New cob light power cord melting!!

Hi all I'm in dire need of help.I have finally got my first cob light, it's a johnson grow light cx-9 (Johnson Grow Lights is now Horticulture Lighting Group...I'm sure many of you are familiar with them) It is a 9 cob cxa3070 light. I bought it used off eBay and it cane with 2 replacement fans as 2 of them had burnt out and he had contacted HLG about it and they sent him replacements. Apparently he moved and was unable to continue growing. He claimed to have only used the light for one bloom cycle or less than 2000 hours. I received the light and replaced the fans. Everything seemed to be in perfect working order so I hooked it up in my flower tent. I didn't want to shock my plants with too much new light right off the bat so I initially only turned on 5 of the 9 cobs. That was yesterday...now this morning I went to check on it and everything looked good and plants seemed to enjoy the new light so I turned on the rest of the cobs. Luckily for me I didn't leave right away but was looking over the girls and checkin out bud development when I noticed smoke blowing around the tent. Once I figured out what it was I tried to unplug the power cord from the light and it burned the crap out of my hand but I was kinda freaking out. The power cord melted mainly in a spot where it was being held up along the roof and away from the plants. The point of contact to the strap holding it up completely melted through the insulation. Can someon PLEAS help me understand what may have caused this? I noticed that the cord seemed kinda flimsy for the amperage of this light which I believe is in the mid 5's. My power cords for my blurples are quite a bit sturdier so that's what initially drew my attention. Could this be the simple? I've written the seller to ask if he switched out the power cord for some reason but haven't received a reply yet and I'm completely freaked out so I thought I ask the good people on here for help. One other thing I'd like to mention is that in order to open up the light to replace the fans I had to disconnect all the cobs from the drivers. The wires running from the drivers to the cobs all had a clip that you have to disconnect in order to remove the lights housing as the lights are connected to one side and the drivers and fans to the other. There is one driver per cob and I was wondering if maybe I plugged them back in in the wrong order or something to possibly cause this problem? Seems unlikely to me but I admittedly know very little about this stuff. The fans were just clips so it wasn't something that involved any technical knowledge, that's why I felt comfortable replacing them myself. All I did was snip the wires to the bad fans and reconnect them to the clips on the new fans, so I don't think there's any problem there. I imagine that if I were to have crossed the wires (in the event the colors weren't supposed to match or something? By this I mean that I shouldn't have connected the red to red and black to black) Then I assume the fans wpuldnt have functioned but I tested them prior to installing rhe lighg in the tent and they were on.
That's all the info in the can think to include. If I missed anything feel free to ask any questions you may have, and thank you in advance.

Here's a picture of the melted spot of the cord and the light. Though the entire cord was melting. I believe that if it had been left on for another minute the entire cord would have melted.

Pretty sure you only need a better cable with thicker wire diameter. For a 500w light the powercord should have awg18 or 1,5mm² wires inside. Pretty sure your cable is less than 0,5mm² diameter or so and therefor gets too hot when running up to 5 Amps thru it.
This sometimes happens when a reseller like xxx.growlights.com purchase lots of lamps and choosed to buy them without powercords to keep the price as low as possible.
They use own powercords and this can sometimes be of bad quality.

If something would be wrong with the wiring/repair either something should not work(a COB or fan) or it should trigger the braker in case of a short. So I'm pretty sure all you need is a quality cable.
If I remember that correctly it already happend one or two years back with exact the same light. He got a new one and the issues were gone!

Randomblame said:

Pretty sure you only need a better cable with thicker wire diameter. For a 500w light the powercord should have awg18 or 1,5mm² wires inside. Pretty sure your cable is less than 0,5mm² diameter or so and therefor gets too hot when running up to 5 Amps thru it.
This sometimes happens when a reseller like xxx.growlights.com purchase lots of lamps and choosed to buy them without powercords to keep the price as low as possible.
They use own powercords and this can sometimes be of bad quality.

If something would be wrong with the wiring/repair either something should not work(a COB or fan) or it should trigger the braker in case of a short. So I'm pretty sure all you need is a quality cable.
If I remember that correctly it already happend one or two years back with exact the same light. He got a new one and the issues were gone!

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Wow I sure b hope your right! This is stressing me out. I keep thinking what if I would've left. My poor girls would've burned to death in the wrong way!! Haha. No seriously tho I can't even start to contemplate my house burning down. Ugh.

Bestg4202 said:

Wow I sure b hope your right! This is stressing me out. I keep thinking what if I would've left. My poor girls would've burned to death in the wrong way!! Haha. No seriously tho I can't even start to contemplate my house burning down. Ugh.

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I think it's criminal that reseller supply lowest quality cables in order to save a few cents. At least negligent! One should sue them ..

Johnson growlights use meanwells don’t they? I think it’s probably a knock off.

First file a complaint with ebay . Contact seller and tell him you want to return it and he needs to pay shipping since his shotty rewiring of the fans almost burnt down your house. Make sure you stay on top of the complaint they expire after so many days, seller will try to use this to their advantage. Don't leave a feed back until the issue is resolved. You can use the feedback as a bargaining tool with the seller. If you leave a bad feedback before your issue is resolved the seller more then likely wont work with you. Good luck.

Stop using it immediately until you get it fixed. If the wires are even so much as warm, it's a fire waiting to happen. ( I guess this is obvious, but I feel like I need to say it anyway)

Yeah, definitely sounds like an underspecd power cord........... lucky you caught it.

Hlg should help you out?, it's Stephen,'s light..... and have good CS. Worth a try before purchasing a beefier cord.

God luck

PSUAGRO. said:

Yeah, definitely sounds like an underspecd power cord........... lucky you caught it.

Hlg should help you out?, it's Stephen,'s light..... and have good CS. Worth a try before purchasing a beefier cord.

God luck

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Ya they've been great so far. I've actually asked them like 6-8 questions and they were a great help. They have awesome customer service to be dealing with some dude who bought one of there products 2nd hand. I did email em about the cord too just to ask em for recommendations. And the previous post on here about knock offs got me all worried that I got ripped off because it doesn't have meanwell drivers. I'm still waiting for a reply though.

Randomblame said:

I think it's criminal that reseller supply lowest quality cables in order to save a few cents. At least negligent! One should sue them ..

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I agree...If I knew that he actually bought the light for the purpose of resell I'd be extremely pissed off. But from what he says he bought it to grow with and ended up not being able to use it. I still don't understand why he switched out the power cord though if that was the case. Because who says "ooo this is a nive power cord, I think I'll keep this one and throw in this cheapo I have layin around!" That just doesn't make sense.
I can't even imagine what would've happenned if I would've left...cuz I was actually running late for an appointment but I decided to give all tge lower buds a once over to check for nanners. I had some on my last run and now I'm all parinoid about it. So that whole chain of events had to happen just right for me not to have started a house fire. And if I left the house completely there's a really good chance the whole house would've went up.

Randomblame said:

Pretty sure you only need a better cable with thicker wire diameter. For a 500w light the powercord should have awg18 or 1,5mm² wires inside. Pretty sure your cable is less than 0,5mm² diameter or so and therefor gets too hot when running up to 5 Amps thru it.
This sometimes happens when a reseller like xxx.growlights.com purchase lots of lamps and choosed to buy them without powercords to keep the price as low as possible.
They use own powercords and this can sometimes be of bad quality.

If something would be wrong with the wiring/repair either something should not work(a COB or fan) or it should trigger the braker in case of a short. So I'm pretty sure all you need is a quality cable.
If I remember that correctly it already happend one or two years back with exact the same light. He got a new one and the issues were gone!

Click to expand...

Thanks for your help. The seller said that he'll send me a different cord and he tried to convince me that the only difference between different cords is the amount of insulation....that's incorrect right? More insulation does NOTHING to change the amount n if resistance...so why the f*** would more insulation help in any way. Ugh. It's really hard to stay cordial with this guy but I am. I'm gonna wait till I get the replacement cord and then tell him politely that he needs to learn from this and not do stupid sh** just to save a couple bucks. And I really wanna document it somehow so that if it ever happens to someone else from this guy that they know it's not the first time.

Power cords come in different gauge wire, But @ 500 watts 4 amps even a thin wired one should not have melted like that. I would have the fixture looked at by a electronics expert if your not going to return it before using it. Here is a 14 awg power cord rated @ 15 amps you can also get 12 awg cord that are rated @ 20 amps. https://www.amazon.com/Tripp-Lite-Computer-IEC-320-C13-P007-010/dp/B0027JRMD0/ref=pd_sim_147_9?_encoding=UTF8&pd_rd_i=B0012EI6KE&pd_rd_r=SGVC91WQN9ZC11E0AAA1&pd_rd_w=B8mIZ&pd_rd_wg=G84AT&refRID=SGVC91WQN9ZC11E0AAA1&th=1

Bestg4202 said:

More insulation does NOTHING to change the amount n if resistance...so why the f*** would more insulation help in any way.

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Better insulation would help if you were using higher voltages. You have it right. It would do nothing to prevent this problem.

Bestg4202 said:

I still don't understand why he switched out the power cord

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Not that this has much relevance to what happened...... but at some point did the original owner cut the original power cord off, in order to replace it with a cord to run it on 240? Then lose the original, replace it with a crappy 120 plug for resale?

It is out of sheer, arbitrary curiosity that I also wonder If, and why the original cord was removed....

Unfortunately I do not know much about the internal wiring of this particular light. Does it have one or two large HLG drivers or does each COB have its own driver? Is the light properly grounded or not?
The inrush current for instance can be significantly higher than 4Amps for a short time when 9 drivers start at the same time.
But I think it was a broken cable with a too thin "spot". AWG16 should be able to withstand much more current. Perhaps most of the wire strands were broken on this "spot", so that the current at this point had only a few intact strands to flow thru. That would explain why it only melted in one spot and not along the whole length. If the current is too high not only a short piece of the wire would be hot, but the whole wire would be.

Bestg4202 said:

I agree...If I knew that he actually bought the light for the purpose of resell I'd be extremely pissed off. But from what he says he bought it to grow with and ended up not being able to use it. I still don't understand why he switched out the power cord though if that was the case. Because who says "ooo this is a nive power cord, I think I'll keep this one and throw in this cheapo I have layin around!" That just doesn't make sense.
I can't even imagine what would've happenned if I would've left...cuz I was actually running late for an appointment but I decided to give all tge lower buds a once over to check for nanners. I had some on my last run and now I'm all parinoid about it. So that whole chain of events had to happen just right for me not to have started a house fire. And if I left the house completely there's a really good chance the whole house would've went up.

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No, no, I meant the dealer where he bought it first. These will buy often hundreds of cables for cheap and put them to all their lamps they sell. With low quality cables defects are not rare ...

Randomblame said:

Unfortunately I do not know much about the internal wiring of this particular light. Does it have one or two large HLG drivers or does each COB have its own driver? Is the light properly grounded or not?
The inrush current for instance can be significantly higher than 4Amps for a short time when 9 drivers start at the same time.
But I think it was a broken cable with a too thin "spot". AWG16 should be able to withstand much more current. Perhaps most of the wire strands were broken on this "spot", so that the current at this point had only a few intact strands to flow thru. That would explain why it only melted in one spot and not along the whole length. If the current is too high not only a short piece of the wire would be hot, but the whole wire would be.

Click to expand...

It was the whole wire....that point of contact pressure was just where it was actually catching fire. When I reach to try and unplug it, it burnt the crap out of me...I have a nice blister from it just now healing.

Randomblame said:

Unfortunately I do not know much about the internal wiring of this particular light. Does it have one or two large HLG drivers or does each COB have its own driver? Is the light properly grounded or not?
The inrush current for instance can be significantly higher than 4Amps for a short time when 9 drivers start at the same time.
But I think it was a broken cable with a too thin "spot". AWG16 should be able to withstand much more current. Perhaps most of the wire strands were broken on this "spot", so that the current at this point had only a few intact strands to flow thru. That would explain why it only melted in one spot and not along the whole length. If the current is too high not only a short piece of the wire would be hot, but the whole wire would be.

Click to expand...

It's one driver per cob. So 9. And ya I'm really curious about why he switched the cord as well but he never responded to that particular question .

JavaCo said:

Power cords come in different gauge wire, But @ 500 watts 4 amps even a thin wired one should not have melted like that. I would have the fixture looked at by a electronics expert if your not going to return it before using it. Here is a 14 awg power cord rated @ 15 amps you can also get 12 awg cord that are rated @ 20 amps. https://www.amazon.com/Tripp-Lite-Computer-IEC-320-C13-P007-010/dp/B0027JRMD0/ref=pd_sim_147_9?_encoding=UTF8&pd_rd_i=B0012EI6KE&pd_rd_r=SGVC91WQN9ZC11E0AAA1&pd_rd_w=B8mIZ&pd_rd_wg=G84AT&refRID=SGVC91WQN9ZC11E0AAA1&th=1

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Thanks man! I contacted HLG and they said 16awg is preferred but that 18 would be fine. The thing that's worrying me is that the cord that melted was 18....but ut was very flimsy feeling. An hour ago I used another 18awg that came with one of my Chinese blurples lights and started at 40% for 10 min...nothing so went to 60....nothing...then ran it on full power for about 5 minutes and the cord was fine...it might have been mildly warn but honestly I couldn't even tell if that was in my head...so if it was warm it was very mild. Either way I ordered a 16 awg and am only gonna run it at 40% till I get that one. Thanks for your help tho man, that's was nice of you to take the time to help out a stranger like that....much appreciated. Keep it irie bro íÍ'•}_,,~