How to ground equipment in a house with no grounded receptacles?  - Page 1
Forum section: electronics / general

author: MarkS
author_rank: Unknown
timestamp: January 03, 2023, 03:19:55 pm
content: I just recently had to move in with my brother while I undergo cancer treatments. I'm setting up a workbench, but the house is very old and not grounded. The room I'm in has access to the bathroom plumbing. I'm guessing I can either run a ground tap to the cold water line or outside and drive a copper grounding stake into the ground.Which of those options would be best, or is there a better way that doesn't involve rewiring the house?

author: Siwastaja
author_rank: Super Contributor
timestamp: January 03, 2023, 03:26:32 pm
content: What are the devices you think need to be "grounded" and why do you think they need to be grounded?For ESD mitigation, you can use 1Mohm series resistor (preferably with high voltage rating, like a leaded 1kV part) to plumbing.And of course, use GFCI/RCD for safety; regardless of whether you have grounding or not. Plug-in type RCDs are cheap and do not need installation.

author: MarkS
author_rank: Unknown
timestamp: January 03, 2023, 03:29:30 pm
content: Oscilloscope, bench top power supply, antistatic pad and strap, hot air rework station, soldering station, reflow oven, etc...

author: Siwastaja
author_rank: Super Contributor
timestamp: January 03, 2023, 03:30:29 pm
content: I have used and currently use all the mentioned stuff without grounding in my previous apartment and my current house, no problem.

author: MarkS
author_rank: Unknown
timestamp: January 03, 2023, 03:31:38 pm
content: The biggest issue is the antistatic pad and strap.

author: themadhippy
author_rank: Super Contributor
timestamp: January 03, 2023, 03:31:54 pm
content: coppr stake in the ground,how can you be certain the water pipe dont turn to plastic 2" below the surface? Once youve got your stake in dont forgot to carry out a loop impedance test to verify you've actually got a good earth.

author: MarkS
author_rank: Unknown
timestamp: January 03, 2023, 03:33:06 pm
content: How do I do that test?

author: Siwastaja
author_rank: Super Contributor
timestamp: January 03, 2023, 03:42:42 pm
content: Quote from: MarkS on January 03, 2023, 03:31:38 pmStrap is useless anyway: your hands will touch / rest on the pad, so the pad alone is enough. (If your hands lift from the pad for a minute, you won't suddenly develop significant electrostatic charges.)And as you occasionally touch the pad, no electrostatic charge will form between you and the pad (both you and the pad are conductive). Grounding the pad adds additional protection by balancing the charges between the pad and the building, but OTOH even if you do that, things like non-ESD synthetic fiber mats etc.stillpose a problem.If you have electronics on the pad, and you take a break to pet your cat with synthetic cloth, when you come back, just touch the ESD mat first. Not that much difference. Me, I have plumbing (heating radiator) right next to my workspace, with some exposed metal, and Iknowit is well grounded, so I have a habit of touching it when entering the workspace (too lazy to spend the 2 minutes wiring the mat to it).TLDR, ESD mat is useful even without grounding, although grounding will make it arguably even better.Regarding piping, if you are not sure about it, don't use it for safety earthing, it can make things more dangerous.

author: SeanB
author_rank: Super Contributor
timestamp: January 06, 2023, 11:01:07 am
content: That the house is not grounded means it has not been sold (or has not been inspected) for at least a half century, as it has been kind of mandatory to ground installations for a good half century, and any sale that resulted in a bond would have required the electrical installation to comply with the minimum regulations.Best is to install GFCI outlets in your area, or combined GFCI and AFCI, and put in the ground rod, as that is, at a minimum, about the best you can hope. Unless you have an electrician come in and upgrade, which means you need to pull new cable to those outlets, with a ground wire, and connect to the main panel, where the incoming feed will have a neutral ground bond in the panel or at the meter. Old panel may be unable to do, which then means a new panel, and a total rewire, or you may find one of the old Zinsco panels that were recalled, or the breakers have also been recalled, and you are past the window for the recall to have been covered by Zinsco and 3D, as those were all in the 1980's to the late 2000's.

author: Ian.M
author_rank: Super Contributor
timestamp: January 06, 2023, 11:37:32 am
content: As Sean points out, its an <expletive> mess. *IF* the back-boxes are standard size, the outlets can be swapped out for GFCI protected ones, wired without a ground connection, and with the mandatory warning sticker that they are ungrounded, but they may not be, so you'd either have to go to surface mounted boxes, or leave the outlets as they are.Fit power strips to your bench, fed from GFCIs (either by replacing the wall outlets or inline ones), and tie the grounds of all the power strips together, and to a ground rod. Its probably best to get the ground rod installed by an electrician, as they will have the appropriate equipment to do a "fall of potential" (three rod) test to confirm its a good ground, but if you've got a Variac, an isolation transformer and two DMMs you can go 'old-skool', do the test yourself and calculate the results manually.

author: jpanhalt
author_rank: Super Contributor
timestamp: January 06, 2023, 11:41:47 am
content: Hi Marks, I have dealt with old houses in the US. How old is the house? Knob and tube wiring? Does it have a basement?Some owners opt for total rewiring, which can be more or less difficult depending on how the house was built and whether a subsequent owner has had in wall foam insulation added.As for simply grounding a single room, I have used a single, heavy gauge copper wire (e.g., 8 or 10 awg) run around the baseboard. Then, it was easy to use clamps on that wire with pigtails up to the wall sockets. That way, there were no interruptions in the safety ground. If cosmetics matter, the baseboard wire can be run behind the baseboard and the pigtails behind the plaster (?) to the outlet.As for grounding to a cold water pipe, that used to be standard practice, but fell into disfavor. I 've not checked current code, but doing that was still allowed several years ago. You need to ensure there are no breaks from the service entrance to the pipe you are attaching. Inline water meters are a potential break, but in household systems, there is usually a hefty bar between between the incoming and outgoing pipes. It is easy to check those things, if the house has a basement.Also, with the proliferation of plastic, you need to ensure the incoming supply is adequately grounded. For example, my current home was built in 1993 in a rural area far from the highway. Plastic goes all the way from the highway valve/meter to where the pipe penetrates the basement wall. That is, although the house is full of copper pipe, the incoming line is not grounded per se. My other home in the city was built in 1950, has a basement, and was easy to add grounding based on the water system that is all soldered copper.