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Why Aren't Laptop Computers Grounded?

Wowbagger

The Infinitely Prolonged
Wowbagger
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It is the winter, and every time I have touched my laptop computer, this weekend, I got a spark. So, as a temporary measure, I started using my antistatic wristband to ground the machine. And, so far: No more sparks.

But, now the question comes up: Why don't these things have grounding plugs, to begin with?!
 
You can almost certainly order an upgraded power supply for your laptop that'll be 3 pronged. But, I have had such laptops for years now, and in the middle of winter when the air's dry enough, I still used to get shocked. Pretty damn badly too. That didn't stop until I got a humidifier for my condo. My point is that a grounded power supply for your laptop might not be a cure for the problem.
 
Truly. Humidification to reduce dryness will reduce static discharges. Where I live it gets close to desert-dry at times (esp. in Winter) and I employ a humidifier to stave off drying of my guitars (wood). This also has the benefit of reducing static electricity. Nonetheless, I'd go for that and a grounded (three-prong) plug power-supply.

And, I'll admit, that my laptop is not a 'store bought' one. It is one of those 'order to your specs' types (Nobilis). I payed more but it has nice specs - and a grounded plug. :)
 
Are you wearing the grounding strap or did you attach it to the laptop? Attaching it to the laptop doesn't make much sense. It would generally be you building up the static charge not your laptop (your laptop isn't scuffing it's shoes across the carpet is it?). And having the laptop attached to a ground wouldn't stop the spark from occurring. The static charge you build up "wants" to reach ground in order to discharge.

And laptops are designed to operate unplugged so a ground connection isn't expected to be available most of the time anyway, they have to be engineered to assume one isn't available. And it's not unusual for low voltage equipment to not require a ground connection.

And on those three pronged connections the grounding doesn't usually extend beyong the transformer anyway.
 
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kuroyume0161 said:
Truly. Humidification to reduce dryness will reduce static discharges.
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Perhaps. But, I also have a couple of desktop machines, all with grounded plugs, and they don't give me a spark.

RecoveringYuppy said:
Are you wearing the grounding strap or did you attach it to the laptop? Attaching it to the laptop doesn't make much sense. It would generally be you building up the static charge not your laptop (your laptop isn't scuffing it's shoes across the carpet is it?).
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It is attached to the laptop.

But, I think it does build up static in some of the places I put it.

Or, maybe it's got a loose wire in it.

Something to look into....
 
A loose wire won't build up a static charge. A loose wire would lead to a continuous shock except I don't think there are any voltages in a laptop computer that would shock a human.

And your reasoning is backward on the affect of grounding and static discharge. You can discharge most fully, greatest shock, in to a grounded object. If you discharge in to some isolated, ungrounded, object you have the potential for only partially discharging, lower shock.
 
Your laptop may already be grounded, but you may not!

It is not the 'grounding' that matters in drawing a spark, it is the difference in electrical potential between yourself and the laptop. A grounded device may have a greater potential difference from an ungrounded object (or person) than any two ungrounded objects have with each other. Similarly, you stand a greater chance of drawing a spark from a grounded water faucet than from the glass of water sitting on the table.

HOWEVER, if one end of your wrist strap is attached to the laptop's 'ground' and you pick up the other end before touching the laptop, you are not likely to draw a spark at all, since the potential difference will be bled off through the strap. And if both the laptop and the strap are actually 'grounded' to the water pipe (or the third-wire ground pin in an electrical outlet), you will not draw a spark from either the laptop or the faucet.

Wrist straps and third-wire ground pins act to equalize electrical potential between objects connected together.
 
RecoveringYuppy said:
A loose wire won't build up a static charge. A loose wire would lead to a continuous shock except I don't think there are any voltages in a laptop computer that would shock a human.
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Perhaps the loose wire is not continuously loose. I wonder if there is an easy way to find out.

Or, maybe some other factor is causing it to build up static.

This machine was serviced about a year and a half ago for a shorted power switch inside the monitor. And, in September, the battery had to be replaced, because its original one wasn't holding a charge.

Would any of that be relevant?

RecoveringYuppy said:
And your reasoning is backward on the affect of grounding and static discharge. You can discharge most fully, greatest shock, in to a grounded object. If you discharge in to some isolated, ungrounded, object you have the potential for only partially discharging, lower shock.
Click to expand...
Makes sense. Though, the grounding seems to help, anyway.

RecoveringYuppy said:
And laptops are designed to operate unplugged so a ground connection isn't expected to be available most of the time anyway, they have to be engineered to assume one isn't available. And it's not unusual for low voltage equipment to not require a ground connection.
Click to expand...
This, btw, at least answers the main question of the OP. (I meant to mention that, earlier.)
 
Now I have to ask the unasked question: Are you rubbing your feet on a carpet repetitively before getting on your laptop? :D

I agree with the idea that this might be related to yourself (how people spark on door handles from static electricity, for instance) or even the environment (the table, chair, floor, etc.) where you have the laptop and create electrostatic sparks.
 
Even if there is a loose wire, I don't think the voltages in a laptop are going to shock a person. And there aren't many plausible ways a laptop sitting still could build up a static charge. Are you rubbing it's plastic parts against the carpet? A cat rubbing against it? It's far more likely the charge has built up on you.

The primary reasons for grounding in the A/C grid don't exist in low powered isolated devices. The main reasons for grounding: Lightning diversion; Providing a path for high voltage to dissipate in the event of a wiring failure; Preventing the isolation transformers in the grid from building up a high voltage relative to ground. Those issues don't exist in low voltage battery operated devices.
 
The laptop is used in a variety of locations: On a wooden table (that might shift on the carpet, every now and then); on a soft ottoman-like thingy; sometimes directly on the carpet; rarely on the bed. (But I take special care not to smother the vents.)

Here's an experiment I might try:

1. "unground" the machine and have it sit someplace, untouched for a while.

2. Rub my feet on the carpet, with socks, in dry air

3. VERY IMPORTANT: Touch something that is grounded, such as a light switch, to release the static electricity. I would expect to get a spark, here. But, this is important, because of the next step:

4. THEN (after touching a ground), immediately touch the laptop. See if I still get another spark.

Theoretically, I should not get one in step 4. But, what does it mean if I do?!!

Any recommendations for locations, in step #1?

Should the computer be on or off during this experiment? Would it make a difference?

kuroyume0161 said:
Now I have to ask the unasked question: Are you rubbing your feet on a carpet repetitively before getting on your laptop?
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Not intentionally. (At least not yet.)
 
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Wowbagger said:
The laptop is used in a variety of locations: On a wooden table (that might shift on the carpet, every now and then); on a soft ottoman-like thingy; sometimes directly on the carpet; rarely on the bed. (But I take special care not to smother the vents.)

Here's an experiment I might try:

1. "unground" the machine and have it sit someplace, untouched for a while.

2. Rub my feet on the carpet, with socks, in dry air

3. VERY IMPORTANT: Touch something that is grounded, such as a light switch, to release the static electricity. I would expect to get a spark, here. But, this is important, because of the next step:

4. THEN (after touching a ground), immediately touch the laptop. See if I still get another spark.

Theoretically, I should not get one in step 4. But, what does it mean if I do?!!

Any recommendations for locations, in step #1?

Should the computer be on or off during this experiment? Would it make a difference?

Not intentionally. (At least not yet.)
Click to expand...

If the wooden table is polyurethaned, that's a pretty big ESD generator (as well as the ottoman, carpet, etc). The light switch itself isn't grounded - the screw holding the cover on may be...but the switch itself is usually plastic (for good reason - insulation). And even then, the screw head might be painted and therefore present less of a solid ground.

A "better" idea for grounding yourself in step 3 could be to insert the banana plug of your ESD wrist strap into the 3rd hole of your outlet (that's the round one people...)... Of course, I can in no way whatsoever actually advocate this. I just know that it's acceptable policy in the USAF to use the 3rd wire as a ground for ESD tabletops...
 
The laptop is grounded, if it is in good repair.

The third prong wire to the power brick grounds the brick's case, as required by electrical code for 115v AC circuits. The wires going to the computer will be two or three (perhaps more), and one of those will be double duty - it is both the common return for power and the ground. You might expect that there would be a separate ground like there was to the brick, but the voltage going from he brick to the laptop is all low voltage DC, and the code doesn't require a separate ground in that case.

The reason you got sparks in the first instance is that you grounded yourself to the computer and the static electricity drained by that path to ground. After you grounded yourself with the wrist strap, the static drained off there, and not longer when you touched the computer.
 
Wowbagger said:
4. THEN (after touching a ground), immediately touch the laptop. See if I still get another spark.

Theoretically, I should not get one in step 4. But, what does it mean if I do?!!
Click to expand...

If you do, then there is a wiring fault in your laptop, probably. If you should happen to get a tingling sensation, there is definitely something wrong.
 
kuroyume0161 said:
Now I have to ask the unasked question: Are you rubbing your feet on a carpet repetitively before getting on your laptop? :D

I agree with the idea that this might be related to yourself (how people spark on door handles from static electricity, for instance) or even the environment (the table, chair, floor, etc.) where you have the laptop and create electrostatic sparks.
Click to expand...

Speaking for myself, I wouldn't worry about a spark. You might contact the manufacturer's tech support to see what they say.

For a problem with a static-producing rug, a cheap spray bottle of anti-cling spray from the supermarket appplied to the rug will make the problem go away for a couple weeks. Reapply as necessary. I've seen this work in an office that had a killer static problem each winter.
 
Wowbagger said:
It is the winter, and every time I have touched my laptop computer, this weekend, I got a spark. So, as a temporary measure, I started using my antistatic wristband to ground the machine. And, so far: No more sparks.

But, now the question comes up: Why don't these things have grounding plugs, to begin with?!
Click to expand...

It should, but really the case should keep you from damaging the machine with a static spark.
 
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