minimum grounding rod depth for outside ESD work? - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: December 12, 2018, 04:07:50 am
content: So if you are the type of person that likes to work outside, say in a remote gazebo or something on a nice day, where you might not have power available or feel like running a cord,What would be suitable for ESD ground for a wrist strap and ESD mat?The idea being embedded systems development/programming/debugging (with portable logic analyzer). Maybe even soldering if you have a battery iron like the new milwakee one for bigger stuff, but in most cases for soldering you would run a cord.. (i like doing small drill press work outside on summer days). Though it is appealing to try to get like 200W of panels to make a outdoors solder area.

author: t1d
author_rank: Super Contributor
timestamp: December 12, 2018, 06:47:46 am
content: The solution for grounding an entire house would be a cheap and easy approach... That is, just sink a grounding rod, at the base of the structure...You will need the rod, a wire clamp and wire. Cap a length of pipe, slip the pipe over the rod and drive the rod in, by ramming the pipe down on the rod.Tie the wire to your ESD distribution system, which you can DIY as well. The ESD system should include a 1M resistor. You can search for these circuits.https://www.lowes.com/pd/Galvan-0-625-in-x-8-ft-Copper-Grounding-Rods/3446270

author: coppercone2
author_rank: Super Contributor
timestamp: December 12, 2018, 07:04:41 am
content: no you misunderstood I mean minimum length that will work for ESD protection without having to beat a 8 foot rod or carry 8 foot rod with you.I believe a army munitions disposal video had the answer I am looking for now that I thought about it hard (for grounding the shells in a field location during disassembly).

author: BravoV
author_rank: Super Contributor
timestamp: December 12, 2018, 07:25:03 am
content: I thought basic law of electronics still applicable, it depends on the soil's conductivity isn't it ? A wet swamp definitely differs much compared to say dry desert soil.Measurement tool like megger (earth & resistance meter) supposed to tell you how deep is "enough".cmiiw

author: coppercone2
author_rank: Super Contributor
timestamp: December 12, 2018, 07:39:33 am
content: no it is I just never thought home grounding is an issue since you connect with a 1 meg resistor anyway, so it might be overkill

author: babysitter
author_rank: Frequent Contributor
timestamp: December 12, 2018, 11:47:56 am
content: You want equivalent potential on yourself, the parts and all surfaces they touch, so, just local, right? No need for proper grounding if you control all available surfaces.

author: ogden
author_rank: Super Contributor
timestamp: December 12, 2018, 11:58:37 am
content: Electronics workstation in a middle of the field? Wow...In case it is not desert but field covered in grass then even 1 feet metallic rod into ground is enough. If unsure - pour bucket of water onto it

author: coppercone2
author_rank: Super Contributor
timestamp: December 12, 2018, 04:00:15 pm
content: Quote from: ogden on December 12, 2018, 11:58:37 amconsidering the insane stress levels you can get from debugging something or doing alot of repeditive soldering work (not as bad) (like mounting LED or sensors or something to cables), i think its a good idea, also you don't feel like you wasted a good summers day.Something like PCB assembly requires better power at this point and wind might be a problem etc.

author: jmelson
author_rank: Super Contributor
timestamp: December 12, 2018, 08:08:02 pm
content: Quote from: coppercone2 on December 12, 2018, 07:04:41 amForget the ground rod. Spread a static-dissipative work pad on your bench, ground yourself to it with wrist strap. Then, open all packages of parts on the pad, and do your work there, without getting up. If you have to get up to go get something, disconnect the wrist strap last and reconnect it first, before touching anything.This will work fine unless humidity is insanely low.I work without ANY ESD protective gear except for the packages the parts come in. We do have a humidifier in the house in the winter. I've rarely had any problem doing this in the last 40 years. I do watch out for static-producing clothing and ground myself to the metal bench before touching anything. This is all nearly unconscious behavior by now.Jon

author: coppercone2
author_rank: Super Contributor
timestamp: December 12, 2018, 08:25:34 pm
content: thats good to know. I can't find the video now but I am pretty sure the US military in around 1950 decided that you should use a 2or 3 foot grounding rod for doing a field ground for a munitions inspection, retrofit and disposal operation under field conditions. Basically they just had the powder boxes grounded (where you empty the propellant from the shell).This is the video but I rewatched the part where I thought they mention it, and they just said it should be grounded without telling you how to ground it, maybe its in a diff video or another video or in another part, I might watch the whole thing again if I am bored but I am pretty sure the military said 2-3 feet some where.I doubt a 2 foot rod will hurt anything right? It's reasonable enough to carry and feels proper. But I think I understand what you are saying since the body resistance is like what 150k, the resistor in the strap is 1 meg and the mat has a high resistance too, so it should become equipotential quickly.Is you assertion still true if you have one of the blue/black mats, where the top is very high Z and the bottom is more conductive? The heavy duty rubber ones that are very tough and expensive.

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 12, 2018, 08:45:19 pm
content: You don't need earth grounding, equipotentiality should be all that matters. So a possible solution would be to carry two conductive (ESD) mats, one smaller for your desk/table and one larger you'd put on the ground under the table and yourself if you really want to get it right. Connect them together and yourself with a wrist strap, that should be ok?

author: coppercone2
author_rank: Super Contributor
timestamp: December 12, 2018, 08:52:14 pm
content: all I can think of is that the mat can charge up like a capacitor if its not drained and build up to some ridiculous charge and then the equalization could lead to a current pulse ? I assume by grounding it and removing the parts from a static bag you are keeping the differential to like what, 500V?Like a helicopter near the power lines with a floating shielded guy still sparks because of the capacitance IIRC.But in this situation I am imagining myself sitting on the matt and working on the mat as the power line and the part as the helicopter?

author: Gyro
author_rank: Super Contributor
timestamp: December 12, 2018, 09:41:59 pm
content: Mats are conductive all the way through - in fact the normal black underside isconsiderablymore conductive. One of those (floor mat) is all the ground contact you're ever going to need.

author: coppercone2
author_rank: Super Contributor
timestamp: December 12, 2018, 10:47:09 pm
content: I guess the top layer is thin so its misleading to do a point to point measurement on the top