American Power Strips and Monitor, and British Electricity

After living in the United States for over 20 years, I am about to move back to my native Britain. With me are going my laptop computer and various other bits of American bought electronic equipment, most of which are powered off the proverbial “wall wart”. Although American electricity is 120V at 60Hz and British is 230V at 50 Hz, the wall warts and laptop power supply all seem to be rated as capable of dealing with both types of current (and points between). So far, so good.

But, two issues:

  1. British plugs and American plugs are radically different, and in most cases (not the laptop power supply itself, but most of the other peripheral thingies I have) the prongs of the American style plug protrude directly from the “wall wart” power supply, so you can’t just fit a new plug to the end of the wire. In preparation, I have already bought a couple of adapters that will take an American style plug and then plug into a British socket, but I have whole bunch of these electronic thingies and I do not want to have to buy separate adapters for every one of them, if I can avoid it. It has occurred to me that if I take an American style power strip (of which I have several) back to Britain with me, I can use a single adapter to plug the power strip into a British socket, and then plug to American “wall warts,” with their American prongs, into the power strip. I am concerned, however, that this might not be safe. To the best of my knowledge, power strips made for the U.S. market are not made with international electrical , and, particularly British voltage, in mind (unlike the power supplies for American electronic thingies). On the other hand, none of these things is going to draw very much power (well, there is a printer - maybe that ought to have its own adapter - but all the other thingies are very low power). The wattage (and ampage) going through the power strip is (I am fairly sure) going to be pretty low. What I do not know is whether subjecting an American made power strip to the high voltage of British current is potentially dangerous, even at low wattage. I am hoping that someone who understand electrical stuff better than I do can tell me.

  2. As well as all the little thingies with their wall warts, I also have a full size flat-screen monitor that I would also like to be able to use with the laptop. It is a generic Dell monitor that came with my old desktop computer, which I am now abandoning. This, however, has no separate power supply: it just plugs straight into the (American) wall socket (or power strip), and I cannot find anything on it to tell me what current levels it is rated for. Are flat screen monitors normally made, like laptops and other little electronic things, so that they will run on different voltages in different countries, or does everyone assume that they are too awkward to transport, and just make them to run on the electricity of the country where they are sold? Even if the latter is the case, I might be OK, because I actually do possess a transformer that steps between British and American voltages (for relatively low power levels), but it occurs to me that, for monitors, the frequency of the mains current supply might be an issue even apart from the voltage. Is that the case?

Any electrical engineers who can enlighten me (and stop me setting fire to myself)?

  1. Using a single adapter isn’t a good idea. As you’ve noted, it isn’t the wattage that’s the problem, it’s the voltage. The insulation in the wires and the spacing between internal conductors in the power strip are all designed for 120 volts.

  2. I wouldn’t assume anything. Most devices made to handle wider voltage ranges will say something like input 120-240 volts or something like that. If it doesn’t say anything on the monitor itself, you can maybe look up the specs at the manufacturer’s web site or shoot them an e-mail if they don’t list it there either. If all else fails and you can’t get an answer, don’t try it.

How many adaptors are we talking about here? It might be less painful in the long run just to buy replacements with native UK pins - you can often find these fairly cheap on eBay.

I have in my hand a US multi-outlet power strip that is rated to 240v (I can’t say how common this is). I have used it as you propose on various trips to countries with 220-240v mains power, so far always with good results. Note that when operating at the higher voltage it will usually be the case that current is less.

As for the monitor, it looks as if you have two choices: Obtain the specs, or plug it in and see what happens.

In my experience they aren’t very common. I poked around on the net and couldn’t find any rated for 240 in the first 20 or so that I looked at. You might find one in Britain though, especially in the hardware stores in and around the tourist areas.

They also make universal power strips though. Here’s one example:

Again, these aren’t commonly found in stores in the U.S. but can often be found in tourist areas all around the globe.

(Note - I’ve never used the above product and don’t know how good or bad it may be in terms of quality)

IANAE, but… I did stay at a Holiday Inn Express and blow up the wife’s hair dryer. (Actually, I rotated the little switch from 120 to 240, but it didn’t click all the way into position - hence the burning smell and subsequent lack of heat or fan. And it wasn’t HI-Ex…)

The problem with a power bar may be that they are too smart. The fancy onces are not just an extension strip, they also have surge suppression, a mechanism to bypass excessive voltage surges. This may be as simple as a neon bulb, or some fancy electronics (thyristor?). Regardless, I suspect they were not designed with tolerance to much higher voltage in mind - just the opposite. If you can find a simple power strip, no fancy crap, then basically it’s an bigger version of the plug adaptors. OTOH, even the master power switch may not be designed for 240V use. Maybe one of those extension cords with 3 outlets on the end would be more appropos.

As for the monitor - well, find the specs or take a chance. I did also blow up a battery charger once, by not reading the fine print. (Necessitating buying a new AA charger in the Sydney airport). So there are some devices out there that truly cannot support 240V. Since most such devices immediately convert AC to DC (and step down) I doubt the frequency will be an issue. Also, you might be able to find in some hardware or junk shop those power cords with the standard computer plug on one end and the local plug on the other, allowing you to bypass the adapter. Not sure whether most travel power converters are designed to operate for the duration and lifetime that you may expect to get from a monitor… by the time you buy a good one, you may as well just buy a new monitor?

They are usually metal oxide varistors (MOVs) and they are typically designed to clamp the voltage at somewhere around 300 to 400 volts. For surge suppression, the lower the number, the better. It should be listed as “clamping voltage” or something similar in the specs for the power strip. Poking around on the net I did find one with a clamping voltage of 200 volts, so this would be an issue if you tried to run it at 240. Most were above 300 though.

The two wire plugs on the warts may work with the power strip and a conversion plug. Most (heh-heh) did fine. I’ve been over and back to Europe, Asia, and the Middle East several times and had the same problems.

Three wire plugs may induce flames, may work, may not work. In the US at 120V, you have a hot, ground, and neutral. The three wires in Europe 220/240V have two hot legs and a neutral (mostly - and now more standardized). So you can see the potential problem.

Some things like the computer (power supply) you can just buy a new power cord from the brick to the wall and things will be fine (100V~240V). Note that some desktop power supplies have to be manually switched from 120V to 220V.

That’s not true of the UK - we have Live, Earth and Neutral here.

you’re half right; what you say about 220/240V is correct for US Residential single-phase power. It’s not true for ROW 230 VAC; theirs is one hot, one neutral.

I suspect that a monitor might be dependent on not only the voltage, but also the frequency, and likely uses the line frequency to set the refresh rate. If so, it’d almost certainly cause problems when plugged into British power, even if you had a transformer to correct the voltage.

old CRT TVs, maybe, but anything modern is highly unlikely. The mains frequency won’t make it past the switch-mode power supply.

This seems solid advice.

Get rid of any appliances that can’t handle 230v (eBay/craigslist whatever) and get new ones (or get secondhand ones).

Especially something so mundane as an LCD monitor isn’t worth the hassle.

(Older) Television might have used 60Hz to set the vertical sweep, but most computer video cards have had configurable vertical sweep from 50 to 80Hz or more for about 2 decades.

Plus, if it’s LCD then the vertical sweep issue is irrelevant. I’ve had LCD monitors that (like a laptop) use an external brick to produce 12VDC.

IAMNAE. Your description is a bit unclear to me (maybe because I don’t have enough experience with flat-screens yet), but can you connect the monitor to your laptop/ PC to route it through there instead of connecting the monitor directly to the wall? Because in older PCs this was common often: two plugs on the PC, one to connect the PC to the wall socekt, the second one to connect the monitor to the PC. Not all new PCs have this, however.

Because if your PC gets “normal”, that is, stepped-down power, through the adapter in the brick, then maybe the monitor can get low-power (120V) from the PC instead of high 230 V from the wall. Depends on how things on the monitor and the PC/laptop are set up.

It has been a while, but I think that when I worked in the wire and cable industry, the lowest UL rating was 300 volts. So the wire should be good for 300 volts.

Freakin’ Druids. :smiley: :smiley:

I’d urge you to dig around for proper interconnects per product. Some float very happily from 120 to 240 ( nominals ). Some may fry- or shock you. What do the manufacturers recommend? Very few intent products to be used only in the USA.

Here’s how to wire a plug. Make the Earth lead a little longer than in the photo in the link, it should be the last wire to become detached from its terminal should the cord grip fail and the flex be tugged hard. UK mains plugs are cheap and reliable, unlike intercontinental mains adaptors, which often don’t provide very good grip for the plug, and can be particularly troublesome with heavy wall warts. I’d just chop off the US plugs and fit UK ones, it’s the safest and most reliable solution if it’s done properly.
Check the fuse rating also. You’ll mostly need 3 A fuses, the highest rated 13 A being reserved for high power items like washing machines and kettles.

Up until relatively recently, electrical equipment supplied in the UK came without a plug attached, just a prepared cable with bare wire ends, and the consumer had to wire on their own. There was a handy sticker telling you how to do this. Eventually the law was changed to force manufacturers to supply appliances with plug already fitted, as often people would get it horribly wrong.

Most modern electrical equipment is designed for a global market, accepting about 90 V to 260 V AC, but always check; it will be specified on a label on the item somewhere. Hi-fi equipment might be a problem, as these tend to use mains transformers designed for a particular voltage and frequency. Sometimes there’s a voltage selector switch that can be changed, but check the operating frequency.
Leave your surge-protection extension leads in the US though, they’re unlikely to be rated for 230 V, for the reasons others have given.

Peak or RMS?

Thanks to all for the good, if disappointing, advice.

That’s what I was afraid of. Thanks.

I need to have another good look at the monitor, but, so far, not only can I not find a voltage rating, but I cannot find any particular model name, just a generic serial number. I do not really know what model it is, apart from being a generic Dell. I guess, under the circumstances, it is probably not worth transporting it halfway around the globe (although, given the weird economics of international shipping, it probably would not cost me anything to add one more box to my already considerable load.)

That sounds like what I need. I wish I had realized earlier. There is a pretty good electrical supplies store fairly near me, so if I have time before flying I will try there. If not, I will have to look for something suitable once I am England.