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How do you really ground yourself?


vipejc

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I can't find a straight answer. There's two camps. One camp says just touching a bare metal object grounds you (I'm a member of this camp), and the other camp says the bare metal object must be connected to the ground (Earth). Who is right? All the OEMs agree with my camp, saying to ground yourself, all you have to do is touch a bare metal object, like the computer case or a card connector. I don't think OEMs would give misinformation and cost themselves their reputations and finances, but who do you think is right? In all my nine years in this business, I've never damaged hardware by ESD, and I always use an anti-static strap attached to the bare metal case frame when working inside my box, so obviously grounding youself does NOT require the bare metal object to be connected to the Earth, because the case is on a table. So really, you could simply hold a bare metal key in your hand and stay grounded the entire process, right?

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In all my nine years in this business, I've never damaged hardware by ESD...

That you can't tell, damaging could result in shorter life as well, and it is hard to tell if it was you or fabrication.

When I build a system, and I've build quite a few I must say, I just touch the bare metal from the case (housing) and that should be enough to work secure, but just a small metal object won't do (like a key), it needs some volume.

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In all my nine years in this business, I've never damaged hardware by ESD...

That you can't tell, damaging could result in shorter life as well, and it is hard to tell if it was you or fabrication.

When I build a system, and I've build quite a few I must say, I just touch the bare metal from the case (housing) and that should be enough to work secure, but just a small metal object won't do (like a key), it needs some volume.

Sure you can tell if you damaged hardware by ESD. If you own a hard disk for 16 years, you know ESD didn't harm it. When you say the bare metal object needs "volume," do you mean it needs to be at least as big as the computer case? If so, why does the size of the object matter? Isn't bare metal, bare metal?

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What you really need to worry about is voltage potential between you and the sensitive hardware. All electrical components in the case should have a common ground, except for perhaps the hard drives if they have some sort of anti-vibration mechanism and are disconnected from the power supply. This is the reason grounding straps are meant to be connected to the computer chassis.

Avoid working on wool carpeting, or near anything else which may create large amounts of static electricity such as old CRT monitors or televisions.

Edited by 5eraph
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But let's say you're working on a motherboard out of the case and on a work bench. Would holding a bare metal key or tweezers ground you and protect the motherboard from ESD? I just want to ensure I really am grounded when I can't use my strap because no large bare metal objects are around.

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But let's say you're working on a motherboard out of the case and on a work bench. Would holding a bare metal key or tweezers ground you and protect the motherboard from ESD?

The key term is "common ground". If you must work on components without a chassis then ground the component and yourself to a common object, such as a metal table. The screw holes of the motherboard are ground connection points.

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But let's say you're working on a motherboard out of the case and on a work bench. Would holding a bare metal key or tweezers ground you and protect the motherboard from ESD?

The key term is "common ground". If you must work on components without a chassis then ground the component and yourself to a common object, such as a metal table. The screw holes of the motherboard are ground connection points.

You're right. I didn't think of it. So if I touch the motherboard screw hole, am I grounded and the main board protected?

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It depends also on your environment.

If you are wearing wool or nylon/polyester clothes and sneakers, and the room you work in has a carpet, it is possible that you charge yourself with a zillion volts. :ph34r:

If you are bare-footed, wear cotton clothes and the room has a concrete pavement, you are simply inherently grounded.

BUT having an equipotential connection to the device ground is good anyway, as long as the device is also grounded.

jaclaz

Edited by jaclaz
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When you say the bare metal object needs "volume," do you mean it needs to be at least as big as the computer case? If so, why does the size of the object matter? Isn't bare metal, bare metal?

I can't speak for him, but my "layman's" explanation would be that the size of metal object needs to be large enough to receive/absorb the electrons that have been built up (or lack of them, but ignore this because the result is the same). So maybe smaller than a case, but definitely larger then a key - in "normal", everyday conditions one might encounter.

GL

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When you say the bare metal object needs "volume," do you mean it needs to be at least as big as the computer case? If so, why does the size of the object matter? Isn't bare metal, bare metal?

I can't speak for him, but my "layman's" explanation would be that the size of metal object needs to be large enough to receive/absorb the electrons that have been built up (or lack of them, but ignore this because the result is the same). So maybe smaller than a case, but definitely larger then a key - in "normal", everyday conditions one might encounter.

GL

It sounds right. And I think I can simplify the subject. All you have to do to ground yourself and protect hardware from ESD is keep you and the hardware grounded (connected) to the same bare metal object. For example, wear an anti-static strap and attach it to a bare metal part of the case. If you can't do that, because, say, you're working on a motherboard, then touch a bare metal object off and on, like a door knob, until you're done working on the hardware. The object does not have to be touching the floor (Earth or grounded) to properly ground yourself. I can't find an answer that proves the size of the object must be at least as big as the case, though.

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If you can't ground yourself and the component (like a motherboard) to the same object, then larger grounds are better. It's surface area that matters, though, not volume since electrons travel and collect mostly on the surface of a conductor. The larger the surface area, the greater the ability of the grounding surface to dissipate electrical charge.

Edited by 5eraph
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If you can't ground yourself and the component (like a motherboard) to the same object, then larger grounds are better. It's surface area that matters, though, not volume since electrons travel and collect mostly on the surface of a conductor. The larger the surface area, the greater the ability of the grounding surface to dissipate electrical charge.

Now I understand. Thank you for that scientific explanation. But holding a metal key in your hand is better than nothing, right? Yes, it's not the most effective grounding method, but is it at all effective, even if just a bit? I mean, it is metal.

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For the record the object that is LEAST grounded in the mentioned example is a door knob (on a wooden door), and I doubt it has enough mass to be of any good, maybe very old type solid brass ones may do, but common cheap aluminium ones won't.

What we did (many, many, many) years ago was to charge with high voltage static electricity door knobs in school and wait for the first one that would attempt opening the door.

If I recall corrrectly it took more than 10 seconds before the door knob lost it's electrical charge.

@vipejc

No, it has definitely not enough mass and it is NOT grounded.

jaclaz

Edited by jaclaz
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