rewiring a foreign plug

[maisiemouse]

Hi, could someone help me, I recently bought a set of fairy lights from Thailand which had a funny two pin plug so i decided to cut it off and rewire it to a normal three pin but when i cut it there was no colours to tell me which was the live and neutral wires. Is there any way of finding out which is which? If i did wire it the wrong way what would be the result? Please could somebody help. thanks

[ban-all-sheds]

Not wishing to induge in any incompetent-johnny-foreigner stuff, but are you sure that these lights are safe?

Are they CE marked?

Are they marked as conforming to any quality/safety standard whatsoever?

Are they suitable for a 230V supply?

[slippyr4]

Thailand is 220V/50Hz. So, they'd probably technically work here, although might not be safe.

If they're incandescent lights, (not LED's), then it doesn't matter which you put in live, and which in neutral).

However, given that you can get 100 twinkly lights from woolies for less than a fiver, it seems a bit silly to take risks with unknown quality johnny-foreigner stuff.

[ban-all-sheds]

slippyr4 wrote:

Thailand is 220V/50Hz. So, they'd probably technically work here, although might not be safe.

Unless made there for the Japanese or US market...

Quote:

However, given that you can get 100 twinkly lights from woolies for less than a fiver, it seems a bit silly to take risks with unknown quality johnny-foreigner stuff.

Dodgy 230V lights wrapped around a tinder-dry resin-filled pine tree? What could go wrong?

OTOH - these could be the same lights that you buy in woolies...

[Adam_151]

slippyr4 wrote:

If they're incandescent lights, (not LED's), then it doesn't matter which you put in live, and which in neutral).

It wouldn't matter anyway, ... its AC, the worst that could happen is if its a really crap set that dosen't rectify to DC, they you'll end up changing which half cycle they light on

[slippyr4]

Adam_151 wrote:

slippyr4 wrote: If they're incandescent lights, (not LED's), then it doesn't matter which you put in live, and which in neutral). It wouldn't matter anyway, ... its AC, the worst that could happen is if its a really rubbish set that dosen't rectify to DC, they you'll end up changing which half cycle they light on

I was thinking that LED lights would probably have some kind of a controller, which might care.

[Adam_151]

slippyr4 wrote:

I was thinking that LED lights would probably have some kind of a controller, which might care.

It couldn't possibly 'know' without an earth...

[Steve]

oooh now then . . . when i go to the shops and look at those white LED chains of xmas lights, they look like they are flickering very fast, is this because of the lack of a rectifier, and they are only lighting on half of the cycle?

[slippyr4]

crafty1289 wrote:

oooh now then . . . when i go to the shops and look at those white LED chains of xmas lights, they look like they are flickering very fast, is this because of the lack of a rectifier, and they are only lighting on half of the cycle?

the led lights flicker no more than a fluorescent tube. they've probably got an electronic controller for tacky effects.

[plugwash]

slippyr4 wrote:

If they're incandescent lights, (not LED's), then it doesn't matter which you put in live, and which in neutral).

the only reason you should ever need to care about live/neutral reversal with remotely modern equipment is correct operation of single pole isolation and protective devices. since theese lights presumablly have neither inside them it really shouldn't matter which way round you connect them.

the type of lamp is of absoloutely no significance whatsoever (it would be in a DC system but mains is AC).

[Spark123]

In 240v series type string where both the wires run together I like to wire L to the nearest lamp to the plug as this allows the use of an MK powertracer (or similar) to find the dud lamp.

[ban-all-sheds]

Don't most lamps these days have internal links that close the circuit when they fail, so that the string doesn't go out?

Easy enough to spot the dud when they are off the tree - and when they are on there you don't know that one has gone, unless it's a really obvious one.

[Steve]

ban-all-sheds wrote:

Don't most lamps these days have internal links that close the circuit when they fail, so that the string doesn't go out?

yes they do, the only exception is the fuse bulb if the set has one.

incidentally, a few years ago, we bought a "pre-decorated" tree from b&q complete with a chain of 50 lights. After a few days of having it up, i noticed a few lights had gone out. odd, i thought, but left them be for a bit. Another few days passed, an i noticed the bulbs were very bright. i took them off the tree and more than half the bulbs had blown. I was quite shocked by this, since the bulbs that were burning, were taking twice their rated voltage, and producing more heat than they should, it could have easily caught fire on the tree. I was also worried about why the fuse bulb didn't blow . . . that's its job, isnt it, protecting against situations like this?

We took them back to b&q anyway, and they told us to pick another set of equivalent price. problem was, they dont sell this set of lights on their own, so how were we to know the set of 100 we picked was more expensive . . .

[plugwash]

ban-all-sheds wrote:

Don't most lamps these days have internal links that close the circuit when they fail, so that the string doesn't go out?

they do however such links are NOT 100% reliable!