Cheap Chinese LED's safe?

[Y33]

I've been browsing for some simple case lighting and came across a cheap, simple led strip attached to a MOLEX connector on a Chinese website (AliExpress).

They're 12 Volt, single colour LED strips. Nothing fancy.

Now, I was wondering whether or not using something like this is safe. Can they short out? Cause fire (seems unlikely for LED strips but still...).

 

Or, long question short, can something like this harm my power supply or system? And are there advantages to buying one from a local hardware store instead?

[dany_boy]

I've never had any problems with Chinese stuff burning or causing damage. After a while the silicone will turn stiff and yellow, and the LED's will begin to die but that's about it.

[TechSquidTV]

They won't be dangerous. The LED won't draw more power at some point causing a sort or something. They would only ever really burn out, and you just replace it.

[Guest]

16 minutes ago, ylst said:

I've been browsing for some simple case lighting and came across a cheap, simple led strip attached to a MOLEX connector on a Chinese website (AliExpress).

They're 12 Volt, single colour LED strips. Nothing fancy.

Now, I was wondering whether or not using something like this is safe. Can they short out? Cause fire (seems unlikely for LED strips but still...).

 

Or, long question short, can something like this harm my power supply or system? And are there advantages to buying one from a local hardware store instead?

Nah your fine. Also, it's made for a PC. It saves doing the work of adding a molex connector.

[Y33]

6 minutes ago, Ampix0 said:

They won't be dangerous. The LED won't draw more power at some point causing a sort or something. They would only ever really burn out, and you just replace it.

And them burning out won't be able to cause any harm either?

 

2 minutes ago, Factory OC said:

Nah your fine. Also, it's make for a PC. It saves doing the work of adding a molex connector.

Yeah that's the only reason I'm even looking into them. Strips are easy to find here but I can't seem to find a MOLEX connector anywhere (I'd have to salvage one).

[Guest]

1 minute ago, ylst said:

And them burning out won't be able to cause any harm either?

Nope, that single LED will just not work anymore.

[mariushm]

Most LED failures are bond wires burning up or disconnecting (the tiny gold wires that connect the diodes to the packaging material (the led case, the metal contacts that get soldered to pcb)

If a diode inside the led package dies in some way that it stays shorted and not open (as if the diode isn't there), the bonding wires are so thin that they act like fuses and burn up or desolder themselves (rarely, as most often the bonding wires are ultrasonically welded to the package, not soldered with regular solder that would melt at 180-220 degrees Celsius) so again, the diode would be disconnected from the power supply.

 

If by some critical scenario in extreme circumstances those bonding wires don't break and the led becomes like a short circuit, the current going through the led would still be limited by the current limiting resistors on the strip, those black rectangles with 331 written on them in the pictures (in the link above). 331 means 330 x 10¹ or 330 ohm, which means that the current through each led is limited to  [ 12v - (3 x ~3.2v) ] / 330 = about 0.01A or 10 mA of current through each led.

 

In extreme failures the led packaging could overheat and smoke and the white plastic would brown up, but it's unlikely to ignite with flames as the resistor would limit the current going through the led. If somehow if you're extremely unlucky a resistor would also short out and let a lot of current go through, then the led packaging could eventually go in flames but by that time the shorted resistor would make smoke and you'd see it failed and the plastic case of the led would also make a lot of smoke and stink so you'd know something seriously wrong is going on with the strip of leds.

 

The strip itself is unlikely to burn , because it's just fiber glass glued to a thin sheet of aluminum (to dissipate heat better) ... it's nothing that can naturally burn.

 

[Y33]

1 minute ago, mariushm said:

Most LED failures are bond wires burning up or disconnecting (the tiny gold wires that connect the diodes to the packaging material (the case, the metal contacts that get soldered to pcb)

If a diode inside the led package dies in some way that it stays shorted and not open (as if the diode isn't there), the bonding wires are so thin that they act like fuses and burn up or desolder themselves (rarely, as most often the bonding wires are ultrasonically welded to the package, not soldered with regular solder that would melt at 180-220 degrees Celsius) so again, the diode would be disconnected from the power supply.

 

If by some critical scenario in extreme circumstances those bonding wires don't break and the led becomes like a short circuit, the current going through the led would still be limited by the current limiting resistors on the strip, those black rectangles with 331 written on them in the pictures (in the link above). 331 means 330 x 10¹ or 330 ohm, which means that the current through each led is limited to  [ 12v - (3 x ~3.2v) ] / 330 = about 0.01A or 10 mA of current through each led.

 

In extreme failures the led packaging could overheat and smoke and the white plastic would brown up, but it's unlikely to ignite with flames as the resistor would limit the current going through the led. If somehow if you're extremely unlucky a resistor would also short out and let a lot of current go through, then the led packaging could eventually go in flames but by that time the shorted resistor would make smoke and you'd see it failed and the plastic case of the led would also make a lot of smoke and stink so you'd know something seriously wrong is going on with the strip of leds.

 

The strip itself is unlikely to burn , because it's just fiber glass glued to a thin sheet of aluminum (to dissipate heat better) ... it's nothing that can naturally burn.

 

Ok, so them burning is very unlikely. But could they harm my power supply in any way if the strip would become a short circuit?

And is there a safety advantage to buying more expensive LED strips locally? Are they better protected against shorting out than a simple strip like this?

[mariushm]

No, power supplies these days are single rail or multi rail but with stupid high current capabilities, like 20-30 A per rail

 

If by some miracle the strip would fail so catastrophically that it's a short which won't break by itself, you still have the thin wires between the connector strip and the molex connector which can probably only handle about 2A continuously.. if there's a short, they'd act like a fuse and at maybe 8-10A the insulation on them would melt (again making a bit of smoke and smell) and then the copper wires would glow white and eventually break.

 

If somehow the thin wire doesn't break , the molex connector itself is rated for 5A per contact, so at around 10-15A the contacts would be so hot that the plastic of the connector would start to brown out and make smoke and the contact could expand enough to break the connection.

 

If the connection isn't broken... the power supply won't care, technically the AWG18 wire between the molex connector and the power supply can carry about 8-12A so around 120-150 watts so any decent 500w or higher power supply can give that much power for ever... the power supply wouldn't be able to make the distinction between a shorted led strip and let's say a video card's pci-e 6 pin connector, it will keep pumping 100 watts or more into that short circuit until something eventually breaks (resistors get carbonized, copper eventually breaks down etc)

.

 

[Y33]

2 minutes ago, mariushm said:

No, power supplies these days are single rail or multi rail but with stupid high current capabilities, like 20-30 A per rail

 

If by some miracle the strip would fail so catastrophically that it's a short which won't break by itself, you still have the thin wires between the connector strip and the molex connector which can probably only handle about 2A continuously.. if there's a short, they'd act like a fuse and at maybe 8-10A the insulation on them would melt (again making a bit of smoke and smell) and then the copper wires would glow white and eventually break.

 

If somehow the thin wire doesn't break , the molex connector itself is rated for 5A per contact, so at around 10-15A the contacts would be so hot that the plastic of the connector would start to brown out and make smoke and the contact could expand enough to break the connection.

 

If the connection isn't broken... the power supply won't care, technically the AWG18 wire between the molex connector and the power supply can carry about 8-12A so around 120-150 watts so any decent 500w or higher power supply can give that much power for ever... the power supply wouldn't be able to make the distinction between a shorted led strip and let's say a video card's pci-e 6 pin connector, it will keep pumping 100 watts or more into that short circuit until something eventually breaks (resistors get carbonized, copper eventually breaks down etc)

.

 

Great! Thanks for the very informative answers! Precisely what I needed to know.