DIY COB safety/fire issues

Hey all,

I was wondering if someone could identify and discuss the relative safety/fire hazards of a DIY COB lights?.

I have always assumed that the fire hazard would be less than a HPS or other HID light. Is this correct? What is my biggest danger safety wise building my own light? For example, what happens if a solder fails and the connection with the COB is broken? What if a fan fails(assuming active cooling)? What mitigation/prevention measures can be taken to avoid problems?

Thanks

Billy

Good questions Billy. I have some cheapo drivers that have been running continuously for 3 years and have behaved themselves so far. The only trouble I have had was from poor soldering connections when trying to solder tiny LEDs back in the early days of DIY. Flickery connections are a no-no for constant current LED circuits. I have had strings of LEDs blow out for that reason and I had one driver malfunction and it would blow out anything I attached to it (cost me $125 before I figured it out.) Since moving away from those horribly small LEDs and poor soldering techniques, the only problems I come across are a few dud drivers that put out much less than they claim to and a few de-domed LEDs due to my sanding their stars flat. It may be worth mentioning that the CREE LEDs survived my abuse where others did not.

If the circuit is broken on the DC side the COB will go out but other than that nothing will happen although the driver could be damaged. If the circuit on the DC side is shorted, it may destroy the driver and possibly some/all of the LEDs on that string. It is ideal to have a fast blow fuse on the DC side for this reason and to protect the COB in the case of a river malfunction.

On the AC side. most drivers have fuses. Some drivers also have over temp protection.

If a fan motor burns out, fails to start or a fan power supply fails, the COBs performance could be damaged eventually, but it will not reach temperatures that could start a fire. If a COB somehow falls off the heatsink, it will be destroyed in a short time and the DC circuit may short, possibly destroying the driver or blowing the fuse if you installed one.

SupraSPL said:

Flickery connections are a no-no for constant current LED circuits. I have had strings of LEDs blow out for that reason and I had one driver
malfunction and it would blow out anything I attached to it (cost me $125 before I figured it out.)

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This. Flickery is really not good, especially for switch mode power supplies. Stability in supplies is proportional to load current. Low or 0 load current will lead to an unstable (underdamped) output. This means ringing. Ringing is no good. It could fry everything.

In general, inductors improve stability when current is high. Keep the load current consistent or you may end up with an output signal like this every time it flickers.

So by not addressing the eventuality of a fire directly, does that mean, that the likelihood of that ever happening is ~0 % ? My stuff for my first DIY should be on its way, and this is my only worry. If I fry a COB, so be it, doesnt matter much, but I should hate to worry about a possible fire hazard when away from the room. Im going with ideal holders to avoid a bad soldering job, and ordering renowned meanwell drivers to have my mind at ease, should that be enough?

benbud89 said:

So by not addressing the eventuality of a fire directly, does that mean, that the likelihood of that ever happening is ~0 % ? My stuff for my first DIY should be on its way, and this is my only worry. If I fry a COB, so be it, doesnt matter much, but I should hate to worry about a possible fire hazard when away from the room. Im going with ideal holders to avoid a bad soldering job, and ordering renowned meanwell drivers to have my mind at ease, should that be enough?

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There is always the possibility of a disaster electrical failure condition that could lead to a fire. good components and good craftsmanship minimizes that possibility.

personally I'd think a good soldering job is at least as good as an ideal holder connection if not better as the connection is based on a point to point spring pressure connection.

If you follow simple soldering methods it's pretty hard to mess them up. A 30w iron is hot enough for electronics. Anything higher and you risk burning the copper pads. Antex are a good solid and reasonably priced iron. I went through 4 cheap ones in a year and bought an antex and 5 years later it's still going strong. Plenty of flux as it helps solder stick just remember to clean excess with iso And take your time. And always tin your wire and pad before you try to stick them together. And try and avoid lead solder, it can become brittle. Especially with the amount of heat transfer in these type of connections.

brettsog said:

. And try and avoid lead solder, it can become brittle. .

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I have never heard that one before. I thought the primary reason not to use lead solder was because of environmental concerns. I tried soldering with a non-lead solder and the melting point was way too high for me to manage for my skill level.

funny like the amount of lead in my components is really gonna reduce lead environmental issues.

Lead has a low melting point. I agree it's easier to solder with. U should use a mask. Constant heating and cooling can make the connections brittle and end up with a cold joint. I have always found it to deteriorate over time. I just use lead free, rosin core.

brettsog said:

Lead has a low melting point. I agree it's easier to solder with. U should use a mask. Constant heating and cooling can make the connections brittle and end up with a cold joint. I have always found it to deteriorate over time. I just use lead free, rosin core.

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I tried to search for something about the heating and cooling for leaded solder but all I get is the opposite with lots of hits on reliability issues with lead free solder have any pointers ?

Use a decent soldering iron, keep your tip clean and tinned. I have never got on with gas irons. Soldering is all about accuracy. Practice on something. It's worth finding the sweet spot when it comes to melting point. Some solder has an actual melting point where other types have a range. And always clean up your connections as flux will corrode them quicker than u think. I prefer liquid flux as it comes in like a fibre tip pen applicator. Not the greatest quality but is less mess than the pots of grease and gets the job done. I always tape wires in place when I'm soldering as it can be hard to hold wire, solder and the iron all at once and in unison.

It may have been stated above or elsewhere but when soldering, please wear a mask or a respirator to block away any of those bad toxins that tend to otherwise end up inhaled. That shit will leave you with a bad buzz and a lower IQ at the end of the day.

Anything that can catch fire and comes close to LES will burn. We have seen paper and greengene's Tie burn if they within close proximity to COB.
Careful if you design any DIY reflector. Improperly mounted reflector can smoke or catch fire.

Secure solder and connection can avoid arcing. Proper gauge wire important too.
Wire sleeve can protect wires from shorting due to from abrasion, temperature.

If fan fails the COB overheats but can handle upto 110C, which is very high. At some higher temperature beyond that the cob pops and smokes its phosphorus on LES just before the connections within the cob burns out and circuit becomes open. I do not think it is as bad.

Most meanwell driver and made of flame retardant plastic case or metal case. As Supra suggested most cheepo driver work fine.

For people who are more than average paranoid.
Sunlight Flims presents this horror movie. Your friendly household rat eats your grow tent, sneeks into your grow tent, rolls up a joint, smokes and throws it in your grow room.



just kidding

Fire is my main concern in my grow space. It would lead to an awkward conversation with the fire and police departments.Neither of these organizations would share my enthusiasm for our horticultural hobby. My homeowners insurance company would take pleasure in explaining to me that because of the nature of my activities they would not settle a claim.
My wife of course would make the rest of my life as unbearable as she could. My tombstone would be inscribed with "this dickhead burned down our house".
After spending thousands on grow equipment a self activating fire extinguisher is a worthwhile investment for very little coin. Certainly cheaper than rebuilding a home from scratch.

Cheers,
Will

Fire safety is why I've spent thousands on LED over the past few years.

I have meanwell Hlg185H - C1400A and pre build from the shop 4 individual cob attacht with bjb holder on 136 mm heatisink.

How danger this is to catch a fire...
When light are working the heatsink goes really hot but other than that I cant see how aluminium can go on fire and catch my grow tent...Am I right?
I think the worst that can happen the fan and carbon filter from above can somehowe fall down to the light and than is really shit because the cobs will fall down from 1.5 meter to the ground..
What if this happen
The driver will continue working and then there is fire possibility??

Or second version that the air from clip fan some how disconnect the copper wire from bjb holder and the whole circut goes off but the driver continue working and sending power..???
What will happen then?