led lights

[dreadnought]

morning all, can you tell me if it matters witch way round you wire an led light, i`ve got two wires comming out of my lights and they are both white so can i connect the live to any one and they neg to the remaining one, many thanks,

[manxmike]

Hi Dreadnought, doesn't matter at all - it's DC so it won't affect the lights.

[Graham Davis]

On some it does matter, but if you do connect them up the wrong way it doesn't damage them, they just don't turn on. If that happens just swap the leads around.

[Tony Brooks]

Hi Dreadnought, doesn't matter at all - it's DC so it won't affect the lights.

 

I think that you have AC and DC mixed up.

 

Filament lights do not care which way round you connect them on AC or DC but Dreadnought asked about LEDs that very probably have electronics inside them and electronics are likely to blow if you reverse connect them. However things made for the consumer market may put diodes in the supply in a manner than makes them polarity insensate. The LED lights are probably like this but I would say check with the supplier to be sure.

[WotEver]

Dreadnought asked about LEDs that very probably have electronics inside them and electronics are likely to blow if you reverse connect them. However things made for the consumer market may put diodes in the supply in a manner than makes them polarity insensate. The LED lights are probably like this but I would say check with the supplier to be sure.

^^ this is good advice.

[David Mack]

If the LED is fitted with identical wires with no distinguishing features, that would suggest to me that the polarity does not matter.

 

If you ask the supplier what can he tell you? "Connect the white wire to the positive and the white wire to the negative"?

[Hairy Animal]

A quick check on eBay doesn't show any actual 12V LED (Light Emitting Diode) lamps with wire connections, there may though be some and if that's the case, the polarity certainly wouldn't matter if the wires are the same colour.

 

It sounds more likely though that it's the light fitting which has the two white wires. Three possibilities:

1. it's designed for tungsten bulbs where the polarity is irrelevant;
2. it came fitted with an LED bulb, in which case the polarity probably doesn't matter, but if it doesn't work one way round, try the other, no damage is likely;
3. an LED bulb's been fitted to an older tungsten bulb fitting - some LED bulbs have bridge diode arrangements that will work off AC or either polarity DC, others (cheaper) are polarity sensitive (the diode is a one-way valve electrically) but usually won't be damaged by reverse polarity. Generally, such a bulb has two pins and can be inserted in the socket either way round. If that's the case, just take the bulb out and turn it round, quicker than rewiring the fitting.

Hope that helps?

[MtB]

The cheap ebay LED lamps in my boat are most certainly polarity conscious. I just took one out and reversed it to check. It didn't work.

 

The expensive ones from Bedazzled work either way around though.

[WotEver]

Canbus LEDs for a car are similarly polarity conscious and aren't damaged by reverse connection - they just don't work.

 

Tony

[cuthound]

Many boats will have G4 (capsule) halogen lights, or the "car sidelight" type.

 

I have replaced some G4's and either I was lucky and put them all in the same way around, or they were not polarity conscious. They were sourced from eBay.

[raymondh]

Just fitted 4 of these work either way in the lampholder and are operating at 14.8v at the moment

 

£2.99 for 4 deliverd

 

http://www.ebay.co.uk/itm/381234583050?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

Ray

[DHutch]

If the LED is fitted with identical wires with no distinguishing features, that would suggest to me that the polarity does not matter.

 

Ditto. I would typically therefore be happy just to apply power and see what happens, reversing it if it doesn't work.

 

The only exception might be if it was a raire or particularly expensive unit, with limited change of a replacement.

 

 

As said;

- A native LED and or very simple led cluster with current limiting resistor will only work one way, but will not be damaged if reversed, as the LED is a diode in its self.

- A lot of domestic LED lamps will be arranged with electronics to light either way to make it easier for the end user, in part as as many MR/GU based fittings do not carry a polarity.

- Some circuits used with LED could be damaged by reverse current, however good practice would be for protection against damage if reversed, so the risk of damage should still be small.

 

 

 

Daniel

[ditchcrawler]

The only LEDs that I have had that where polarity conscious where festone type

[nicknorman]

All 12v LED bulbs I've encountered have a bridge rectifier on the input so can be wired either way round. Something like a GU4 / MR11 has 2 identical pins and it would be pretty crap if it were polarity conscious. Plus some domestic supplies for 12v incandescent lights may be AC hence further need for a bridge rectifier. No doubt there are exceptions esp. if you buy at rock bottom prices.

[by'eck]

All 12v LED bulbs I've encountered have a bridge rectifier on the input so can be wired either way round. Something like a GU4 / MR11 has 2 identical pins and it would be pretty crap if it were polarity conscious. Plus some domestic supplies for 12v incandescent lights may be AC hence further need for a bridge rectifier. No doubt there are exceptions esp. if you buy at rock bottom prices.

 

Agreed regarding lighting LED's. Fitted some as direct replacements to low voltage halogen bulbs in my brothers bathroom. The series of spot lights were fed with transformer provided 12 volts AC but worked fine.

 

Have noticed that most tiny indicator LED's are polarity sensitive though, including some where the black wire was the positive feed!

[nicknorman]

Have noticed that most tiny indicator LED's are polarity sensitive though, including some where the black wire was the positive feed!

Certainly individual LEDs are polarity sensitive - they are diodes after all! But once packaged into a bulb designed to be plugged into a domestic incandescent - type fitting I would have thought nearly all had rectifiers.