Using anti static band - Page 1
Forum section: electronics / beginners

author: sairfan1
author_rank: Frequent Contributor
timestamp: March 02, 2019, 02:25:42 am
content: I'm not very good in electronics just work for my hobby, what i understand regarding using anti static mat, i need to clip it with some earth, but i do not have direct access to such wire, i can connect to ground wire of bench power supply, i checked with multi meter my Ground terminal is connected to earth wire of socket, please refer to attached image. I want to know does that method work?An other question comes to my mind, what if i have anti static band on my hand is it dangerous to work near by high voltage like 110vThanks

author: GeoffreyF
author_rank: Regular Contributor
timestamp: March 02, 2019, 08:22:12 pm
content: Your question probably turns on not fully understanding "Ground". Ground can be "a common point in the circuit". Ground can be "A common point to make a building electrically safe". A place in an antenna system (typically vertical) which is the counterpoise for the radiator. Ground can also mean "The earth" --- a substantial connection to the surrounding surface" (the others involve this idea as well).In your case, what you want is a place for excess charge to go. Assuming your house is adequately wired, the equipment ground or third prong of a power plug" suffices. One method I use is a power plug where the strap is ONLY connected to that equipment ground, but I verify that here is no current flowing from there to anywhere else. An other method is a cold water pipe. If I am installing a board or other component in a computer then, I touch the metal part of the computer before I bring in that part.What you mainly want is no charge to flow from your body through the device you are working on. So - if it flows before hand directly, you are all set.Here is a little experiment, assuming it's dry air where you are, shuffle your feat on the carpet and then touch something with your finger. You will feel "a shock". Now repeat with a ring and touching your ring. You will feel nothing. In both cases there is a charge transfer. "The shock" is actually the transfer creating a very small area of plasma gas which is what you feel. There isn't enough current to really shock you, though it feels that way. However, there is enough to ruin a chip either way.

author: helius
author_rank: Super Contributor
timestamp: March 02, 2019, 08:51:33 pm
content: In North America, the 120V electric outlets have a three-pin socket with Protective Earth on a circular hole about 4mm in diameter. The Live and Neutral points are rectangular holes of about 2mm in width. This means that the 4mm plug of an ESD wrist strap can be plugged directly into the outlet the only way it will fit. In other regions of the world it is absolutely not safe to do this, but in North America it is.For added convenience, some bench equipment provides terminals to plug in your wrist strap. These will either be labeled green or with a "Ground" symbol. You can plug the 4mm connector to them, or use an alligator clip adapter if the ground point is provided as a stud.

author: grizewald
author_rank: Frequent Contributor
timestamp: March 02, 2019, 10:01:14 pm
content: Quote from: sairfan1 on March 02, 2019, 02:25:42 amNo. The wrist strap should normally have a resistance of > 100K. It's normally as high as 1M. If in doubt, use your multimeter to check.

author: sairfan1
author_rank: Frequent Contributor
timestamp: March 03, 2019, 02:29:09 am
content: thanks all, looks like i got the answer, I'm in North America and we have earth wire, i just need to take care that my wrist band is properly connected with it.

author: Kasper
author_rank: Frequent Contributor
timestamp: March 03, 2019, 05:05:02 am
content: It's a little pricey at $10 but this ground plug adapter works well if you don't have an easy spot to ground your strap.https://www.digikey.ca/product-detail/en/desco/09838/16-1158-ND/3043259

author: GeoffreyF
author_rank: Regular Contributor
timestamp: March 03, 2019, 05:36:52 pm
content: Quote from: sairfan1 on March 03, 2019, 02:29:09 amConsider that the goal here is assure charges on your body and clothes do not flow into semiconductors that you are working on. If you discharge to the cabinet, ground part of that thing, then you will be fine. There is no need to be connected to the earth as far as avoiding static damage. Though rare, it's even possible that the device is at a different potential from the earth and your connection to the earth is sufficiently remote that there is a possibility of damage.For example: Working on sensitive devices, I leave it connected but turned off. It is then grounded by definition. This also applies to equipment in a car which is not connected to earth. I touch the cabinet or power supply before adding or removing circuit boards. This will protect from static discharge.You have no assurance that the equipment ground on an outlet is properly wired. TEST IT.