Exploring Electrostatic Charge: Why I'm Getting Shocked in My Lab

[karthik3k]

My lab is maintaine at 20 deg. When i go near the computer screen, I am getting charged!
I can confirm this, by touching metal frames which are earthed.
I get a great shock!
Why is this so?
I never had this outside my lab.
Does the temperature have something to do with this behaviour ?

Can someone explain the physics behind this ?

 

[Gokul43201]

What kind of upholstery does the chair you sit on have ?

One thing that may definitely be a factor is the reduced humidity in the room. An air conditioner often removes water from the air (depending on the dew point of the air and the the outlet temperature of the AC), making the lab less humid than the outside. It is easier for static to build up under conditions of lower humidity (especially now in the winter, when the humidity is generally low), because water usually provides a grounding path. In labs (such as mine) where it is dangerous to have static build up, it is essential that the humidity be controlled above 40%.

 

[karthik3k]

Is there by any way i can avoid it other than by changing the humidity ?

 

[Gokul43201]

You have to pick up the charge from somewhere. It may be a woollen cushion on a seat, or something like that. If you can identify where you pick up charge, you can avoid that by some tiny modification.

Until you figure out how you are getting charged (and even afterwards, if you wish), you can periodically discharge yourself quite painlessly, if you discharge through somthing like a bunch of keys. The trick is to maximize the area of contact between your hand and the metal object that it touches (in this case, the keys) - grip the keys firmly in your hand and touch it to a metal frame. You will discharge just as before, but without the pain - since you are reducing the current density, and spreading out the current over several receptor neurons in your hand rather than concentrating it over just a few.

 

[Photongod]

Try wearing leather soled shoes instead of rubber. Photongod

 

[russ_watters]

One thing that may definitely be a factor is the reduced humidity in the room. An air conditioner often removes water from the air (depending on the dew point of the air and the the outlet temperature of the AC), making the lab less humid than the outside. It is easier for static to build up under conditions of lower humidity (especially now in the winter, when the humidity is generally low), because water usually provides a grounding path. In labs (such as mine) where it is dangerous to have static build up, it is essential that the humidity be controlled above 40%.

This would be my bet as well. Indoor humidity in the winter can be as low as 10% and has a noticeable effect on production of static electricity.

Is there by any way i can avoid it other than by changing the humidity ?

If the lab is important enough, you can request a humidifier. Static electricity is, of course, bad for electrical equipment.

 

[karthik3k]

We can't chang the humidity coz my lab works with nano bio-molecules.
I think I am getting charged by the computer monitor. or the instruments?

 

[Edgardo]

Hello karthik3k,

do you touch the screen and afterwards, if you touch a metal object,
you get a little electric shock?

Or do you touch the metal frame while having one hand at the computer
screen?

 

[karthik3k]

nope...
I din touch computer screen...
n i never touch comp n metal surface (earth) simultaneously!