Whoops. I guess I kinda forgot about that one...
July 2, 2010 9:00 PM   Subscribe

What's the best/cheapest way to adapt a power cord from the UK to an outlet in North America?

So I just bought an alarm clock from the UK, but I completely forgot they use different power outlets. Now I have a really nice and expensive paper holder, but not a very good alarm clock.

This is the end that connects to the clock. and this is the end that connects to the wall.

Other technical specs:
- the wall plug says "13AMP, 250V"
- the clock plug says "2.5A, 250V"


I need to make this work with a standard North American (Canada FTIW) outlet. Can I use any cord that would fit in the clock? (It's just less power right??.....) Should I go out and find an adapter somewhere? (This wouldn't be ideal because of the bulkier plug.) What are my options?

The cheaper the better, but it still needs to be safe and I don't want the chance of causing any damage to my new, expensive clock. ;)
posted by Kippersoft to Home & Garden (20 answers total)
 
I use this American Tourister adaptor plug for my UK appliances and it works fine. Mainly I use it for my laptop's power cord and my hair straightener. It's good because it can do UK --> US, US --> UK, or any other combination from anywhere in the world.

I believe some appliances need a converter as well as an adaptor, but I'm not sure how that works -- everything I've tried with this works fine, though. (The hair straightener has some multi-voltage system for use in various countries without a converter, I believe. I think the computer does this, too.)
posted by Put the kettle on at 9:08 PM on July 2, 2010


Your clock won't work even if you changed the plug because a US or Canadian outlet will only give it half the voltage it is expecting - 120 VAC instead of 250. Most electronics gear now uses switching power supplies that can adapt to the difference, but it sounds like your clock is a simple electric motor type, so that doesn't apply. You might be able to get some kind of step up transformer, though - I don't know how practical that would be though. You might look for a switch like Put the kettle on suggests, though.
posted by rfs at 9:12 PM on July 2, 2010


You want a cord with an C7 plug on one end, and a North American unearthed, unpolarized plug (properly known as NEMA 1...but nobody normal calls it that) on the other. An electronics shop like Radio Shack should have it for a few dollars.

If you or a friend are handy with wire strippers and a screwdriver, you can just chop the UK plug off and replace it yourself with a plug from the hardware store for $0.50.
posted by randomstriker at 9:14 PM on July 2, 2010


Also, if it is an old-style electric motor clock, it will be expecting 50 Hz instead of the US/Canada 60 Hz, and might not keep good time.
posted by rfs at 9:14 PM on July 2, 2010 [1 favorite]


Another reason it won't work is that electric clocks depend on the line frequency to keep time. Your British clock is designed to count 50 power cycles per second. Wall current in North America is 60 Hz, so it'll run 20% fast.
posted by Chocolate Pickle at 9:25 PM on July 2, 2010


if it is an old-style electric motor clock, it will be expecting 50 Hz...
It's a new (2009) digital clock, but the manual says "230Vac 50Hz 70W".

Would there be any harm (ie: permanent damage) in trying randomstriker's suggestion? They also make this clock for North America (it was just cheaper to buy it through the UK), so perhaps it could handle both? (I'll contact the company about it.) And I'm sure I could find an extra cord with the proper end on it laying around.

Otherwise, it's down to the adapter I guess. I just hate the big bulk it has (and a bit more expensive).
posted by Kippersoft at 9:29 PM on July 2, 2010


The "harm" is an electrocution risk. If you wire it wrong, you could die.

Is this really so important? Just buy another one!
posted by Chocolate Pickle at 9:37 PM on July 2, 2010


I would post a barter ad on Craigslist for someone about to move to England and would they like to trade clocks.
posted by rhizome at 9:38 PM on July 2, 2010


I wouldn't rewire the cable, I'd just use an existing one. (I've seen a couple with similar ends to this before.

The clock is a specific one I was looking for and pretty expensive. So replacing it isn't really an option and sending it back is pretty expensive for shipping. ;)
posted by Kippersoft at 9:44 PM on July 2, 2010


Um. I just did almost this exact thing.

I got a voltage transformer like this that both adapts the type of plug and provides the proper voltage for the clock.
posted by Ouisch at 9:51 PM on July 2, 2010


It's a new (2009) digital clock, but the manual says "230Vac 50Hz 70W".

Are you ABSOLUTELY SURE it only takes 240V? Check the back of the clock carefully. I can't remember the last time I saw a modern appliance that couldn't handle both 110V and 220-240V. These days, it's cheaper to manufacture appliances that can take both voltages than to manage separate product lines and disparate inventories.

The fact that the power cord is replaceable implies that it is meant to serve many different markets, and hence both voltages.
posted by randomstriker at 9:58 PM on July 2, 2010


The bottom of the clock shows "230Vac 50Hz 70W(max)". I kind of assumed the same thing though since it is a clock available in many countries (including a American and Canadian dealer) and making a clock able to handle all of them would make sense.
posted by Kippersoft at 10:05 PM on July 2, 2010


If it doesn't say 100-240VAC on the bottom or the manual then it's probably 230VAC only. You'll need a step up/down transformer, like this one, rated for at least 70W. I'm not necessarily recommending that specific item; you might be able to find cheaper or higher quality units.

The other possible issue is the 50Hz. North America uses 60Hz so a clock depending on wall frequency will run fast. But if it's a quartz timer it shouldn't be problem.
posted by 6550 at 10:14 PM on July 2, 2010


The reason it's 240VAC only and not switchable is that there's an incandescent bulb inside, and a 240V light bulb is going to be pretty dim at 120V. The clock electronics presumably have their own power supply inside the case to get whatever low voltage they need.

So one option is to get that step transformer... until that bulb burns out. Then you'll have to source a 240V daylight bulb from somewhere. Shipping light bulbs across the Atlantic might eat up whatever you've saved by buying the UK version, and the bulb won't last that long because of all the dimming.

The other option is to replace the 240V 60W daylight bulb with a 120V 60W daylight bulb and cross your fingers that the power supply inside the case for the electronics can handle 120V.

(Or send it back and get one meant for over here.)
posted by mendel at 10:24 PM on July 2, 2010


Electric clocks don't have quartz timers in them, because counting the wall frequency is more accurate (and cheaper). The power company is very very good about keeping the wall frequency extremely accurate. (I think the spec is +/- zero cycles per month, and I'm not exaggerating.)

So all you need is a multiphase motor and a precise step-down gear set, and your clock will keep time perfectly -- as long as it's designed for the right wall clock frequency. In the case of your clock, it's expecting 50 Hz and that means that it can't be powered using a 2:1 step-up transformer because the power frequency would still be wrong.
posted by Chocolate Pickle at 10:35 PM on July 2, 2010


In other words: You can't get there from here.
posted by Chocolate Pickle at 10:37 PM on July 2, 2010


The fact that the power cord is replaceable implies that it is meant to serve many different markets, and hence both voltages.

Non sequitur: Europe has 240v/50Hz AC across the board, but a wide range of sockets, so interchanging the cord makes sense, but so does making separate 120/230V models. Mains-powered clocks, electric motors and heating/lighting elements really don't do the 240/120V (and 50/60Hz) transition well.

You might think that replacing it is not an option, but how do you feel about having to buy lot of ugly, bulky, expensive and kludgy transformer kit that will have to accompany it around the US?

The cheapest option is to send it back and buy the US version. Whatever that costs you will be less than you spend trying to work around your mistake; comfort yourself with the knowledge that it happens in reverse too.
posted by holgate at 11:05 PM on July 2, 2010


I wouldn't rewire the cable, I'd just use an existing one. (I've seen a couple with similar ends to this before.

There is no risk or danger involved in rewiring the end of a cable, as long as you follow instructions carefully.

That doesn't mean it is going to work.. I think you might be in trouble on that score. The light circuit probably uses a triac dimmer, and the operating voltage will make a critical difference in how that performs. On the other hand, I think it is probably safe to try and find out. The electronics will probably work, but you do run a small but significant risk that the magic smoke will get out. The light bulb won't be nearly bright enough, so it will have to be changed..

In any case, please don't use a step up step down transformer for this job. Since it will be plugged in 24 hours a day, it will waste a tremendous amount of power.



Electric clocks don't have quartz timers in them, because counting the wall frequency is more accurate (and cheaper). The power company is very very good about keeping the wall frequency extremely accurate. (I think the spec is +/- zero cycles per month, and I'm not exaggerating.)

They do keep close to 60Hz, but not that close. The reason it still works well for clocks is that power utilities correct for average frequency over time.
posted by Chuckles at 4:21 PM on July 3, 2010


I think you might be in trouble on that score. The light circuit probably uses a triac dimmer, and the operating voltage will make a critical difference in how that performs.

The operating voltage, AND the AC characteristic. It should be a sign wave input, and absolutely must not be a square wave input or DC, and the frequency might even change performance too..
posted by Chuckles at 4:25 PM on July 3, 2010


Thanks everyone. I had no idea it would be this big of a problem. I've emailed the company to confirm the UK unit is different from the North American unit, but it's looking like I'm out of luck on getting this one to work properly.
posted by Kippersoft at 5:53 PM on July 4, 2010


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