How do you -really- ground yourself?

February 28, 2008 9:11 PM

Help me clear up my understanding of how to ground myself when working on my computer.

I generally thought that as long as I touch something metal that can conduct a charge to the earth without being interrupted by say, my rubber shoe soles, then I was 'grounding myself'. And I figured that even if I am not in constant contact with said metal object, as long as I wasn't shuffling around on the carpet in my socks I wouldn't build up a sufficient static charge if I hadn't touched the metal object in a couple of minutes. Now I fear I may be completely off base what with talk of static discharge wrist bands that you attach to your ground plug in your electricity socket, and talk of leaving the computer plugged in to ensure that the ground is being reached through the ground plug...
I generally work on my computer on the carpet but I figure it doesnt matter because usually i will put a metal object under my foot. How does one ground oneself?

posted by GleepGlop to computers & internet (14 comments total)

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posted by neuron at 9:13 PM on February 28, 2008

generally thought that as long as I touch something metal that can conduct a charge to the earth without being interrupted by say, my rubber shoe soles, then I was 'grounding myself'. And I figured that even if I am not in constant contact with said metal object, as long as I wasn't shuffling around on the carpet in my socks I wouldn't build up a sufficient static charge if I hadn't touched the metal object in a couple of minutes.

That's all basically true. But wearing a ground strap removes all anxiety and pretty much all risk, so it's a good idea if you're working on something expensive.

The critical factor is that your charge level be the same as the circuit you're working on. So you wear a ground strap, and you clip it to the metal case of the computer. You don't have to connect to the earth ground in a power outlet -- which is a good thing, because probing around inside of electrical outlets isn't really very smart.

Putting a metal object under your foot is pretty useless. Just because it's metal doesn't mean it's ground; it just means it's a good conductor. If it's sitting on the carpet, then it probably isn't very well grounded, and it can hold a charge just like you do when you're standing on the carpet. Touching it may drain some charge off of you, but won't necessarily drain it all.
posted by Class Goat at 9:21 PM on February 28, 2008

Well, when I work on computers, I don't usually work on them in a carpeted room. What I DO do, however, is unplug the power supply from the motherboard, and turn the power supply switch off at the rear of the power supply, but leave it plugged in to the wall with its grounded outlet. Then, before I touch anything important I touch the exterior of the power supply with a finger, which grounds me. Then I go ahead and work away, invariably in the course of whatever I am doing I end up touching flesh to the case every few seconds, which is of course connected to the power supply, which is grounded. Thus, constant grounding happens easily, and I don't fry components.

I tried the grounding straps but found them annoying. I like my method better, and the last time I fried a component with static electricity was in the early 90's, so it works for me. *shrug*
posted by barc0001 at 9:27 PM on February 28, 2008

Do NOT leave the computer plugged in while working on it!

All the advice here is spot on. The important thing about voltage is that it's relative, not absolute: it's the difference that matters. You could sit on a high-voltage transmission line and be totally safe. But if you touched the ground with one foot while sitting on it, things would get exciting because now there's a voltage difference between your extremities.

I don't like static straps. What I do: before touching anything critical, touch the metal chassis (power supply case, or the frame that holds the motherboard) with all my fingers, palms etc.. Also touch all tools, components, etc. to the chassis. Now everything's at the same voltage and it's safe to start. While working try not to brush against plastic, cloth etc. (especially cats!) that might cause a charge buildup.

And don't forget, unplug that computer before working on it.
posted by phliar at 9:59 PM on February 28, 2008

barc0001 is correct. It's common practice and fairly safe unless there is something seriously wrong with the power supply. If the PS is good and the wire is ok and the plug is properly grounded, it will work just fine for regular computer stuff.
posted by MasterShake at 10:33 PM on February 28, 2008

I've heard that all you have to do is touch the back of your computer. Is there any truth to this?
posted by Afroblanco at 10:34 PM on February 28, 2008

You don't need to be grounded or earthed, what you need is for yourself, the computer, anything you are adding to the computer, and any surface on which you are placing circuitry from the computer, to all be at the same potential (which is another way to talk about voltage). Grounding everything is one way to do this. Regular touching will do this. If you are in a factory or other area where a lot of surfaces and components will be coming into contact in lots of ways, then grounding everything ensures everything stays at the same potential (ie ground). If you have one work surface, one computer and some components, it's not going to matter what the potential is (relative to ground), so long as you don't accidentally introduce something with a different charge into the mix.

So yes, just be in frequent contact with the case, and don't be generating any further charge by nervous scuffing/rubbing :-)

Likewise, if you are swapping cards, be in contact with any surface where you will put down the card, while holding the card, before letting the card touch the surface. (If you are wearing a wrist strap, you should still do this is the surface is not connected to the strap - if the card is earthed and the surface charged, that's still a difference in potential).

For extra brownie points, have the point of first contact between card and surface be something that is not part of the circuitry, so if there is a static discharge, it's not discharging directly through some IC pin.
posted by -harlequin- at 11:08 PM on February 28, 2008

High end routers have a hole in the front to plug in a wrist band. Almost every replacement part comes with an el'cheapo wrist band. I have one in my bag and one in my desk. Your PC, yeah who cares... replacing a $50,000 router board... wear the static thingy.

Old ungrounded ethernet cables between buildings could give you a 'f*ck' I'm dead jolt from ground potential differences between buildings.

It's a 90% you'll be fine, and the rest... you're maybe dead or you've just fried a $50,000 piece of equipment.

But yeah, for PC... leave plugged in, touch metal ground, don't move around much... (naked PC repair anybody...).
posted by zengargoyle at 12:27 AM on February 29, 2008

Don't worry about frying your system when touching the case, either. Your electronics should be shielded by the case itself, so touching the case (even if you get a bit of a shock) should not damage the electronics. Touching the electronics first? Bad.

As an example a few days back I was wearing a lab coat at work, and EVERY time I took it off to sit down at my laptop I got zapped when touching the aluminum case. Laptop was fine, because the case itself isn't in direct electrical contact with the interior components (if it were, touching the case would subject you to live current, which is bad!)
posted by caution live frogs at 6:39 AM on February 29, 2008

Another data point- I too have heard that you should leave the PC plugged in, but switched off, when servicing it. I guess the reason is that when unplugged, you and the PC could conceivably build up a static charge. You won't kill it while you are working on it because you and it will have the same charge. What will happen is that when you plug it back in it will ground itself and that will zap it.

Similarly, I've heard that while using a grounding strap might be beneficial to the electronics, it is actually less safe for you if you were accidentally to touch a live circuit. You've just made yourself part of a circuit.
posted by gjc at 7:03 AM on February 29, 2008

I agree with barc0001 wrt the ground from the power plug. Although I don't unplug the power supply from anything.

I agree with -harlequin- re everything just needs to be at the same potential, and first point of contact best practices.

Like zengargoyle, if I'm swapping out 96 DIMMS, sitting on the floor of the data center, I'll often wear the enclosed disposable wrist strap, just 'cuz, hey, that RAM's worth more than my car.

The service technicians sent out by computer companies all wear wrist straps that are connected to ground. Some bring their own work surface, upon which all replacement parts are to rest, and that work surface (think of a vinyl blanket) is itself grounded.

BTW, stepping on something metal will not dissipate charge, unless that metal is grounded. It could actually increase your charge.

I've been working on very expensive computers (worth tens or hundreds or even thousands of thousands of dollars) for over a decade. I've broken my share of computer parts by bending a pin, or putting the part in the wrong way, or not using the right tools to pop chips off of the mobo, or mis-torquing a CPU or daughter board, or dropping the shaft of a screwdriver into the card cage, or shutting the fibre in a cabinet door by accident, or letting it fall off the handtruck, etc, but so far I haven't zapped anything. Yet.
posted by popechunk at 7:07 AM on February 29, 2008

"I've heard that while using a grounding strap might be beneficial to the electronics, it is actually less safe for you if you were accidentally to touch a live circuit."

This is not true, a proper grounding strap has a very high impedance. Too high to allow a dangerous current to pass through.

"...but so far I haven't zapped anything."

I don't think you have a basis to make that statement, popechunk. Sometimes ESD damage is obvious, but most times it is not. The failure can occur weeks or months after the ESD event.

When I work on *my* computer, I always wear a grounding strap connected to the chassis. And any components not in the machine are always in a static bag.
posted by kc8nod at 9:38 AM on February 29, 2008

If you work on computers often I would recommend buying a space humidifier that is capable of elevating the work room's humidity to about 40-60% RH. It is very difficult to generate static at elevated humidity levels and static is the reason why you "ground" yourself. I would say a humidifier is probably a better option. Also, not working on carpet helps as well.
posted by nickerbocker at 3:33 PM on February 29, 2008

Thanks, I learned something!
posted by GleepGlop at 10:42 AM on March 1, 2008