This One May Come As A Shock To Some

[Chris] seems to have commandeered a decent portion of the wife’s sewing room for his electronic adventures. As it is still her claim, she made it clear that his area needed some organization and a new desk. Dissatisfied with the look and feel of the replacement IKEA desk-like substance they acquired, he took it upon himself to ratchet up both the style and value by adding a copper laminate.

His decision is not purely based in aesthetic. If you’re following along, this means that his new electronics work surface is conductive. And yeah, it’s connected to ground at the wall. Although he doesn’t care for the stank of of anti-static mats or their susceptibility to fading and cracking, he does intend to use a tiny patch of it to keep his silicon happy.

[Chris] used a 20-gauge copper sheet that he cut and scored down to fit his Swedish sandwich wood base with enough margin for overhang. After scratching up one side of the copper sheet and one of the receiving base, he squidged down some adhesive nasty enough to require the rubber glove protocol and clamped it all together for several hours. Stay put the copper did, but stay flat it did not. After hammering down the overhang, [Chris] hand-burnished the copper in small swirls with a Scotch Brite pad to visually break up the slightly wavy surface. Instructional and hilarious play-by-play after the break.

84 thoughts on “This One May Come As A Shock To Some

  1. A conductive worksurface is not ESD safe – chips can easily become charged while moving them around or unpacking them, and setting them on a conductive surface will kill them as easily as zapping them with your finger.

        1. Kinda defeats the point of a conductive surface though, might as well have painted the wood to start with.

          You don’t get many germs on copper surfaces, so his wife might appreciate that.

          Maybe he can re-purpose it as a welding table.

      1. Even an amateur EE could tell you that wiring your desk to the house ground is a bad idea, because you’re creating a safety hazard by touching the desk and a faulty device.

        And the house ground isn’t ESD safe. It’s just another different potential, which can be hundreds of volts different from the actual floor you’re standing on, so he has basically just created an ESD shock-sink where setting components on the table is more likely to destroy them had he not connected it to the house ground.

  2. For what it’s worth, a good anti-static mat won’t stink or crack. I have about 8 feet of new mat, and it didn’t smell, even when it came out of the box. Another 5 foot mat I have had been in stored in a garage since the 90’s, until I purchased it. No cracking issues at all.

  3. Looks cool, but not very useful, as he wrote himself on the webpage, because it provides a low impedance path to ground, which could destroy electronics if dropped to the copper sheet. And if you are working with higher voltages, it can be even dangerous. That’s the reason antistatic wrist straps have high impedance to ground, so that you don’t electrocute yourself. But even if you add a resistor for the copper sheet, it can still short electronics lying on the sheet.

  4. This is an INCREDIBLY dangerous setup and highlighting this build borders on negligence to the community.

    Novices will want to build this thinking that it’s important to eliminate static. Novices won’t know about the dangers and are likely to die using this setup.

    The article should be removed from Hackaday.

    1. Completely agree with this assessment. Really REALLY don’t try this at home – or anywhere, for that matter. ESD mats aren’t the same thing at all, providing a high-impedance (as little as 10^8 and much as 10^12 ohms) path to ground for everything connected to it (high impedance being key to keeping the current levels of the discharge low enough to be safe to humans and electronics). Some workplaces don’t allow energized equipment on high-impedance anti-static mats (as it could energize the entire system in the case of a ground fault); this is far worse.

    2. I fully agree. HaD is negligent posting this. Please immediately delete all posts containing any of the following:

      – Working with Mains Votlage
      – Working with HV such as tesla coils
      – Working with dangerous chemicals
      – Articles containing fire
      – Articles containing projectile weapons
      – Articles containing explosions.
      – Articles showing any use of a power tool without eye and hearing protection.
      – Articles containing items small enough to be a choking hazard to children.

      While we’re at it the title of this site also has bad connotations in the media who have come to terms with the word Hacker describing North Korean attacks against media companies. In the interest of promoting a safe and socially acceptable hobby we should rename the site to Ponies and Fluffy Pillows A Day.

      And when we’re finished realise that there’s nothing at all dangerous about working on a copper matt when all you do is tinker with 5V. Not everyone is a HV / RF / other dangerous electronics nut.

    3. Agree. And it doesn’t take higher voltages to kill if you have an open cut – like cut yourself against sharp chassis corner on the old ‘scope you are refurbishing and hit the 12 volt filament supply with your other hand on the copper table top. Or the plate voltage. That will wake you up in a strange place! Consider the safety measures when wiring up equipment in a machine shop.

      If you are working on something like a constant-power supply, standard for electrophoresis, guaranteed DRT (Dead Right There).

    4. this is what comments are for – the community chiming in about possible issues both technical and safety (though people tend to go overboard). If hackaday censored posts not deemed safe we would lose much of the value and a good portion of the interesting hacks.

      No one is running to the store to do this hack which probably costs more than a ESD mat, they certainly are not doing this before reading the comments.

  5. I don’t get it. Is this a joke? Like the guy on YouTube who “accidentally” shocks himself with an ESD gun over and over again? ‘Cause that was funny the first time. I don’t know what to think of this.

  6. I believe having a layer like this UNDER an anti-static/ESD mat would be good for those doing work up to VHF/lower-UHF work. If anyone has experience with that or a similar setup please do comment.

  7. Conventional wisdom was indeed eschewed, chewed and then spat out. Please at least throw a high impedance resister between the table and ground.
    Looking at the result I am tempted to use a copper sheet on an end table along with a glass top or other sealant. It looks absolutely gorgeous!

    1. To burnish copper I would probably use a drill with a pad attached to the end, but with the copper surface there are a lot of interesting design possibilities.
      Where did he get his copper sheet from?
      If the author is still alive I hope he would consider reusing it as a coffee table.

  8. Usually people end up putting a layer of varnish to keep the surface from oxidizing…

    Question about ESD:
    Could a thin layer of natural leather be used, leather having a resistivity in the 100k range ?

    1. I don’t think this should be removed. Instead this should be considered as an example of something that shouldn’t be done. But it might be better if that was mentioned in the article and not just on comments.

      1. No. There’s a big difference between something like this that is a hidden danger to people that don’t know better, and a tesla coil project that is obviously needs to be handled with care.

        1. What is obvious to you is not obvious to everyone. What about articles talking about working with mixed voltages or vacuum tubes. What about potato canons made from PVC pipe? Did you know you can kill yourself by cleaning the toilet with two different off the shelf cleaners at the same time?

          The reality is that you shouldn’t do anything you read on the internet without a little research. And anyone who thinks its a good idea to use a copper workbench as an ESD mat is unlikely to doing anything more than playing with a 5V Arudino, which will be unlikely to kill you even if you try to stab yourself in the face with it.

          1. Don’t count on it. I had a friend whose idea of electronics experimentation was to loop a shorted out extension cord around a hammer to make an “EMP bomb”. He thought he had succeeded when the lights went out.

      2. You don’t seem to get it. There is a difference between this article and your examples. This is purely stupid and dangerous and it’s NOT stated at such. There is a difference between posting a tesla coil related article where there are probably a couple of “warning, high voltage” included, and an article that goes something like “strap a few electrodes to nipples and plug it into mains, it’s good for you! #hack”.

  9. Personally my work surface is the biggest, cheapest and flattest (least textured) tile I can get my hands on. Right now that means my soldering area is a 2″x2″ piece of ceramic floor tile. I want to say it was about a buck. Undoubtedly not the best for ESD, probably not the worst either being as I would assume it should be a fairly good insulator :D

    Do have to say that is a really nice looking work surface but I know I would personally fry so many circuits trying to work on a massive conductor :(

  10. Please don’t think you can make this safe by coating it in a non-conductive coating or placing a glass sheet over it. Doing so may remove its DC conductivity but does nothing to remove its AC conductivity.

    With an insulating coating it becomes a giant capacitor which of course is conductive to AC.

    Scenario – Switch Mode Power Supply unit with the circuit earth (largest surface area of circuit board) connected to negative of rectified mains voltage (this is common). This SMPSU then placed on coated copper surface perhaps even with a additional thin insulator. Copper then conducting AC component of rectified mains voltage. Now place your hand on the coated surface. Hand to coating to copper becomes plate to dielectric to plate of a capacitor.

    Result – electric shock or electrocution.

    Looks great but I could only rate this as safe for voltages up to 40 – 50 Volts AC MAX or 10 – 15 Volts DC MAX and current limited to 4 Amps. So that obviously means that it is not even suitable for operation of main voltage appliances ie test equipment.

    Kudo’s to [Chris] for thinking outside the box and trying something new and different however this is one of those times that in hindsight is not such a good idea. We all make mistakes and this looks like one of those.

      1. FWIW the caps in question were in a large switch mode PSU, rated at 400V, which I had just finished repairing. I’ll draw a veil over what I said at the time. Strangely discharging the caps through one of the semi’s undid the hard work I had just done repairing the darned thing in the first place. Lesson learned. Metal work surfaces and wet copper armour are best avoided when tempting fate.

    1. I think it’s great that HAD posts articles like this. It gives trolls like me the opportunity to harp on about safety and just maybe that might save someone one day.

      Some who come here are new to the industry. While experienced people might have rehearsed safety procedures to such a degree that they barely need to think about it, some newbies would benefit from pointers that they may not be aware of.

      Safety is an inherent aspect of this industry. Name any other industry where you’re working with something that travels at the speed of like, is invisible to the human eye, can move through solid substances, leap through the air and kill you instantly.

      1. “Name any other industry where you’re working with something that travels at the speed of like, is invisible to the human eye, can move through solid substances, leap through the air and kill you instantly.”

        Cool, I’m using that next parents day at my kids school. I may even put it on my business cards!

      2. I agree. The problem is- not all the youngsters read the comments of the people with experience in the particular field(s) of study involved in a project. Maybe there is a way to vote a useful (safety oriented) reply into the main body of the blog entry after a certain number of replies is reached?

        On the other hand, if a blog entry is “look at this flamethrower I built at home”, then there is probably nothing we can do to help that person learn anything about safety.

  11. This might be better listed under the Fail of the Week post. A giant highly conductive surface for electronics work. What exactly can you do with it? Obviously you can’t solder on it. It’s a giant heatsink. Next, you can’t power anything resting on it. It’s a giant path to ground. It was scuffed up for beauty. Well that’s fine, but now it will corrode and turn into a green mess. Did anyone mention breathing in burnt copper is dangerous to your health? So that rules out using it for just about anything Electronics based. It might be pretty, but it’s pretty useless. Just like a sports car with an empty gas tank.

    1. You’re at 11, dial it back a few notches.

      Can’t solder on it? I’d love to see your soldering technique.

      How’s he going to burn it? Plasma weld his PCBs instead?

      A sports car with an empty tank is useful, if you’ve got one taking up space I’ll take it off your hands.

    1. It’s nice to work on a non-conductive surface because you can cobble together something and fire it up on the bench without worrying about shorting it out.

      Also I’m not really into getting green copper oxide all over my hands and my equipment, it looks good on the Statue of Liberty but not on me.

    1. I know several ee’s who have fried instrumentation amps from static discharge

      In one case it cost $3000 and three weeks to wait for a replacement unit.

      If you live in a cold climate, get a humidifier and crank it up, that will work wonders to get rid of static problems.

  12. What people don’t realize is that, besides being a nice work surface, it is also a device to make all those annoying “colour me shocked” safety nazis go ape shit… It is hilarious..

  13. In one of the university labs at Ryerson the benches had a 6 inch wide metal band across the top, near the front edge, that was to discharge a human body static charge. The students were assembling a lab project (oscilloscope, signal generator and power supply unit). One student placed his PCB on this metal band while it was powered up. It made quite a mess of his circuit, but fortunately the TA and the tech support – both excellent troubleshooters – were able to resurrect his board. Then there was the student who mounted all of the components on the wrong side of the board..but recovered and went on to have a working unit.

  14. Some people here are not aware of the fact that all equipment with metal cases (washing machines, electric water heaters, etc) is connected directly to ground (not through resistors) precisely to trip the breaker/fuse as soon as accidental dangerous voltage connects to metal case. So his setup is actually safer in case he is working with (fused) mains voltage a lot. Resistance of direct-connect ground wire is far lower than his body resistance, so he will be mostly safe. Your high resistance pad will not trip any breaker if mains voltage is connected to it, thereby shocking you.

    1. If only it were that simple. Yes – an earthed chassis does improve safety but not in the way you have described.

      Keep in mind that when all is as it should be, there is no safety issue so you are talking about a fault condition.

      Fault conditions are not mutually exclusive so you can’t generalize about safety by giving consideration to one appliance alone as the appliance is just one component in a much more complex circuit.

      There are also unintended components to the circuit as well like metal plumbing pipes that go into the same ground that the earth potential is connected to.

      As an example that I commonly see and it’s potential danger –

      A house with an appliance (air conditioner for example) that is leaking current to earth but has no earth unbalance breakers in the fuse box. No big issue perhaps because the current is flowing back through the earth wire to the ground outside and so there is no significant voltage to be detected. No tingles or shocks or any reason for people to suspect there is a problem so it goes unnoticed and is not repaired.

      The condition of the earth wire connecting to the earth stake going into the ground is never checked and it is likely to be a poor connection but good enough to sink the current.

      Unfortunately you get a voltage drop across this poor connection that accelerates oxidation of the iron earth stake. This iron oxide then exhibits diode like properties and then you a DC component of the voltage drop. This DC component of the voltage drop will then cause electrolysis between the iron stake and the copper earth wire in humid conditions. With no sacrificial anode, the electrolysis will eat right trough the copper wire effectively disconnecting it.

      Now you have two fault conditions.

      While the ground wire is broken, all the chassis earths are still connected together by the earth link in the power box. The chassis earth of the hot water system is also connected to the metal plumbing that eventually goes into the ground and is providing a secondary path to ground so there are still no tingles or shocks or any reason for people to suspect there is a problem or attempt to have it repaired. At most someone may experience a slight tingle if that have a cut on their hand and use a tap with wet hands. People will ignore this.

      Now enter a completely unrelated fault. There is an issue with the plumbing coming into the house. A plumber has to cut our and replace a section of plumbing. They cut the first cut through the pipe removing the earth path to ground.

      Now if the air conditioner is on and they grab the live end of the plumbing then they’re dead from a combination of three faults of which the first two were never observed.

      If the air con is off and they replace a section of the metal pipe with plastic pipe then all is good for the plumber and off he goes.

      The next time the air con is on, the chassis of every earthed appliance in the house, the air con, the fridge, the washing machine, the toaster, everything is live.

      When someone touches one of these appliances they will get a shock or electrocuted. Any why? – because the plumbing was modified.

      So as you can see, you can’t assess safety based on one component in a system. The whole system has to be assessed.

      1. I think in the US the iron or steal stake is not legal. Besides it has about 1/3 the conductivity of copper. The ground stakes I have use are long (8 ft?) and 1/2 inch diameter and have a carbide tip for breaking rock. You can pound the daylights out of them with a 3 pound hammer and they don’t mushroom. Must be steel inside a copper sheath. It has to be pound till it is a certain distance below the surface. Lots of work. It is also legal to lay them in a trench of a certain depth. I recall I was required to use two of them 10 feet apart where the metered power meets the breaker panel.

        1. In Australia we have delta HV distribution systems and then Delta to Star (Wye) LV converters. Offsetting (minor) load imbalances is then done by multiple earth neutral (MEN) with earths from all end point neutral bars to ground stakes.

          The problem here is that the distribution companies responsibilities end at the domestic / commercial power box and does not include the last component of the MEN system (the earth wire / stake). This causes the power companies to be complacent about balancing phases as they can blame a part of the circuit that they’re not responsible for.

          I have had several run-ins with the electricity company about load imbalance issues on three phase sites and they get quite annoyed when you point out the them that the incoming load/phase offset must be within specification. The problem for them is that they don’t have control of the MEN earth points so the only solution for them is to install a network based MEN point which is hugely expensive for them.

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