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When i want to do laptop maintenance i want to ground myself with anti-static wrist strap. But how do i ground myself to laptop? Where can i find grounding point in order to not make mistake and spoil something?

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You do not want to ground yourself to the laptop. You want to be grounded to earth.

The anti-static wrist strap should have come with an attached wire. The other end of that wire should be connected to an electrical ground. The center screw of the AC wall outlet holding the cover plate is a suitable connection point that is tied to your dwelling's ground (assuming you have 3-prong outlets and the outlet is properly wired and up to code). Make sure you attach to bare metal and not the paint on the screw.

Once you are grounded, you do not want to touch any live circuit. So the equipment should be turned off and unplugged. Ideally, especially with high voltage devices, you should use the hand that has the strap to poke around and the other hand behind your back or in your pocket. The idea is that if you do get shocked, the electrical current only has a path from your hand to the strap, and not across your chest and heart.

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But i heard i can ground to laptop which is plugged in AC outlet while shut down. This is not true? –  Boris_yo Aug 11 '11 at 10:56
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No, you cannot ground to a laptop connected to an AC outlet - the laptop's power-supply is where the connection to the electrical earth stops, there is no electrical earth within the laptop chassis. You should always connect your wrist strap directly to an electrical earth and never to the equipment you are working on, regardless of whether it's a laptop, desktop etc. –  Mike Insch Aug 11 '11 at 11:23
    
@MikeInsch Thanks Mike. Just to make sure, in case I work with desktop computer, I ground to computer's chassis or power supply? I often have heard about former by the way. –  Boris_yo Aug 29 '12 at 14:36
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@Boris_yo While you can leave the AC cord connected to the power supply and then ground off to the PSU or Chassis, I personally wouldn't recommend doing so - a faulty RCD / RCBO on the supply circuit and / or a faulty Power Supply could cause current to conduct to earth via you, and while unlikely it's not worth the risk. If you must ground yourself to the equipment, you can ground to the Chassis only if the PSU is still properly mounted and electrically and mechanically connected to the Chassis, otherwise you must ground to the PSU itself. –  Mike Insch Aug 29 '12 at 14:55
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The bit about high-voltage devices really doesn't belong here. We're talking about working on a laptop, using a strap to avoid damaging it with static electricity. The kind of device where high-voltage might be present (such as a PSU) is not something the amateur should open up anyway; safety considerations aside, it's too easy to destroy the system if you don't know what you're doing. –  Isaac Rabinovitch Nov 22 '12 at 18:17
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The purpose of grounding is to allow electrons on you to flow to an object so that the voltage difference between two objects is 0. This is so you don't dissipate the voltage directly onto the motherboard and other vital components.

Mike Insch does not understand the concept of ground. A ground is merely a reference point for which other objects voltages are compared to. The electrical earth might actually have a different electrical potential from that of the chassis. This could very well be the case in laptops with only two prong power supplies

A laptop chassis can be a ground, as long as it is on a good conductor. Those plastic chassis won't work. Also, it is really difficult to find an appropriate place to clamp the wrist strap. Also, I have had many laptops power supplies only have TWO PRONGS. There is no connection to the electrical earth.

The laptop should not be worked on while plugged in or with the battery in not because of lack of earthing, but rather because there is current still flowing through the motherboard.

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Sometimes one can access fastener screws for e.g. VGA connectors. That might work as chassi ground. –  Daniel Andersson Nov 22 '12 at 18:14
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