Can I use a 220v device in the UK?
November 16, 2007 11:35 AM   Subscribe

Can I use a lightbox purchased online from the US, which includes an international voltage adaptor for 220v, in the UK? I think the UK mains voltage is 240v and have no idea whether I have to be bang on 240v or if 220v is good enough.

I can save a lot of money by buying it online from the US, so would prefer to do that, but don't want to fry it, myself, or the house. To add to my confusion, there are lots of similar previous questions, but some cite the mains voltage in the UK as 240v, some as 230v, and some as 220v.
posted by penguin pie to Technology (8 answers total)
The 10-20 volt differences between different variations shouldn't matter for a device like a lightbox.
posted by nomisxid at 11:50 AM on November 16, 2007

Short answer: yes. If you're within 10% you should be fine. My light table is a DC device, an external "wall wart" provides 12V to the box, and inside there are electronics to regulate the power.

Another factor is that the frequency is different: US is 60 Hz but the UK is 50 Hz. Shouldn't make a difference for a light table. (It makes a big difference for the older kinds of electric clocks.)
posted by phliar at 11:51 AM on November 16, 2007

The UK mains voltage is 230 V +10% −6%, which means you shouldn't have any problems.
posted by jayden at 12:05 PM on November 16, 2007

I think this is like the difference between calling US mains power "110 volts" versus "120 volts".

One is the voltage at the delivery point into your house wiring, the other is the voltage that appliances are designed to use as a minimum. I.e. the power company delivers 120V to your meter, but your appliances should be able to work at 110VAC, thus allowing you a maximum of 10V drop through your house wiring. (Many modern appliances will say 115V +/- 5 or 10% as a compromise.)

I think 220V is the US 'medium voltage' standard for dryers, because it's what you get if you join both legs of the standard split-phase arrangement. This is used for clothes dryers and stoves.

I'm pretty sure the European standard is 230V, and it might be delivered to the house at 240V to allow for some internal drop (or maybe there's intra-Europe regional variation...maybe one is UK and one is mainland Europe?).
posted by Kadin2048 at 2:32 PM on November 16, 2007

You're fine if your box is incandescent (inc. halogen), fluorescent, or High Intensity Discharge (HID), but if it uses LEDs, please ask the manufacturer directly.

LEDs do not follow ohms law; they can have a large increase in current-- easily enough to burn them out-- from increases in voltage across them of less than 10%.
posted by jamjam at 2:44 PM on November 16, 2007

jamjam: LEDs do not follow ohms law; they can have a large increase in current-- easily enough to burn them out-- from increases in voltage across them of less than 10%.

Even if there were LEDs in the lightbox, LEDs are never driven directly from AC mains. There would be an AC to DC converter in between which is very likely able to handle a range of input voltages and frequencies while producing a constant output voltage. The specifications for the power supply should indicate the tolerance range for inputs.

Even in DC systems, a 10% change in voltage is unlikely to create a problem for LEDs. All LED systems have either current limiting resistors or controlled current sources. They are never connected directly to the DC supply.
posted by JackFlash at 5:48 PM on November 16, 2007

Response by poster: Thanks, everyone. It is an LED box: This is the box in question - a SAD lightbox rather than a graphics one. If you click the features tab it gives you the spec, but I'm a complete electronic idiot so can't make much of the power supply issue. (I'm looking at the box on the left).

I did contact the manufacturers and they just said it was a 220v adaptor (the exact voltage wasn't specified on the website, so they were being helpful up to a point) and advised me to check out the place I'd be using it. I'd already told them I wanted to use it in the UK, so I guess the customer service woman just don't know about the specifics of different countries.

Any further comments on the LED issue more than welcome.
posted by penguin pie at 4:18 AM on November 17, 2007

Response by poster: Did I say "electronic idiot"? perhaps I meant "electronics idiot"
The Electronic Idiot - every home should have one.

posted by penguin pie at 4:21 AM on November 17, 2007

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