Rewiring an English Lamp for American Use

[Amethyst]

When we returned from England, we brought along a pair of bedside reading lamps that I just fell in love with. They are solid brass and pretty. They also gave a great light for reading.

A few years ago, I took them into a local lamp store (since gone out of business) to get them rewired. They wouldn't do the job. It was never clear to me why not.

So I have looked on Youtube, and it seems like replacing lamp guts is not a big deal - but then why wouldn't the lamp store at least work with me? Am I missing something hard about yanking out (No Pun Intended) UK lamp guts? I realize that English lamp bulbs burn far brighter b/c of the 240 volt power supply, yet I'd think today's LED bulbs would make up for that.

Attached are some photos: the lamp, the wiring, the bulb aperture. The base is covered with felt, which I can remove. Can anyone see anything that would make the switchover difficult? Happy to provide more photos, if it will help.

Thanks,

Amethyst

[jazz4cash]

I don't think this should be a problem, esp if you're going to 120V LED bulbs. Does the bulb receptacle fit the threads on standard US bulb base?

[pb4uski]

I like to DIY, so I would disassemble it and replace the lamp base, wiring and plug with new.

Have you tried any other lamp shops?

OTOH, if a US light bulb plugs into the base you might just change the plug to a US style plug... I can't see that running 110v through a wire sized for 220v would be a problem.

[braumeister]

I'm sure you realize that just as English cars drive on the opposite side of the road, English electricity flows through the wires in the opposite direction.

So you will have to reverse everything (negative becomes positive, AC becomes DC, current becomes impedance, voltage becomes resistance, etc.)

I'm not surprised your local shop didn't want to touch it -- this is a very tricky proposition and one mistake could turn the technician into a puff of smoke.

Of course, I may not be entirely correct about all that.

[Walt34]

Quote:

Originally Posted by pb4uski OTOH, if a US light bulb plugs into the base you might just change the plug to a US style plug... I can't see that running 110v through a wire sized for 220v would be a problem.

What he said.

I don't see any reason why a lamp shop would refuse to do it, other than perhaps liability. Any reasonably bright Middle School kid could do it.

Even if the socket thread is different, finding a standard Edison light bulb socket isn't that hard. Any hardware store worthy of the label will have several different kinds.

Here's a selection from Amazon: https://www.amazon.com/edison-bulb-s...0bulb%20socket

[pb4uski]

Actually... funny story... DSister went to london with BIL and she used he blow dryer with an adapter (not a transformer) and she was initially amazed at how well the dryer was drying her hair.... until it burnt out.

[samclem]

>Technically<, if the UK bulb is 220V and 100W, and the US bulb is 120V and 100W (so both bulbs have about the same brightness), then the US bulb would be using almost twice the amperage of the UK bulb. Wire sizes are determined by amperage, not wattage or voltage, so it is >technically< possible that a wire/cord that is sufficient for the UK bulb would be insufficient for the US bulb.

Now, if you are going to use an LED bulb, it would probably be drawing far lower amperage than the UK 220V incandescent bulb, so you'd be fine--as long as nobody ever screwed an incandescent bulb into that lamp. And there's no way to guarantee that.

You could check the wire size and the ratings of the switch to know if it would work for a US bulb. My >guess< is that you'll find the wiring and switch to be of sufficient capacity for what you want to do, but that's not a substitute for actually checking.

[ERD50]

From wiki:

https://en.wikipedia.org/wiki/Edison_screw

Quote:

There are four commonly used thread size groups for mains supply lamps: Candelabra: E12 North America, E11 in Europe Intermediate: E17 North America, E14 (Small ES, SES) in Europe Medium or standard: E26 (MES) in North America, E27 (ES) in Europe Mogul: E39 North America, E40 (Goliath ES) in Europe. The E26 and E27 are usually interchangeable, as are the E39 and E40, because there is only a 1 mm difference in thread outside diameter.

The picture looks like a standard US plug - can you take a picture of one next to it for reference?

Quote:

I realize that English lamp bulbs burn far brighter b/c of the 240 volt power supply, yet I'd think today's LED bulbs would make up for that.

I guess all those English people wear sunglasses in their homes, huh?

Seriously, their bulbs aren't brighter, they are designed to give the desired brightness at that higher voltage. So a '60 watt' bulb has about the same brightness there as here, you just need the right voltage bulb for the voltage supplied.

Trivia - our NA filament bulbs are slightly more efficient than the Euro-bulbs. Our 110 V system is the 'sweet spot' for filament length and support requirements.

That said, a high voltage bulb takes less current, so the wires could be thinner. But I'd bet the wires are plenty thick for any sized bulb you plan to use, usually they are thick to stand up mechanically, and are over designed electrically. So that should not be an issue unless the cord seems to be very thin wire.

-ERD50

[bingybear]

It looks like someone has already tried modifying this. That is likely why then did not mess with it. The plug does not look like the standard UK plug - 3 prong.

The easiest way with a true UK device unmodified would be to get an adapter plug with built in transformer the could supply the UK voltage and current that the light needed. Also it should be designed with appropriate grounding and fuses. Here I am thinking a type G connector. This is what I had in my house in the UK in the late 90's.

This would not require any mods to the light at all.

Assuming the bulbs (120 VAC and 240 VAC) are the same power, the 240 VAC wiring would be designed for about half the current of the 120 VAC bulb. Usually this is designed with enough margin... or I would expect so.

I can't tell looking at the light socket if that would fit a US bulb and I don't recall the UK bulbs.

If I were a shop that was asked to modify something like this, I think I would want to do a complete US conversion as I'd expect that the store would be taking some liability for the operation over time.

The real question is does a US shop have parts that would fit the lamp but meet the US requirements. I'm guessing not if they were not willing to do the work. But I don't know.

I would expect the work would be pretty easy with the right parts.

[OldShooter]

Jeez. The thread reminds me of those engineering meetings where we evaluated three alternatives and boiled them down to seven.

It looks like it already has a USA flat-pin plug and a socket that would take a standard Edison base bulb. I'd look it over very carefully for frayed wires or other bad things, then put a bulb in it and plug it in. If the light comes on and the switch works (most probable) you are done. If something starts to smoke (unlikely), unplug the light without touching the metal parts. If something really exciting happens, your panel breaker will pop and unhook the light for you. An ounce of data trumps a pound of theory.

Re current yes the English mains 220v results in half the current for a given wattage but 100watts is only an amp at 110v. Any wire larger than angel hair will handle that. In addition, we are in the age of LEDs. Even angel hair will handle the current demands of a 60w or a 100w equivalent LED.

NB, the photo is a little blurry but I think there is just one base contact. If there are two (look at a three-way bulb socket to see how this works) you may eventually want to put a three-way bulb in there.

[Amethyst]

All true, and water runs uphill over there as well. Very exciting when you go to flush the loo. After 3 years we were used to it, though.

Quote:

Originally Posted by braumeister I'm sure you realize that just as English cars drive on the opposite side of the road, English electricity flows through the wires in the opposite direction. So you will have to reverse everything (negative becomes positive, AC becomes DC, current becomes impedance, voltage becomes resistance, etc.) I':

[Amethyst]

Does anyone see a problem with simply yanking out the whole insides- including the bulb aperture - and replacing it with entirely new U.S. parts? BTW, that is a genuine UK plug, with a fuse in it. They aren't all 3-pronged.

[samclem]

Quote:

Originally Posted by Amethyst Does anyone see a problem with simply yanking out the whole insides- including the bulb aperture - and replacing it with entirely new U.S. parts? BTW, that is a genuine UK plug, with a fuse in it. They aren't all 3-pronged.

No, that would be straightforward, and you'd be guaranteed not to have any problems. The only potential "gotcha" would be the the requirement for metric nuts/fasteners IF there's anything on the lamp body with a threaded connection that affixes to the bulb aperture. If it's like US lamps (typically just a sloppy hole in the lamp body with all the threads on the aperture or switch), then it probably won't be a problem.

[OldShooter]

Quote:

Originally Posted by Amethyst .. BTW, that is a genuine UK plug, with a fuse in it. They aren't all 3-pronged.

Then I'd change the plug to US style. A new one is probably a buck or two at Home Depot. Then plug it in and see.

If you're a little more cautious, I'd take the light to HD and ask for an opinion. In my experience, their electrical department guys are fairly knowledgeable. Better than SGOTI.

[6miths]

We brought several lamps back from overseas after our three year sojourn. All were two and three prong (fused) British and European plugs and bulbs for 220v. Cut the plugs off, rewired North American plugs, found a North American bulb that fit the fixture threads et voila let there be light!

13 years later they are all still working fine and no dwellings have burned down.

[CardsFan]

Quote:

Originally Posted by OldShooter Jeez. The thread reminds me of those engineering meetings where we evaluated three alternatives and boiled them down to seven.

I gotta save this one. Priceless!

[Amethyst]

For some reason, the "help" in our HD is terrible. I think they have a hard time keeping employees.

I'll post more photos after I finish tearing apart the lamp. Maybe the EE's on the forum will spot something.

Quote:

Originally Posted by OldShooter Then I'd change the plug to US style. A new one is probably a buck or two at Home Depot. Then plug it in and see. If you're a little more cautious, I'd take the light to HD and ask for an opinion. In my experience, their electrical department guys are fairly knowledgeable. Better than SGOTI.

[bingybear]

Quote:

Originally Posted by OldShooter Jeez. The thread reminds me of those engineering meetings where we evaluated three alternatives and boiled them down to seven.

You worked in a much more efficient place. We would have the engineering meeting and that would spawn a tiger team to figure out the best solution. The ISO guru would hear about the project for which we did not have defined process and start a ISO effort to define the process for this new effort. After killing an acre of trees for the process documentation the quality lead would pick up their coffee cup an see the brown coffee ring and declare that was the brown circle of quality. We would leave and no one remembered about the tiger team or the engineering issue the started the whole effort. Soon someone would come up with an idea that would generate the next tiger team and the death of more acres of trees.

[ERD50]

Quote:

Originally Posted by Amethyst Does anyone see a problem with simply yanking out the whole insides- including the bulb aperture - and replacing it with entirely new U.S. parts? BTW, that is a genuine UK plug, with a fuse in it. They aren't all 3-pronged.

That really is the most straightforward, eliminates these variable we keep throwing out to make it sound complicated! Should be easy.

Quote:

Originally Posted by OldShooter Jeez. The thread reminds me of those engineering meetings where we evaluated three alternatives and boiled them down to seven. ...

Your number's too low!

I wasn't going to mention this, for fear of making it all seem too complex to the OP (it really isn't), but in the name of complete safety and disclosure, I must disagree ...

Quote:

Originally Posted by OldShooter If the light comes on and the switch works (most probable) you are done. If something starts to smoke (unlikely), unplug the light without touching the metal parts. If something really exciting happens, your panel breaker will pop and unhook the light for you. An ounce of data trumps a pound of theory. Re current yes the English mains 220v results in half the current for a given wattage but 100watts is only an amp at 110v. Any wire larger than angel hair will handle that. ...

Yes, the wire will handle the bulb current, but... If you get a short in the lamp ("something really exciting"), and the cord is angel hair wire - you may not pop the breaker, until the cord gets hot and possibly starts a fire.

You'll be plugging that cord into a circuit with a 15 A breaker - the cord has to handle that much current safely until the breaker pops. Look at little devices like an alarm clock. They draw a few milli-amps of current, but the cord that plugs in the wall is still ~ 16 GA, it can handle 10 or so seconds of 15 A until the breaker pops. Angel hair might catch fire by then.

What are the chances? One-in-a-million? OK, but codes like this is why we don't have electrical fires more often, with millions of devices plugged in.

-ERD50

[RobbieB]

If a US bulb will screw into the socket, just put a US plug on the cord. Fini.