soldering station equipotential bonding - Page 1
Forum section: electronics / general

author: metebalci
author_rank: Frequent Contributor
timestamp: February 15, 2022, 07:27:14 am
content: I wonder what people are using. I have a Weller WX1 and at the moment I use it at the default config, the tip is connected to the mains earth. I have correct/valid earth connections at my wall plugs, and I am working on ESD mat with wrist strap. Is there a benefit of bonding the tip to ESD mat common ground point ? or is there a benefit of connecting a resistor between the tip and the mains earth ?

author: Shock
author_rank: Super Contributor
timestamp: February 15, 2022, 10:19:26 am
content: Normally on an ESD safe station the iron tip is directly grounded with a minimum resistance under 2 ohms or so and if you have a dissipative mat with conductive underside that is directly grounded. Your wrist strap should have a 1meg or so resistor which clips to ground via the ESD mats ground strap or via the station, it's there to prevent a high current path to ground.If you also use a RCD type device on your mains socket or distribution panel, with the iron tip connected to ground it will trip the mains should it come into contact with a live mains reference voltage (that can pass sufficient current). These type of reasons are why unless you have a very controlled environment you do not want to float mains powered equipment with exposed metal parts.The exact standards and testing procedure are laid out in the ANSI ESD specifications.

author: metebalci
author_rank: Frequent Contributor
timestamp: February 15, 2022, 12:37:37 pm
content: Quote from: Shock on February 15, 2022, 10:19:26 amThis is exactly my setup.Quote from: Shock on February 15, 2022, 10:19:26 amYes the distribution panel has RCDs, and at the moment I have the tip connected to the mains earth, it is not floating. What I dont understand is the difference between having it connected to the mains earth through its mains connection vs. connecting it to the ESD common ground or bonding point (which in turn naturally connected to the same earth connection either before or at the distribution panel I guess). There is also another option of putting 1M etc. resistor between the tip and the earth (like the wrist strap), and actually my ESD bonding point at the wall plug also has internal resistors.

author: Shock
author_rank: Super Contributor
timestamp: February 16, 2022, 02:04:15 am
content: There are elaborate self monitoring ESD systems that plug into the mains, I've never seen them being a problem in a different socket.An ohm or so difference in grounds shouldn't be a issue, keeping in mind the mat and wrist strap are both dissipative. Ground for most intents and purposes should be the same equipotential and if you have doubts use the same socket or power strips or if the station has a ground port, connect you mat to that.In case you are thinking like - ground loops in audio causing EMI, it's not a continuously current carrying path through the strap and mat (of any significance anyway) and you would hope the stations soldering iron tip isn't a leakage current source. I assume some are though, but more likely Chinese models. Some stations won't operate properly without a ground.As ANSI ESD sets out - mains powered handtools (exposed metal) should be grounded directly. There are cases when soldering live circuits or working in places with extra special requirements, but they are not anything you would be doing at home.Some stations (certain power supplies) aren't suitable to ground lift. You would want to firstly know if it's necessary and understand the safety implications. This is why I like soldering stations with transformers and isolated but directly grounded tips, they should handle it ok.So in other words, unless you have a bad grounding system I think you are fine.I've not read up on special lab and manufacturing setups but they have full ESD safe flooring, gloves, coveralls, boots etc. They also may raise the whole environments potential above ground.The next step for a home setup would be floor mats. Unless you are manufacturing or doing live by the seat of your pants prototyping you likely will never need it. Most idiots on youtube are repairing peoples laptops with secondhand parts, no esd protection at all and leaving conductive contaminants all over the pcb. Makes me wonder how many customers had later failures.ESD the unseen killer, been using a strap since the 90s.

author: metebalci
author_rank: Frequent Contributor
timestamp: February 16, 2022, 06:25:33 am
content: OK, thanks for the detailed info

author: Kean
author_rank: Unknown
timestamp: February 16, 2022, 07:26:35 am
content: Quote from: Shock on February 16, 2022, 02:04:15 amUsername checks out