How to ground my ESD Mat - Page 1
Forum section: electronics / beginners

author: MakkaPakka
author_rank: Newbie
timestamp: May 13, 2014, 01:12:38 am
content: Hi All, I am thinking the best way to ground my ESD Mat is to make a plug that only has a earth/ground pin on it and plug in to the 240v wall socket.Would this be ok? I can't see any problems with it my self. My local electrical shop said that most of the technicians they deal with either use a earthing stake driven in to the ground (which I have no access to) or use this method. I have also called my electrician and he also can't see anything wrong with it.Just thought I would check with you guys as well. What's the most common way to ground ESD mats?

author: Fsck
author_rank: Super Contributor
timestamp: May 13, 2014, 01:17:50 am
content: that's one way to go it, assuming your house is grounded correctly.I used the screw in the middle of the AC receptacle, which is grounded as well and saves you an outlet.

author: casinada
author_rank: Frequent Contributor
timestamp: May 13, 2014, 05:01:05 am
content: What country are you from?Find a water or gas pipe if you don't have a proper earth ground.

author: jh15
author_rank: Frequent Contributor
timestamp: May 13, 2014, 05:05:28 am
content: Gas pipe? eek!

author: rexxar
author_rank: Frequent Contributor
timestamp: May 13, 2014, 05:47:47 am
content: Quote from: jh15 on May 13, 2014, 05:05:28 amIt's perfectly safe unless you have a leak, in which case you have much bigger problems.(really it's safe even if you do have a leak. the wire is bound to the pipe, there's no gap to make a spark)

author: ejeffrey
author_rank: Super Contributor
timestamp: May 13, 2014, 06:14:48 am
content: Ground pin on the power outlet is best. That is the ground that all your equipment will be using, so you reduce small voltage offsets. It doesn't really matter for an ESD mat that is supposed to be high resistance anyway.If you have any equipment with a ground terminal on the back you can use that too. As long as the equipment is going to remain plugged in.

author: Jeroen3
author_rank: Super Contributor
timestamp: May 13, 2014, 06:54:40 am
content: The earth plug on your lab supply or oscilloscope.Or just buy/build one of these:http://www.notrax.eu/productgroup/51/2/12/ergonomic-anti-fatigue-and-safety-matting-earth-bonding-plug-1-megDon't forget the 1 M resistor.

author: Kremmen
author_rank: Super Contributor
timestamp: May 13, 2014, 07:26:33 am
content: Quote from: Jeroen3 on May 13, 2014, 06:54:40 amThat (or an equivalent product) is exactly what i am using in my ESD protection. Mine has a built-in 1M resistor for each snap connector. I have a flex snap-in wire from that to a corresponding snap in the ESD mat and from another in the next corner via a similar flex cord to the wrist strap. Simple, neat and works like a charm.

author: Kjelt
author_rank: Super Contributor
timestamp: May 13, 2014, 07:31:59 am
content: Make sure the mat attachment has a 1M ohm high voltage 1/2 or 1W resistor (or better 3 times 390k high voltage 1/2W resistors in serie) before connecting to earth.Also any wristbands and other accessories (microsscope stands, helping hand stands , solder iron etc.) need have to have their own 1M ohm resistor.

author: ConKbot
author_rank: Super Contributor
timestamp: May 13, 2014, 10:52:14 am
content: Quote from: Kjelt on May 13, 2014, 07:31:59 amESD matts are high resistance already, you dont need a resistor, the ground point on that gets earthed directly. Any metal accessories you have sitting on the mat should have their charge bled off though the matt. And your soldering iron should be grounded though the mains plug already.My preferred method is to get a metal cased power strip (double check to make sure the casing is grounded, if not return it...) and put the ring terminal for the ESD ground under a screw on the power strip. Also, you can use the center screw which holds the coverplate onto an outlet. (In the US/Canada at least, not familiar with outlets elsewhere) that is grounded, and it wont occupy a plug.

author: Kjelt
author_rank: Super Contributor
timestamp: May 13, 2014, 11:56:45 am
content: Quote from: ConKbot on May 13, 2014, 10:52:14 amI will inform our ESD specialist at the factory of your findings and ask if he will change the policyThe mat has a clipconnector which should be attached toan earth bonding plugwhich has internally always 1Mohm resistors. Check the data of your manufacturer for more information. Also the soldering irons have their own earth connectors (often banana) there you can choose if you want it hard grounded to earth or floating (not recommended) or through a 1Mohms resistor. I would always recommend 1Mohms so you can make no accidents (life circuit shorting to ground).

author: madires
author_rank: Super Contributor
timestamp: May 13, 2014, 12:07:20 pm
content: Quote from: ConKbot on May 13, 2014, 10:52:14 amThe ESD mats I know got two layers. The bottom is the conductive part and the top layer is non conductive (10G Ohms). The 1M Ohms resistors are for safety to limit the current flowing between the ESD mat and earth, but also between all other ESD stuff. Imagine that you've got something with mains voltage and somehow there's a connection with the ESD mat's conductive layer. If the wrist band woudn't have it's own 1M Ohm resistor you would have the same potential as the ESD mat, i.e. electric shock since you're closing the loop. The 1M Ohm resistor would limit the current to a non deadly value.QuoteAnother simple method is to recycle the IEC socket of some e-junk. Remove the two contacts for L and N and close the holes with epoxy or hot glue. Mount it into a plastic box, add some 4mm banana binding posts and the 1M Ohm resistors (one for each binding post). Plug in a standard IEC cable and you're done. The commercial ESD mains plugs are insanely expensive over here.

author: quarks
author_rank: Frequent Contributor
timestamp: May 13, 2014, 12:17:36 pm
content: The 1MOhm resistor is for your own safety.If you go for DIY solution, follow Kjelts suggestions and use a safety resistor.

author: ConKbot
author_rank: Super Contributor
timestamp: May 13, 2014, 01:56:38 pm
content: https://www.digikey.com/WebExport/Supplier Content/3M_19/PDF/3M_Installing_an_ESD_Workstation.pdfNo mentions of splicing in resistors or other stuff... The 'conductive' layer of the mat is quite resistive, it would be a challenge to get < 1M from the snap to any of the conductive layer with a multimeter. The grounding snap that goes from the mat to the wall is just a wire and the snap connector, and the banana sockets for the wrist strap (which has an integral 1M resistor)Feel free to add resistors wherever you want but the only resistors needed for personnel safety is the 1M in the wrist band. The mat is resistive by virtue of its own construction. If you're grounding other stuff with their own wire, to the common point, then yes, put a 1M on that also.In a home/lab environment the need to ESD every piece of equipment to the bench is on par with the need for an ionizing blower to remove surface charges on equipment. In a production environment, removal of 99% of possible ESD events isnt enough, as there are so many possible encounters. But at a home workstation, a mat, strap and all your metal equipment being on the mat will be more than enough.Also, soldering on live equipment? Naughty Naughty

author: Kjelt
author_rank: Super Contributor
timestamp: May 13, 2014, 02:18:35 pm
content: Quote from: ConKbot on May 13, 2014, 01:56:38 pmSince the connector that goes onto the mat in this case has a banana socket that does have a 1Mohm resistor are you sure the connector to the mat does not have a resistor also?QuoteAlso, soldering on live equipment? Naughty NaughtyI do not say that you should do thisyou better not do this. But humans can and will always make mistakes.

author: Kjelt
author_rank: Super Contributor
timestamp: May 13, 2014, 02:22:36 pm
content: I don't know the 3M arsenal but for instance here you got one that proofs my point: a 3M ESD mat connector with integrated 1M resistor for the mat only so indeed you should provide wriststrap bands with their own 1M resistor integrated but the mat also has one.

author: KJDS
author_rank: Super Contributor
timestamp: May 13, 2014, 02:23:23 pm
content: I've got a pile of cords and yellow UK mains plugs to connect ESD mats to earth, £8 a set (1 cord and 1 plug) including UK postage.

author: nanofrog
author_rank: Super Contributor
timestamp: May 13, 2014, 06:09:02 pm
content: Quote from: ConKbot on May 13, 2014, 01:56:38 pmYou do realize, that the cables shown in the illustration have 1M resistors built-in, don't you?For example, if you look at the data sheet for 3M's FGC151M (here), you'll see it states there's a 1M resistor (specifications section).Quote from: Kjelt on May 13, 2014, 02:18:35 pmA commercially produced cable does, just like those for wrist straps. They place a 1M resistor in the molded section for the snap connector.

author: MakkaPakka
author_rank: Newbie
timestamp: May 14, 2014, 06:45:40 am
content: Thanks for the info guys. I live in Australia so I don't have an earth screw on the power outlet. My grounding Cable has a 1M Ohm resister built in but the wrist strap doesn't. Both the wrist strap and grounding cable came as a set , so should I be looking for another wrist strap that specifically has a 1M Ohm resister built in to that as well?

author: Kjelt
author_rank: Super Contributor
timestamp: May 14, 2014, 06:47:55 am
content: Yes or buy a bonding point where the resistors are integrated and you can attach your wristband, they are not that expensive.