How much volt in the PSU case is normal

[burgerMan]

Hey!

I bought a new graphic cards some days ago and was going to switch to it in the PC when I sensed a tingeling electric feeling from the case.

I was already grounded through an ESD armband connected to the radiator, to not damage the graphic card.

Googled around and found out that it could be the PSU and ground issues, took my multimeter and checked the AC on the PSU in the case and outside, to be between 8v-15v.

Checked the ground and noticed that we do not have ground outlets in our apartment (have no idea how I could have missed this).

Googled to see what I could do and found out that the PSU should not let out any Volt from the case, even if it doesn't have a ground.

Bought another PSU and this one also had power coming out from it, although it was only 5v-6v this time.

I was planning to send the PSU back to warranty, because it shouldn't let out any power?

I am going to talk to my landlord and hopefully make him install grounded outlets.

Until then, using a power surge between the outlet and the computer.

 

The question is, have I understood this all correctly, that the PSU shouldn't leak any AC through its case, even when it doesn't have a ground?

Because it feels kinda crazy that both of these PSUs did have similar issues. Or if it is normal and I don't have to send back this PSU on warranty? Then, how much volt leaking until it is not normal then?

 

Thank you for reading and help and answers is appreciated, I am a noob in electricity!

[Levent]

Zero volts, your house electrical infrastructure has no grounding.

[BiotechBen]

If your electrical grid has zero grounding, it can theoretically, technically, use the case as a "dump to ground" like a tiny capacitor,  at low, "safe" voltage for ESD level current. HOWEVER, if your electrical system has ZERO grounding, you should not be touching things that are metal and plugged in to AC power.

[burgerMan]

25 minutes ago, Levent said:

Zero volts, your house electrical infrastructure has no grounding.

So I should send this PSU back through warranty then? Yes, the apartment only has ground in the kitchen area.

[Spotty]

24 minutes ago, burgerMan said:

Checked the ground and noticed that we do not have ground outlets in our apartment (have no idea how I could have missed this).

You should check what the regulations are for your country as many countries require power outlets in the home to be grounded. If the electrical standards in your country require it then whoever manages your apartment will need to fix it to meet regulations.

 

28 minutes ago, burgerMan said:

took my multimeter and checked the AC on the PSU in the case and outside, to be between 8v-15v.

You're probably measuring DC. Switch the multimeter to DC mode.

 

Just now, burgerMan said:

So I should send this PSU back through warranty then? Yes, the apartment only has ground in the kitchen area.

... No? The PSU isn't faulty. It's a problem with your house wiring not the power supply.

What were the two models of power supplies you bought?

[burgerMan]

12 minutes ago, BiotechBen said:

If your electrical grid has zero grounding, it can theoretically, technically, use the case as a "dump to ground" like a tiny capacitor,  at low, "safe" voltage for ESD level current. HOWEVER, if your electrical system has ZERO grounding, you should not be touching things that are metal and plugged in to AC power.

Hm okey, there is ground in the kitchen so there is not zero ground in the house, just not the other outlets than the kitchen.

Yes, I will try to keep away from touching the computer chassi.

I was more questioning if it really was that I got two PSUs that was faulty, because they let through Volt directly through the ground-case-chassi.

I guess it maybe is hard for people to know if this is normal because many people have grounded outlets and doesn't notice these volts escaping to the case.

[burgerMan]

6 minutes ago, Spotty said:

You should check what the regulations are for your country as many countries require power outlets in the home to be grounded. If the electrical standards in your country require it then whoever manages your apartment will need to fix it to meet regulations.

Checked now and here in Sweden it seems like that houses built after 1994 has to have grounded outlets but it doesn't seem to be law to change already ungrounded outlets.

 

7 minutes ago, Spotty said:

You're probably measuring DC. Switch the multimeter to DC mode.

Hm okey, I am not so good at understanding the difference, I have not checked DC mode, only AC.

 

8 minutes ago, Spotty said:

... No? The PSU isn't faulty. It's a problem with your house wiring not the power supply.

What were the two models of power supplies you bought?

 Then I am missing the point here..

Why is the PSU sending out volt through the ground if it shouldn't do that? Isn't because something is shorted or something like that?

Thanks for helping me

[manikyath]

if your house has no earthing, the voltage on the "ground" in your pc can float wherever it wants to be. i have a supposed "double insulated" device that is very much not (double insulated = does not need an earthed socket), and the case of that likes to float quite far into "tingles if you touch it" terretory.

 

you might want to look into what it'll take to add earthing to your house installation, it's there for your safety, not to pull dollarydoos out of your pocket.

 

something that does work for before mentioned device of mine, is to plug in the plug on the wall the other way around. normally all power supplies have some form of coupling to the mains to keep the floating to a safe maximum, but it has to couple to one side of the mains plug, so if you plug it in the wrong way it's now reference to the live wire, not the neutral wire... which causes before mentioned floating to happen quite notably.

 

Just now, burgerMan said:

Checked now and here in Sweden it seems like that houses built after 1994 has to have grounded outlets but it doesn't seem to be law to change already ungrounded outlets.

i presume laws there might be similar to laws here, and here it's not a requirement to change it, but you need to pass electrical inspection to sell the house (or fail inspection, and sell with a failed inspection), and you'll always fail if there's any non-earthed outlets at all.

 

so - in a sense - it affects the value of your house to the same degree as it would cost you to sort out earthing.

 

2 minutes ago, burgerMan said:

Then I am missing the point here..

Why is the PSU sending out volt through the ground if it shouldn't do that? Isn't because something is shorted or something like that?

Thanks for helping me

because without an earth connection, there is nothing for the PSU to reference itself to.

[Spotty]

6 minutes ago, burgerMan said:

 Then I am missing the point here..

Why is the PSU sending out volt through the ground if it shouldn't do that? Isn't because something is shorted or something like that?

Thanks for helping me

It's normal for power supplies to have a small amount of leakage current, a few mA maybe. It's usually caused by the EMI filtering on the PSU. Though there can be other causes for it such as a short to the case in the system.

While you have the multimeter out measure the current.

 

9 minutes ago, burgerMan said:

Checked now and here in Sweden it seems like that houses built after 1994 has to have grounded outlets but it doesn't seem to be law to change already ungrounded outlets.

If your kitchen has grounded outlets it should be possible for an electrician to connect the rest of the outlets in the apartment to ground. Assuming the kitchen outlets are actually earthed and not just GFCI outlets.

[burgerMan]

54 minutes ago, manikyath said:

because without an earth connection, there is nothing for the PSU to reference itself to.

"Reference itself to" could you explain that to me maybe?

[burgerMan]

43 minutes ago, Spotty said:

It's normal for power supplies to have a small amount of leakage current, a few mA maybe. It's usually caused by the EMI filtering on the PSU. Though there can be other causes for it such as a short to the case in the system.

While you have the multimeter out measure the current.

Ah okay, this is mostly what I was wondering about Thank you! Then I will not send back the PSU, or first check the current to see if it is more than a few mA.

The last part, "though there can be other causes for it such as a short to the case in the system." Is it anyway to know if it is a short or just "normal" leakage ? Maybe how much current that is leaking?

 

46 minutes ago, Spotty said:

If your kitchen has grounded outlets it should be possible for an electrician to connect the rest of the outlets in the apartment to ground. Assuming the kitchen outlets are actually earthed and not just GFCI outlets.

Yeah, I will try to have the landlord do this. I contacted him yesterday about it and he didn't know that the outlets were ungrounded either

[manikyath]

8 minutes ago, burgerMan said:

"Reference itself to" could you explain that to me maybe?

the voltage on the case you're measuring is the power supply's "zero proint", but without another zero point to compare itself to, it has no idea of how zero this zero point is.

 

it's like measuring the tallest mountain, without sea level as a reference.

[burgerMan]

33 minutes ago, manikyath said:

the voltage on the case you're measuring is the power supply's "zero proint", but without another zero point to compare itself to, it has no idea of how zero this zero point is.

 

it's like measuring the tallest mountain, without sea level as a reference.

Okay, if I understand you correctly, I did use a ground source when I was using the multimeter. I had one pronge on the radiator, which is grounded, and the other on the PSU case/screws/computer chassi.

But I will test the mA as Spotty suggested above, and see what that could show me.

Thank you all for the help! Great first experience here

[burgerMan]

On 1/9/2024 at 5:17 PM, manikyath said:

the voltage on the case you're measuring is the power supply's "zero proint", but without another zero point to compare itself to, it has no idea of how zero this zero point is.

 

it's like measuring the tallest mountain, without sea level as a reference.

Hey there again! Sorry for taking a while for answering.

I think I understand now what you meant with this, because the PSU is not connected to the ground, it doesn't matter if I use one multimeter pronged on the radiator, because it will not reach eachother?

I can use only one pronge on the PSU and get AC values.

I also tried the NCV and that alarmed fully.

Do you know any way I can measure the current on the PSU when it is connected to ground?

Should I just use both prongs on it?

[burgerMan]

On 1/9/2024 at 4:24 PM, Spotty said:

It's normal for power supplies to have a small amount of leakage current, a few mA maybe. It's usually caused by the EMI filtering on the PSU. Though there can be other causes for it such as a short to the case in the system.

While you have the multimeter out measure the current.

 

If your kitchen has grounded outlets it should be possible for an electrician to connect the rest of the outlets in the apartment to ground. Assuming the kitchen outlets are actually earthed and not just GFCI outlets.

Hey, I tried measuring current but it was zero.

Maybe because it is not connected to ground so I cannot multimeter it?

I tried the NCV option and that alarmed fully.

The only thing that is clear is that it is leaking AC somehow. And it seems to be leaking more than the newer PSU I bought.

Hard to know if that is normal for this old PSU or not..