, it's the current draw that changes. So a 100 watt bulb draws 0.83 Amps at 120 volts, half of that at 240 volts. Nevertheless we are not exceeding 80% of the wire's voltage rating, shouldn't be a problem. The bulb needs to be changed out to one rated to handle 240 volts, a filament rated for 120 volts will indeed blow with 240 volts across it.

US bulbs use a 1 inch base. From what I can see, Euro bulbs use a 27mm base which is a little too large.

I agree that rewiring is the best plan -- get a local plug, wire, and socket.

When I moved to Dubai, I rewired my lamps. I wasn't sure about the wire and just rewired it while I was at it. Once you are doing the other, the rewiring is easy. By a roll of lamp wire at the appropriate hardware store. Unhook the socket, tape new wire to the old wire and just pull it through.

That's what I would expect to happen.

Great tip - thanks!

I assume you're talking about a lamp, as in table lamp, as opposed to the actual bulb. The voltage difference doesn't matter. However, the socket size for the bulb is different in Europe. We've bought lamps in Europe before, and I simply replace the bulb sockets with U.S. standard ones and, of course, change the plug as well. Works fine.

The North American standard (E26) is actually 26mm (~1.0236 in), so there is a difference of 1 mm in the base diameter of the screw base of the lamp (E26 Vs. E27): http://en.Wikipedia.org/wiki/Incande...ndard_fittings

Also, UK uses a different type of socket altogether.

I stand corrected on the wattage. I guess it's been too many years since Mr. Ryan taught me Ohm's law in junior high.

In any event, I'd rewire the lamp. It would make a nice little project.

I'm not sure. The advertised 240v is RMS (root-mean-square, kind of an average) voltage. Instantaneous voltage at the peak of the sine wave is about 1.4 (square root of 2) times that, or about 340v. While ratings include a safety factor, I wouldn't. Potential downside (short circuit, worse if circuit breaker doesn't kick in) is too big. Rewire. Not hard to do it yourself, not expensive to have someone else do it.

It will draw more current and hence more power, leading to overheating. The wires will get hot. This can cause a fire, trip a circuit breaker and/or burn the filament, if it's an incandescent bulb.

The resistance of 110 V bulb is about a quarter of the resistance of a 220 V bulb for the same wattage. If you power a 110V bulb with a 220V source, it will draw draw four times as much power and twice as much current. Changing the bulb holder, the bulb and the plug that goes into the outlet, or an adapter should suffice. In some countries bulbs are screw mount while in others, they are bayonet mount. The base is different two in width and in the number of electrodes at the bottom.

Got to thinking about Ohms Law again. I'm trying to figure out if I'm missing something here.

The light bulb is rated in watts at a certain voltage, isn't it? The resistance of the bulb (as measured by an ohm meter for example) is a constant.

See http://www.ac.wwu.edu/~vawter/Physic...esistOhms.html


So if P = I E, and P=100w, E = 120v, then I = .83A

E = I R, and R is constant (139.5). so double the voltage, same load, you double the current. At 240v, same R, I = 1.66A

So P = 240v x 1.66A = almost 400w.