Where the computer case get it's ground from the components and psu ground cable?

[Ngamer666]

Where the computer case get it's ground from the components and psu ground cable?

I understand the psu has the ground conductor, that's used through all the computer components but then where is usualy the point where it connects to the case chassis itself?

Most cases are painted or powdercoated, there must be somewhere in the case that's bare raw to connect to the ground of the components so that the case is grounded?

 

[BiotechBen]

7 minutes ago, Ngamer666 said:

Where the computer case get it's ground from the components and psu ground cable?

I understand the psu has the ground conductor, that's used through all the computer components but then where is usualy the point where it connects to the case chassis itself?

Most cases are painted or powdercoated, there must be somewhere in the case that's bare raw to connect to the ground of the components so that the case is grounded?

 

The area where the PSU screws into the case. As you screw it in it will scratch paint at minimum, and the threads are not going to be painted.

[kb5zue]

The grounding system inside the computer is an internal ground.  Every component inside your computer has a ground, fans have a ground, cd/dvd's have a ground, the video card has a ground.  Everything inside the computer has a ground and all those grounds are connected thru the system back to the PSU.  The PSU is connected to the earth ground thru the electrical wiring in your house.  So, as a result, everything in your system is also connected to earth ground, it just goes thru the internal wiring back to earth ground.

 

Also, if you're concerned about the case and the PSU together, check out the post above.  BioTechBen explains how the PSU and case are grounded together thru the PSU mounting screws.

Edited December 9, 2022 by kb5zue
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[Ngamer666]

2 minutes ago, BiotechBen said:

The area where the PSU screws into the case. As you screw it in it will scratch paint at minimum, and the threads are not going to be painted.

ah ok great, also the standoffs under the motherboard?

[Ngamer666]

Just now, kb5zue said:

The grounding system inside the computer is an internal ground.  Every component inside your computer has a ground, fans have a ground, cd/dvd's have a ground, the video card has a ground.  Everything inside the computer has a ground and all those grounds are connected thru the system back to the PSU.  The PSU is connected to the earth ground thru the electrical wiring in your house.  So, as a result, everything in your system is also connected to earth ground, it just goes thru the internal wiring back to earth ground.

yeah i know that, my question was about how it connect to the chassis itself

[BiotechBen]

Just now, Ngamer666 said:

ah ok great, also the standoffs under the motherboard?

Probably not, ground for motherboard goes back to PSU. 

[kb5zue]

2 minutes ago, BiotechBen said:

Probably not, ground for motherboard goes back to PSU. 

The motherboard standoffs are made of brass so they provide insulation between the motherboard and the case.  They don't conduct electricity.

[Ngamer666]

3 minutes ago, BiotechBen said:

Probably not, ground for motherboard goes back to PSU. 

hmmm if the case is grounded to the psu, then it's the same ground as the motherboard ground...

[Ngamer666]

Just now, kb5zue said:

The motherboard standoffs are made of brass so they provide insulation between the motherboard and the case.  They don't conduct electricity.

ah yes and now i remember they are often also painted.

[kb5zue]

I have never seen painted brass standoffs but if they are painted, that could pose a problem because the user doesn't know what type of paint was used.  Some paint can conduct current so painting the standoffs would pose a problem if they were painted with current conducting paint.  The best thing to do with painted standoffs is not use them, use the standard brass standoffs that come in the same box as the motherboard.

[Ngamer666]

3 minutes ago, kb5zue said:

I have never seen painted brass standoffs but if they are painted, that could pose a problem because the user doesn't know what type of paint was used.  Some paint can conduct current so painting the standoffs would pose a problem if they were painted with current conducting paint.  The best thing to do with painted standoffs is not use them, use the standard brass standoffs that come in the same box as the motherboard.

well i mean, they are black in my case, maybe not painted but something else, i dont think the bare material of theses standoff is black

[Lurking]

It is grounded through the PSU case. But as you noticed, due to paint it isn't a perfect bond. Technically they should use screws that scrape into the metal. So it will have some resistance. But that is fine, outside the PSU you only have low voltage. And the PSU is grounded well through the receptacle assuming your building ground is good (which is not a given!).

[Ngamer666]

ok thanks guys i'll check if the psu screws are getting ground to the rest of the case through them

 

[NF-A12x25]

12 minutes ago, kb5zue said:

The motherboard standoffs are made of brass so they provide insulation between the motherboard and the case.  They don't conduct electricity.

what are you on brass is not an insulator my dude 

[NF-A12x25]

11 minutes ago, kb5zue said:

I have never seen painted brass standoffs but if they are painted, that could pose a problem because the user doesn't know what type of paint was used.  Some paint can conduct current so painting the standoffs would pose a problem if they were painted with current conducting paint.  The best thing to do with painted standoffs is not use them, use the standard brass standoffs that come in the same box as the motherboard.

wtf this is just dumb first of all since when do motherboard standoffs come in the same box as the motherboard, second of all standoffs are not meant to be an insulator at all and are made of conductive material most of the time, and it’s also often not brass (which does conduct electricity) but steel (which also conducts electricity)

[kb5zue]

3 minutes ago, Ngamer666 said:

well i mean, they are black in my case, maybe not painted but something else, i dont think the bare material of theses standoff is black

Now you have my curiosity piqued because I have never seen painted standoffs that came with the case.  Did you get the case new or get it from a 3rd party.  Were the painted standoffs included with the case when purchased or did you buy them separate?  I'm just really curious about how the painted standoffs got installed in the case because I know that when you buy a new motherboard they all come with brass, non-painted, screws.  So how did you end up with black painted standoffs instead?

[Ngamer666]

2 minutes ago, NF-A12x25 said:

what are you on brass is not an insulator my dude 

yeah i tested continuity with my brass standoffs i use for something else, they are definetely conductive, but the ones in my case are not the same they are black covered by something

[Ngamer666]

Just now, kb5zue said:

Now you have my curiosity piqued because I have never seen painted standoffs that came with the case.  Did you get the case new or get it from a 3rd party.  Were the painted standoffs included with the case when purchased or did you buy them separate?  I'm just really curious about how the painted standoffs got installed in the case because I know that when you buy a new motherboard they all come with brass, non-painted, screws.  So how did you end up with black painted standoffs instead?

It's the ones that are pre installed in my fractal case, i'm pretty sure they were black, all the inside is black

[kb5zue]

3 minutes ago, NF-A12x25 said:

what are you on brass is not an insulator my dude 

Okay, not completely non-conductive but close enough they provide an insulation.  Here is the most recent information concerning brass and current flow.

 

Brass is only 28% as conductive as copper. Some bronzes are as low as 7% as conductive as copper! Copper is the standard by which electrical materials are rated and conductivity ratings are expressed as a relative measurement to copper.

[Ngamer666]

2 minutes ago, kb5zue said:

Now you have my curiosity piqued because I have never seen painted standoffs that came with the case.  Did you get the case new or get it from a 3rd party.  Were the painted standoffs included with the case when purchased or did you buy them separate?  I'm just really curious about how the painted standoffs got installed in the case because I know that when you buy a new motherboard they all come with brass, non-painted, screws.  So how did you end up with black painted standoffs instead?

[NF-A12x25]

Just now, kb5zue said:

Okay, not completely non-conductive but close enough they provide an insulation.  Here is the most recent information concerning brass and current flow.

 

Brass is only 28% as conductive as copper. Some bronzes are as low as 7% as conductive as copper! Copper is the standard by which electrical materials are rated and conductivity ratings are expressed as a relative measurement to copper.

that is not how that works

 

Brass and bronze are still very conductive, just not as conductive as copper. They do not provide an insulation in the slightest. Please stop spreading misinformation.

[Ngamer666]

Just now, kb5zue said:

Okay, not completely non-conductive but close enough they provide an insulation.  Here is the most recent information concerning brass and current flow.

 

Brass is only 28% as conductive as copper. Some bronzes are as low as 7% as conductive as copper! Copper is the standard by which electrical materials are rated and conductivity ratings are expressed as a relative measurement to copper.

I tested multimeter conductivity, the brass not coated ones i have for other stuff i build are definetely very conductivelol

[NF-A12x25]

4 minutes ago, kb5zue said:

I'm just really curious about how the painted standoffs got installed in the case because I know that when you buy a new motherboard they all come with brass, non-painted, screws.

also not true  motherboards do not come with case standoffs ever. 

[Ngamer666]

Just now, NF-A12x25 said:

also not true  motherboards do not come with case standoffs ever. 

yeah the last 2 pc case i bought were all black standoff, thats probably coated with something, the only one i remember that were brass color dates from at least 15 years ago with the ugly gray old cases

[Ngamer666]

2 minutes ago, NF-A12x25 said:

also not true  motherboards do not come with case standoffs ever. 

yes both my fractal cases had pre installed standoff for the motherboard, i built one this month and i remember it clearly