Power brick failure : 500 ohm between phase (or neutral) and earth

[srb1954]

You want hard proof they have safety approvals, always ask for the product's certificate.
P.S. - where is this thing's fuse? First thing to look for.

I checked it has a proper fuse inside heatshrink tube.
The capacitor between primary and secondary is jd222my1. 400V rated but I don't know if it's a proper safety one with the peak handling of several kV

If it is a proper safety capacitor it would be marked as Class Y and have various symbols printed on it attesting to it having been approved by various safety authorities.

But, then there is the question if those markings are genuine or not or whether it is even a counterfeit capacitor.

[thm_w]

A few failed parts is not really a "huge deal, return everything to the supplier" issue as people are making it out to be. Its completely normal even with western companies. Until we get some actual proof of intentional poor construction.

Which leads me to the question, why are these tripping the mains breaker? Shouldn't they have an internal fuse? I would have assumed that is a requirement for these.
Maybe check that the mains lead is wired correctly, and that there is some fuse or fusible resistor on that board.

[Monkeh]

A few failed parts is not really a "huge deal, return everything to the supplier" issue as people are making it out to be. Its completely normal even with western companies. Until we get some actual proof of intentional poor construction.

Which leads me to the question, why are these tripping the mains breaker? Shouldn't they have an internal fuse? I would have assumed that is a requirement for these.
Maybe check that the mains lead is wired correctly, and that there is some fuse or fusible resistor on that board.

RCD (GFCI).

[bdunham7]

A few failed parts is not really a "huge deal, return everything to the supplier" issue as people are making it out to be.

It depends on the failure.  1 out of 200 "just don't work"?  OK, warranty replacement.  1 out of 2000 bursts into flames or 1 out of 200000 electrocutes the user on the first use?  Total product recall. 

[ratatax]

A few failed parts is not really a "huge deal, return everything to the supplier" issue as people are making it out to be. Its completely normal even with western companies. Until we get some actual proof of intentional poor construction.

The only threat I can see is if one of my customer get a defective unit AND for some reason has no earth connection in his house. The heatsink is at 100+VDC and gets connected to the negative output terminal if that earth wire touches it (then I don't know if the PSU destroys itself or keeps a dangerous voltage at the output)

It shouldn't be possible to plug my power supply into an earth-less outlet, since it has that prong that will only fit earthed sockets.
So imagine if some accident occurs, who is liable ? Me because the power supply is defective, or the customer because his electrical installation isn't right ?

[bdunham7]

So imagine if some accident occurs, who is liable ? Me because the power supply is defective, or the customer because his electrical installation isn't right ?

I rarely venture any legal advice outside my home territory, but I'm pretty sure you'd be liable and you'd have other issues as well, like the product non-conformity.  And if it were shown that you previously knew about the defect or non-conformity, you might have criminal liability in some jurisdictions.

[ratatax]

I could test the faulty unit without the earth connection, to see what's the failure mode in case that very rare case happens (blown fuse ? boom ? flames ?), but even if I take every measure to do it safely I'm not very comfortable doing that experiment

[bdunham7]

I could test the faulty unit without the earth connection, to see what's the failure mode in case that very rare case happens (blown fuse ? boom ? flames ?), but even if I take every measure to do it safely I'm not very comfortable doing that experiment

Well than I'd hope that you would be equally uncomfortable shipping the units as-is for your customers to do the experiment themselves!  I would assume that even if it doesn't combust, the defect would cause the output to be at high voltage relative to ground if the power plug were not earthed.

It's a crappy deal and TBH, I think it is likely that the vast majority of the non-failed devices are just fine.  If it were me I'd sleep better if I could at least X-ray them.  Have you notified your supplier of this issue?

[thm_w]

A few failed parts is not really a "huge deal, return everything to the supplier" issue as people are making it out to be.

It depends on the failure.  1 out of 200 "just don't work"?  OK, warranty replacement.  1 out of 2000 bursts into flames or 1 out of 200000 electrocutes the user on the first use?  Total product recall.

The output is earth grounded in this case, its not going to electrocute the user.

[ratatax]

I could test the faulty unit without the earth connection, to see what's the failure mode in case that very rare case happens (blown fuse ? boom ? flames ?), but even if I take every measure to do it safely I'm not very comfortable doing that experiment

Well than I'd hope that you would be equally uncomfortable shipping the units as-is for your customers to do the experiment themselves!  I would assume that even if it doesn't combust, the defect would cause the output to be at high voltage relative to ground if the power plug were not earthed.

It's a crappy deal and TBH, I think it is likely that the vast majority of the non-failed devices are just fine.  If it were me I'd sleep better if I could at least X-ray them.  Have you notified your supplier of this issue?

I don't know anyone with an Xray machine, but that would be very interesting to see how frequent is that wire issue.
I notified the supplier and am waiting for his response.

[jonpaul]

don't buy cheap ChiCom junk in a safety related device

j

[bdunham7]

The output is earth grounded in this case, its not going to electrocute the user.

The question was what happens when the device is plugged into a socket that doesn't have a working ground.

[wraper]

IMHO failure happened during enclosure welding. If you are intending to keep them, inspect all PSUs if they don't have a slight bulge in heatsink area. Maybe try pressing on enclosure and see if plastic can be pushed inside slightly on OK units. This way you could find bad ones without taking apart. Also certainly get an insulation tester like this https://www.tme.eu/en/details/ut512/insulation-resistance-meters/uni-t/ and check them all. I also suggest taking apart a transformer to check if there is a sufficient insulation between windings.

[wraper]

The output is earth grounded in this case, its not going to electrocute the user.

The question was what happens when the device is plugged into a socket that doesn't have a working ground.

Yes, absence of earth is way too common, especially in older houses.

[wraper]

It shouldn't be possible to plug my power supply into an earth-less outlet, since it has that prong that will only fit earthed sockets.
So imagine if some accident occurs, who is liable ? Me because the power supply is defective, or the customer because his electrical installation isn't right ?

From your profile you're in France where they have no Earth prong on the plug side. As of Europe and many other places, unearthed sockets (Type C) accept earthed Schuko plugs. Also many older houses have earthed sockets installed but no actual earth connection. Not to say user can bring the device to other country and replace the cable.

[Zero999]

A few failed parts is not really a "huge deal, return everything to the supplier" issue as people are making it out to be. Its completely normal even with western companies. Until we get some actual proof of intentional poor construction.

A failure which results in the output being connected to mains is a big deal. As mentioned above, unearthed sockets are all too common. It should be designed not to give someone a dangerous shock, even if it is plugged into an unearthed socket.

I could test the faulty unit without the earth connection, to see what's the failure mode in case that very rare case happens (blown fuse ? boom ? flames ?), but even if I take every measure to do it safely I'm not very comfortable doing that experiment

Well than I'd hope that you would be equally uncomfortable shipping the units as-is for your customers to do the experiment themselves!  I would assume that even if it doesn't combust, the defect would cause the output to be at high voltage relative to ground if the power plug were not earthed.

It's a crappy deal and TBH, I think it is likely that the vast majority of the non-failed devices are just fine.  If it were me I'd sleep better if I could at least X-ray them.  Have you notified your supplier of this issue?

I don't know anyone with an Xray machine, but that would be very interesting to see how frequent is that wire issue.
I notified the supplier and am waiting for his response.

There is no way to test for this, because the insulation on the earth might fail during use.

You could potentially open them all up and rectify the fault, by ensuring the earth wire is in the cut-out and is properly protected from abrasion, but is it worth your time?

[wraper]

There is no way to test for this, because the insulation on the earth might fail during use.

You could potentially open them all up and rectify the fault, by ensuring the earth wire is in the cut-out and is properly protected from abrasion, but is it worth your time?

X-Ray will show dislocated wire. Also you could look for a bulge on enclosure. If insulation is pierced but wire is not making connection Hi-pot testing will show it too.

[ratatax]

It shouldn't be possible to plug my power supply into an earth-less outlet, since it has that prong that will only fit earthed sockets.
So imagine if some accident occurs, who is liable ? Me because the power supply is defective, or the customer because his electrical installation isn't right ?

From your profile you're in France where they have no Earth prong on the plug side. As of Europe and many other places, unearthed sockets (Type C) accept earthed Schuko plugs. Also many older houses have earthed sockets installed but no actual earth connection. Not to say user can bring the device to other country and replace the cable.

The only problem is if earthed sockets are installed but not connected. Replacing the cable won't allow them to get rid of earth (IEC 3-pong, it always comes with an earthed plug on the other end, and these wont' fit into Type-C outlets, they really only fit into earthed ones like type F or type E).

You could potentially open them all up and rectify the fault, by ensuring the earth wire is in the cut-out and is properly protected from abrasion, but is it worth your time?

Abrasion cannot happen really if it's inside the cut-out. Wire is fairly rigid and the heatsink is thick.

I checked for bulges but I can't see anything and I can press on the faulty unit without problems. I think the wire got squeezed when the "press" assemble the units. Once it's assembled, there is some tolerance between the case height and the heatsink (heatsink = 23mm high, while i measured the inside case at 23.5mm, just enough place for the copper wire once the insulation is cut)

[wraper]

The only problem is if earthed sockets are installed but not connected. Replacing the cable won't allow them to get rid of earth (IEC 3-pong, it always comes with an earthed plug on the other end, and these wont' fit into Type-C outlets, they really only fit into earthed ones like type F or type E).

What? Any plug that fits into earthed type F/E socket will also fit into unearthed type C. There are compatibility problems between type F and E unless plug is made universal to fit both socket types but any type E and F plug will fit into type C socket.
https://en.wikipedia.org/wiki/CEE_7_standard_AC_plugs_and_sockets

[wraper]

Another method how to check these came to my mind. You could pass high current from the mains earth terminal to negative output and look with somewhat decent IR camera. If wire is jammed it will be closer to enclosure and in the wrong location. So hotspot in a wrong place should be noticeable.
Again, don't even think shipping these to your customers without checking every unit with insulation tester with at least 2.5kV test voltage.

[ratatax]

Thanks I will buy that UNI-T insulation tester. At the end, no matter how is the wire, if it survives high voltage insulation test then it's fine.
I have an IR camera but I need a REALLY high current to make such a thick wire to warm up and warm the plastic case around it

[ratatax]

The only problem is if earthed sockets are installed but not connected. Replacing the cable won't allow them to get rid of earth (IEC 3-pong, it always comes with an earthed plug on the other end, and these wont' fit into Type-C outlets, they really only fit into earthed ones like type F or type E).

What? Any plug that fits into earthed type F/E socket will also fit into unearthed type C. There are compatibility problems between type F and E unless plug is made universal to fit both socket types but any type E and F plug will fit into type C socket.
https://en.wikipedia.org/wiki/CEE_7_standard_AC_plugs_and_sockets

Yes sorry I was wrong on that

[thm_w]

Another method how to check these came to my mind. You could pass high current from the mains earth terminal to negative output and look with somewhat decent IR camera. If wire is jammed it will be closer to enclosure and in the wrong location. So hotspot in a wrong place should be noticeable.
Again, don't even think shipping these to your customers without checking every unit with insulation tester with at least 2.5kV test voltage.

Hopefully the device has no L-E MOVs, and OP can tie L-N together then hi-pot to earth at 2.5kV.

Thanks I will buy that UNI-T insulation tester. At the end, no matter how is the wire, if it survives high voltage insulation test then it's fine.
I have an IR camera but I need a REALLY high current to make such a thick wire to warm up and warm the plastic case around it

Yeah I can't really see that working.

[thm_w]

BTW ratatax, how much are you paying per adapter? How many watts?

[ratatax]

Adapters are 24W (12V 2A). They cost me about $4.4 per unit