Why does plugging in a PSU to ground your PC help during a build?

Luke876 · Mar 9, 2015

I don't actually understand how this helps.

Doesn't touching an unpainted part of the case suffice? It equalizes any differential between you and the case, and any static shock upon touching the case isn't going to damage components if you aren't touching them.

So why bother grounding the PC by plugging it in?

mamasan2000 · Mar 9, 2015

Never done that, I'd rather not have any electricity running while playing with the components.

So I touch the case...the beautiful, sexy case with the smooth lines and...

Mr5oh · Mar 9, 2015

So that will prevent you from shocking the case, but what about grabbing a board that is not in the case? I've always plugged in the PSU, then there is no doubt I am grounded.

Luke876 · Mar 9, 2015

mamasan2000 :

You turn the mains off and the PSU. Two switches at the OFF position, so you aren't at risk.

Mr5oh :

What? If I plug my PSU in then I understand my case is grounded. I attach a wrist strap to the case and both myself and my case are grounded... but why is it better to be grounded than to just touch unpainted metal on the case instead before picking components up?

I thought that if you touch the case and electrostatic discharge occurs then it only damaged the case and not the components, this is why people recommend you touch the case before picking up components... but if this is true then why do some say you should ground the case by plugging it in too, why isn't simply touching the case enough?

Unolocogringo · Mar 9, 2015

I have always plugged the power supply in and turned it off.
On the older style without a on/off switch, I plug them into a switched bus bar and turn it off.

Either way the case is grounded and no power present inside the case.
It removes static instead of equalizing it when you touch the case, so when you reach for the next component to install you have zero static electricity.
We all have our little quirks and this is one of mine. Others may agree or disagree, but as a electrician I would rather have zero static electricity instead of equalized static electricity.

A friend of mine was severely injured while pulling new power lines. Unknown to him the ground for the spool truck was not connected.
The static build up in the line from being pulled through all of the pulleys etc... had created enough static that when he reached for the end of the line to disconnect the pull rope it entered his hand and traveled down his arm and spine and exited the rear of his leg. Taking most of his calf muscles with it.
Needless to say he is now paralyzed , from the chest down. With limited minimal use of his right arm.

Mr5oh · Mar 9, 2015

I'm confused on what you are asking? I don't use a wrist strap, I just plug the power supply in and touch something bare metal?

Unolocogringo · Mar 9, 2015

If the case is not grounded by the power supply or the surface it is sitting on the static is equalized between you and the case, but static is still present.
If the case is grounded then every time you touch it the static is completely removed.
If you are wearing a wrist strap attached to a grounded case then static never has a chance to build up.

Luke876 · Mar 10, 2015

Unolocogringo :

Yep, I get that plugging in grounds the case. But at the end of the day if I am still moonwalking around the carpet and building up a huge charge, won't touching the grounded case still cause ESD, just like touching a case that hasn't been grounded would?

In other words, if I am charged then doesn't this trigger ESD despite the object I touch being grounded?

Unolocogringo · Mar 10, 2015

The case being grounded gives the discharge a direct path to ground . usually a copper or galvanized coated 8ft long steel rod driven into the soil near your meter box.
Electricity will travel along the path of least resistance, which would be steel case, power supply case, also steel down the ground wire to the outside ground rod.
If a case is not grounded you will not get a spike discharge, the static will equalize between your body and the case. Meaning you and the case now have an equal static charge.
I usually build on top of a motherboard or case box to prevent blemishes in the case exterior while working, this isolates the case away from any ground source.

Luke876 · Mar 10, 2015

Unolocogringo :

So are you saying that if I am holding a high amount of charge and touch a component in my grounded PC case, the ESD will not damage the components as much as if I were to touch a component within a non-grounded PC case?

It's a simple question but I'm struggling to find the answer still. You can ground a case but if you aren't grounding yourself then surely ESD can just as easily occur?

Unolocogringo · Mar 10, 2015

not what I am saying at all.
If the case is grounded and you discharge static into a component ,the static charge will travel through the component, through the motherboard traces ,up the ATX 12v or 20/24 pic connector to the power supply to ground.
If the case is not grounded, there will be no static discharge.

Grounding the case does not prevent you from building up a static charge. It gives you a convenient place to discharge the static charge in your body.

If you are wearing a static bracelet attached to the case that is grounded then static can not build up as you are always grounded.

Luke876 · Mar 10, 2015

Unolocogringo :

Then why do I still experience an electric shock (ESD) when I touch a metal sink or other grounded objects? If I have built up a high charge then touching a PC component is going to create ESD regardless of if that component is part of a grounded PC case?

I always thought that if you are electric shocked by the case then the ESD is like a 'lightning bolt' and only affects that part of the case you touched? This is why people say you should touch your case before handling the component. If the electricity went through the case and components this would not be good...

Mr5oh · Mar 10, 2015

The shock is the static discharging, if the case is properly grounded, this shock is discharged safely. It's electricity, if it's not grounded, it can travel to other things, not just the item you touched.

Luke876 · Mar 10, 2015

Mr5oh :

Then why do people recommend touching your case beforehand, if ESD is still going to invariably end up traveling to the components of an ungrounded case?

Steve Bloomfield · Mar 10, 2015

I watched a couple of youtube videos on this, its common sense really... Here's the links...

http://youtu.be/ubZuSZYVBng
http://youtu.be/AhlyMdiLc0E

Im sure if you look on youtube there is plenty more, but these both give you an insight into static charges

Unolocogringo · Mar 10, 2015

Minor Static build up is not damaging to components. It is spread out over a large area with a minute amperage.
The feeling of shock you get is when all of the static from you body concentrates in one area during discharge, increasing amperage as it concentrates, much like a lightning strike. Which is also a form of static electricity, in which about 30-50% comes out of the ground and travels to the clouds.
Another example is that your body's nervous system operates around 10,000 volts but at a very minute amperage. But 10,000 volts at just a few amps would kill you.

Luke876 · Mar 11, 2015

Unolocogringo :

Do you class an electric shock as minor static build up? I don't really understand what you are implying here - that damage to components is going to happen from touching the case and being shocked?

If you touch the case and are zapped then your components are going to be OK are they not? Why else would people recommend doing this when working on an ungrounded case?

Unolocogringo · Mar 11, 2015

Damage to the components happens when the static charge is released from your body directly to the component. The static charge travels through the component to ground.
When you touch a case the static travels around the components, not through them.
If you have flown in a plane during a thunderstorm you have flown through static electricity. Which is not damaging.
But once the static concentrates into a lightning bolt it is very dangerous.
Another example would be the coil on your car or motorcycle.
The 12v going into it from the battery is minimal but the spark4,000 to 12,000v coming out of it will cause a real jolt to your body's electrical system. .

arcitech1 · Mar 11, 2015

In the military our ESD procedures require us to connect to the equipment we are working on, not the ground line from power source, and not a separate ground point away from the unit. We are also required to secure power at the circuit breaker, not the power switch.

The goal is to have all circuit cards, cabinets and people working on them at the same 0v potential (i.e. grounded to each other) Depending on a power supply ground to protect your expensive new GPU or MB is not good practice, thick paint and rubber isolation gaskets could leave you susceptible to ESD. With modern cases, unless you have a bare metal case, you are taking a chance every time you touch it.

Also, in the US, household wiring uses the ground line as the return/neutral in the circuit. Any deranged equipment plugged into the same circuit could cause all sorts of problems. I would never remove, replace or build a computer while a power supply was plugged into the wall, never ever ever...

Luke876 · Mar 11, 2015

Unolocogringo :

But you mention in an earlier post that if an item is not grounded the electricity (ESD) will travel to 'other things' beyond the part you touched. You are implying that a component can be damaged if you touch a case, experience electric shock, and the electricity travels from the case to the component.

arcitech1 :

Even with a bare metal case you would surely still experience ESD? I have been zapped by a number of metal sinks (sinks are grounded) in the past...

Unolocogringo · Mar 11, 2015

arcitech1 :

Not sure where you are from, but where I live the Ground and Neutral circuits are different. Code requires 4 lines coming into the house. 2 hot, 1 neutral and 1 ground. Inside the breaker box all neutrals are connected to one bus bar and all grounds are connected to a different bus bar. So they are 2 completely isolated circuits.
A long time ago the ground and neutral circuits were the same, and still might be in some places and older houses. Everything built in my area in the last 15 years has the 2 as isolated circuits.

Luke876 · Mar 11, 2015

arcitech1 :

In the military our ESD procedures require us to connect to the equipment we are working on, not the ground line from power source, and not a separate ground point away from the unit. We are also required to secure power at the circuit breaker, not the power switch.

The goal is to have all circuit cards, cabinets and people working on them at the same 0v potential (i.e. grounded to each other) Depending on a power supply ground to protect your expensive new GPU or MB is not good practice, thick paint and rubber isolation gaskets could leave you susceptible to ESD. With modern cases, unless you have a bare metal case, you are taking a chance every time you touch it.

Also, in the US, household wiring uses the ground line as the return/neutral in the circuit. Any deranged equipment plugged into the same circuit could cause all sorts of problems. I would never remove, replace or build a computer while a power supply was plugged into the wall, never ever ever...

This is why you turn the switch off on the plug and the PSU.... it avoids this potential problem.

cakester5 · Jan 23, 2017

Unolocogringo :

I have always plugged the power supply in and turned it off.
On the older style without a on/off switch, I plug them into a switched bus bar and turn it off.

Either way the case is grounded and no power present inside the case.
It removes static instead of equalizing it when you touch the case, so when you reach for the next component to install you have zero static electricity.
We all have our little quirks and this is one of mine. Others may agree or disagree, but as a electrician I would rather have zero static electricity instead of equalized static electricity.

A friend of mine was severely injured while pulling new power lines. Unknown to him the ground for the spool truck was not connected.
The static build up in the line from being pulled through all of the pulleys etc... had created enough static that when he reached for the end of the line to disconnect the pull rope it entered his hand and traveled down his arm and spine and exited the rear of his leg. Taking most of his calf muscles with it.
Needless to say he is now paralyzed , from the chest down. With limited minimal use of his right arm.

Does it have to be plugged into the wall to be grounded or can i plug it into a multi outlet?

Why does plugging in a PSU to ground your PC help during a build?

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