brian.w

I have purchased a wall lamp i could not get or buy in the uk,so got one from usa,i can use a step down transformer to work it in the uk,but i posted on here some while back about lamps from the usa and was told,depending on its specs i can change the plug etc.
Is this right can i cut the plug off and say maybe change the bulb or will the bulb be ok to use,so would i just need to fit a uk plug.
I need to be sure that once the plug has been cut off that i am able to use it as i would just work it with a transformer.
It says on the back of lamp:
120v 60hz 15w max 2 amps.

Anyone able to give me info if i am able to change to uk specs or best leave as is,the lamp is brand new and i dont want to spoil it if i find i cant change it,would it just be the plug that needs replaced or would it be also the bulb and also the cable or would the cable be ok.

tonrob

In theory changing the plug and the bulb should be okay - assuming the type of bulb fitting is also used in the UK. The only other potential hurdle - and I don't know the answer to this - is that does a higher voltage bulb generate more heat? Just assuming that any casing around the lamp would have been designed with a specific heat tolerance in mind.

No point buggering about with transformers, especially as you'd probably be stuck for a replacement bulb (of US type) in the UK when the current one decides to give up.

paddingtongreen

Need more info.

At 15W, that sounds like a full spectrum lamp. Is it?
How is your transformer wired? it probably has a lead with a British plug, but is the secondary (the 120V) a socket or do you have to hardwire to it? If it's a socket, what type?

If you can get the equivalent bulb at 240V, it might have been better and safer to have the lamp rewired for that bulb with a British plug.

brian.w

spectrum lamp. Is it? what is a spectrum lamp,its just a red bull can shaped lamp that hangs on the way that you might find in a bar,pub etc.
As for the stepdown transformer this was used when i had a usa dvd player back in the days when dvd was not in the uk,so i could use that to power it.

But i thought i was able to cut the plug off use a uk one and change bulb,now i am getting different info now,maybe i am best leaving it as is,anyone got more info.

Ray

Thats a must ....

paddingtongreen

No problem if you can get a 240V, 15W bulb with the same fitting, then you can just change the plug. If not, you could have both the plug and the bulb socket changed to take a UK bulb. Just stick to the 15W limit, anything larger might produce too much heat.

fatbrit

FYI -- heating effect is proportional to I^2R. Hence a higher voltage generates less heat for the same power.

penguinsix

There is a rather large posting on the differences between US and UK electrics on the US expats in the UK site that might be helpful

http://talk.uk-yankee.com/index.php?topic=12567.0

md95065

That doesn't make sense.

Heat dissipation is proportional to the power (which is what I^2R gives you) so it doesn't make sense to say that "a higher voltage generates less heat for the same power" - same power is same power is same power which amounts to same heat dissipation.

Of more concern is the fact that unless you completely rewire the lamp it probably has a crappy little switch in it somewhere that I wouldn't trust with 12 volts let alone 240 ...

fatbrit

Well I already assumed you knew W=VI so I didn't bother with that one. You either understand basic physics or you don't, I'm afraid! Have you ever considered why they transmit electricity at extremely high voltages? Or why the lead to your electric kettle or iron in the US is rather thick compared with a UK one? The answers are in them there equations.

tonrob

Bloody hell this thread is getting interesting. More! More!!

md95065

Absolutely, but as you obviously understand, 15 watts of power is still 15 watts regardless of whether it comes from a 120V lamp or a 240V lamp (the latter having 4 times the resistance and, at twice the voltage, consuming half the current of the former, and thus dissipating exactly the same power).

Now, if you had said that higher voltage requires less current to generate the same power, and that means you can either use a thinner cable to feed the lamp or use the same size cable had have a lower voltage drop along it that would have made some sense ...

Tarkak9

just hang around for the "push n' twist vs screw-in bulb... which one to use?" thread.


How many expats does it take to......

paddingtongreen

You got it, cross purposes, FB was talking about the delivery cable, and you, the bulb.

The interesting thing with raising the voltage for transmission is the increase in insulation thickness that is required. For part of my working life, I designed High Voltage transmission lines. A black art, I hated it.

paddingtongreen

It's not "push and twist", it's "bayonet", the bulb goes into a "bayonet fitting".