Where can I buy North America version of grounding plug?

[eeguy]

Hi,

I want to ground myself before using electronics components. I have an anti-static wrist strip already but no source for grounding. I am looking for something like this item to be used in Canada. Any suggestion on where to buy it?
 
https://shop.paperchain.net/anti-static--noshock-esd-grounding-plug---various-connections---1-x-10mm-stud-and-2-x-4mm-socket--uk/pi/PCV50064--49835-1.html

[timelessbeing]

Can't you just cut off a power cord?

[Ian.M]

Take a rewirable NEMA 6-15p plug,  insulate the Line and Neutral terminals inside it so the ground wire cant contact them if it comes loose, and connect the ground to a small box containing 2x full size 1/4W 560K resistor in series (for your safety) between the incoming ground, and a couple of 10mm press-studs (available from any good marine chandler or canvas-work shop), 4mm sockets, or whatever other  connector your ESD grounding accessories use.  You could also skip the NEMA 6-15p plug and instead, fit a IEC C14 inlet on the small box (L and N insulated as before) and simply plug it in with an ordinary PC power cord.

Its also worth fitting a 'hard ground' screw terminal post that can take 4mm plugs, connected direct to the ground wire for occasions when you need to ground equipment chassis etc.  *NEVER* use a 'hard ground' for personal grounding as it increases the risk if you get a shock.

[eeguy]

I touched the computer case a few times and got some kind of electric shocks. Do I have to worry? Somebody mentioned that I should plug the power cord from the power supply to the electric outlet, have the power supply of the computer off, connect the anti static wrist strip to the unpainted metal frame of the computer case before installing/uninstalling the components. However, my case came fully painted. I think the power supply is the same. So it means even I connect the wrist strip clip to the case, I don't get grounded. What suggestion do you have?

[Gregg]

I have an older model (made in USA) outlet strip that the metal case is screwed together.  I simply put a green binding post near one end and connected it to the ground wire.  Older outlet strips are often available in thrift stores and yard sales for next to nothing.
Also the standard North American three prong 120 volt plug is a NEMA 5-15P. 

[eeguy]

Is it dangerous to touch the "supposed" to be ground on the wall outlet? Will I get killed sticking a metal in that hole? I am living in a condo in Canada. Don't know if those previous owners have done anything to the wall outlets. The former one surely fooled around with various things in the unit before I moved in.

[GreyWoolfe]

I took a cheap 3 prong replacement plug from Home Depot and removed the line and neutral terminals.  I attached the ground point wire to the ground pin using a banana plug and jack and plugged into an unused outlet.  Maybe that would work for you.  I have a 2 outlet ground point that snaps onto the 10 mm stud on my ESD mat.

[timelessbeing]

I touched the computer case a few times and got some kind of electric shocks. Do I have to worry?

You should be worried that your body is generating a lot of static electricity. You want it to jump to the case, but if it happens so frequently then you definitely want to wear the strap.

However, my case came fully painted.

I've never seen a case that is painted on the inside. Even if it is, there must be some unpainted screws.

Is it dangerous to touch the "supposed" to be ground on the wall outlet?

No it's safe. Otherwise everything in your house would be live.

[Ian.M]

Is it dangerous to touch the "supposed" to be ground on the wall outlet?

No it's safe. Otherwise everything in your house would be live.

That's only true if the outlet in question is properly wired and grounded.  If its on a GFCI protected circuit, the chance of it being dangerous is vanishingly small, but if you are in an older property without whole-house GFCI protection, and there is a break in the ground between the outlet and the panel feeding it, the combined ground  leakage current of all other devices on the circuit may add up to enough to be dangerous if you become part of the ground path. e.g. by touching the outlet ground with your other hand on a water pipe. 

If in doubt, check the ground integrity.  A socket tester will tell you its probably grounded OK, but if you want to be absolutely certain you need to check the ground resistance is within the limits set by the NEC, using a sufficiently high test current to fuse any weak connections that would be likely to fail under fault conditions.  That's a specialised test, best left to a professional electrician, who will have the appropriate test equipment.

[timelessbeing]

the combined ground  leakage current of all other devices on the circuit may add up to enough to be dangerous

What are the chances of this? Wouldn't that require some spectacular failure?

[james_s]

Touching the ground terminal in the outlet is the same as touching the metal housing of any grounded appliance plugged into the outlet. If there is any doubt you should test your outlet to make sure it's wired correctly and properly grounded. This is true whether you want to ground a wrist strap to it or just plug something into it.

[Ian.M]

the combined ground  leakage current of all other devices on the circuit may add up to enough to be dangerous

What are the chances of this? Wouldn't that require some spectacular failure?

The chance is pretty small, but no actual fault (other than the upstream open ground) is required.  All it needs is a *LOT* of PCs or similar equipment with grounded SMPSUs on the circuit.  However if there is a second fault and no GFCI, then everything 'grounded' on the circuit may already be live, with no one realising until some unlucky sod gets electrocuted.

If the O.P. is getting shocks off the PC chassis, and its plugged into a supposedly grounded outlet, the question that must be asked is: Do you ever get a second shock if you touch it again without otherwise moving around?  If the answer is yes, it may not be ESD, so isolate the circuit at the breaker and call in a professional electrician.

[TheNewLab]

Just cutting off a 3 wire grounded plug, using a resistor on the ground wire is the simplest. In my case, I just cut into the ground wire of a computer cord. 500K resistor extended to a 1M connector box for straps and anything else needing connection.
I went ahead and kept the rest of the cord running it to a 2 wire polarized connector I had and spliced into the computer cord. So long as the ground wire is safely isolated, with a resistor to protect yourself you are fine.

most straps have 1M resistors, but you still want a small resistor at the point of splicing into the ground (as stated above)..just to be safe.

[timelessbeing]

All it needs is a *LOT* of PCs or similar equipment with grounded SMPSUs on the circuit.

How many?

if there is a second fault and no GFCI, then everything 'grounded' on the circuit may already be live, with no one realising until some unlucky sod gets electrocuted.

Right, so if there's a fault AND if there's no gfci AND if the ground circuit isn't actually grounded...

If it were a problem, then you couldn't have anything with exposed grounded chassis (microwave, stove, PC etc...). Essentially, we can call it "safe". And it should be, because it is exists preceisely to protect you from faults.

[Ian.M]

The max leakage current permitted for grounded IT equipment is 3.5mA.  A single workstation consisting of a PC, monitor and printer, could therefore leak over 10mA to ground, enough for a significant shock.   A home office with a couple of PCs, or a PC and a multimedia center will probably leak over 10mA to ground. 

To get lethal levels of leakage current, you more or less have to have an appliance suffering from partial insulation breakdown.  Heating, cooking, refrigeration and washing appliances are particularly liable to faults of this nature.  Without GFCI protection, such faults typically go undetected so long as the ground connection remains intact, until the insulation 'cooks' enough to fully breakdown and blow the fuse or trip the breaker.  Therefore on a non-GFCI-protected circuit, a open ground fault can immediately present a lethal hazard.

If you value your and your family's lives, fit GFCI protection on *every* circuit feeding socket outlets!

[timelessbeing]

A single workstation consisting of a PC, monitor and printer, could therefore leak over 10mA to ground, enough for a significant shock. 

Sorry but this doesn't make any sense.
I have several such devices (more than you describe) connected in my office, and they certainly do not give me "significant shocks". There would have to be close to 100V just to penetrate your skin (in addition to an open ground circuit).

If you value your and your family's lives, fit GFCI protection on *every* circuit feeding socket outlets!

In North America this simply isn't common practice, and families aren't dying.

Your claim that touching household ground is dangerous, is nonsense.

[Ian.M]

You cant get a shock from the ground leakage current of grounded equipment  if the ground conductor is intact all the way back to the panel and the grounding rod.  3.5mA is the worst case limit (in most 230V countries), and with a 120V supply + equipment having less than the permitted leakage current its probably <1mA per item.   If it was more, nuisance tripping would be an even worse problem than it is due to your NEC calling for class A GFCIs for personnel protection with trip current in the range 4 to 6 mA.  That's fine for a single or duplex outlet but risks nuisance tripping if you feed more outlets off it.   

IMHO that's self-defeating on the part of the NEC as it discourages the use of GFCI protection on circuits that don't require it by code due to the expense of fitting individual GFCi outlets to avoid the nuisance tripping problem.

The rest of the world typically use GFCIs in the 10 to 30 mA range, often combined with an over-current circuit breaker, to feed a whole circuit, and in developed countries, there is an increasing trend to protect *ALL* domestic circuits.  There's a slightly higher shock risk due to the higher trip current, but that's mitigated by the much higher probability that an outlet will be GFCI protected.

[eeguy]

the combined ground  leakage current of all other devices on the circuit may add up to enough to be dangerous

What are the chances of this? Wouldn't that require some spectacular failure?

The chance is pretty small, but no actual fault (other than the upstream open ground) is required.  All it needs is a *LOT* of PCs or similar equipment with grounded SMPSUs on the circuit.  However if there is a second fault and no GFCI, then everything 'grounded' on the circuit may already be live, with no one realising until some unlucky sod gets electrocuted.

If the O.P. is getting shocks off the PC chassis, and its plugged into a supposedly grounded outlet, the question that must be asked is: Do you ever get a second shock if you touch it again without otherwise moving around?  If the answer is yes, it may not be ESD, so isolate the circuit at the breaker and call in a professional electrician.

I touched the case about 10 times (don't remember if the computer was on or not). Half of the time I got such shocks. I also got shock one time I touched the heatsink when the machine was on. I asked the case manufacturer a week ago. They are still investigating the course but no definite answer yet. So, I suspect may be the outlet is not properly grounded or there is something wrong with the power supply. I asked the power supply company Corsair but they have no comment.

Case manufacturer told me that there is no unpainted metal part of the case.

My area is about -15c to -30c this week. The shocks happened when  the temp was about 5 to -10c.

[Richard Crowley]

https://www.amazon.com/StaticTek-Adapter-Universal-Connection-Unbreakable/dp/B071J61CSV

[Ian.M]

Start by unplugging the PC from the wall and checking continuity from a screw on the PC PSU to the ground pin of the plug on its power lead.  If its got continuity, the next step is to go to the hardware store to get an outlet tester, and check the outlet.  If it doesn't pass (see tester instructions) go round your house testing all the three pin outlets, mark those that fail, then you need to consult an electrician.   

The electricity supply company's responsibility ends at the meter - if they are delivering power that meets the standards that far, anything past that point is the responsibility of the homeowner, so don't expect much from the supply company s helpline other than "Call a licenced electrician"

[eeguy]

Thanks Richard and Ian for the suggestions. Just performed continunity tests by connecting one probe of the tester to the ground pin of the power cord of the PSU and the other probe to the point of test. Here is the results:

1. Beep sounded when the other probe touched any of the screws that connect the power supply to the case. Does that mean if I connect one end of the wrist strip to one of the screws, I will be grounded?

2. No beep sound when the other probe touched the screws that connect the motherboard to the computer case. (How they ground the motherboard then? Via wires that connect usb ports from the case to the motherboard?)

3. No beep sound when the other probe touched the surface of the computer case.

4. No beep sound when the other probe touched the surface of the PSU.


In this case, for convenience, is it still better to buy one or two StaticTek adapter(s)? Besides building computer, I will build some electronic circuits at home as well.

My electric outlet is like the one shown in the StaticTek product page. Before I did the tests, I was thinking of:

1. Buy one StaticTek Adapter and connect it to the wrist strap
https://www.startech.com/ca/Computer-Parts/System-Build/Anti-Static/Anti-Static-Wrist-Strap~SWS100

2. Buy another StaticTek Adapter and connect it to the matt
https://www.startech.com/ca/Computer-Parts/System-Build/Anti-Static/24x27in-Beige-Desktop-Anti-Static-Mat~M3013

Can I assume for sure that those two 3-pin sockets are connected to the same ground? If they are not, I may introduce a potential different in grounds which is not good.

[Ian.M]

The tray the motherboard is mounted on should be grounded, and motherboard screw holes that have a silver coloured ground pad round them should be screwed down to a metal standoff pillar so those screws should be grounded.  However paint is an insulator so it is likely your PSU doesn't ground properly to the case.    Fortunately the 0V wiring coming from the PSU and going to the motherboard and drives is normally internally grounded in the PSU and that will be grounding your motherboard.  Check continuity between the PSU screw you tested to earlier, and a black wire on a spare drive power connector (old style connector not SATA power connector) to confirm that.

Fixing your PC's internal chassis grounding problems could be quite tedious.  It will probably involve a lot of work scraping away tiny circles of paint under screw heads, and/or fitting serrated washers under the screw heads.

I wouldn't trust there not to be a potential difference between two outlet grounds unless they are on the same faceplate or power strip.  However ESD grounding almost invariably has high value series resistors, and potential differences in grounding systems are typically very small, so with no low impedance path between the two grounding plugs other than the ground wiring in the wall, there are no significant risks to you or to equipment.   Before putting multiple grounding plugs into service, plug them in and check the resistance between their ESD grounding connectors is double that between a single plug's ESD grounding connector and its ground pin.  If there is no resistance between the connector and the pin you *MUST* use ESD leads with a built-in safety resistor.   

Whether or not your outlets are grounded at all or to the same ground can only be definitely resolved by resistance measurements with the breaker(s) in the panel feeding them off, between them, and a ground point in the panel and a temporary test ground rod.   Doing such tests properly requires a good working knowledge of your electrical regulations (US National Electrical Code), and specialised test equipment which is why calling a qualified electrician is recommended if you don't have previous experience and training in performing NEC compliant electrical work.   A rough check can be made with an ordinary multimeter, but if there is a pre-existing fault, dangerous voltages may be present on supposed grounds so be careful and test for voltage difference before doing any resistance checks.  A socket tester is useful as a quick and cheap check that anyone can make that shows you if Line, Neutral and Ground are present at a socket and wired to the correct pins, but it wont find connections that have a higher than normal resistance e.g. due to a loose terminal screw, wirenut or backstab connector + oxidisation on the wire end.

[timelessbeing]

My area is about -15c to -30c this week. The shocks happened when  the temp was about 5 to -10c.

Cold temps make the air dry and it's easier to build up static electricity on your body.

1. Beep sounded when the other probe touched any of the screws

"Beep" means that whatever your probe tips are touching is electrically connected, therefore the screw is grounded. Tighten the screw down onto a piece of wire connected to your strap and you'll be fine.

The electricity supply company's responsibility ends at the meter

Corsair is a PC component manufacturer, not an municipal utility provider.

[eeguy]

The tray the motherboard is mounted on should be grounded, and motherboard screw holes that have a silver coloured ground pad round them should be screwed down to a metal standoff pillar so those screws should be grounded.  However paint is an insulator so it is likely your PSU doesn't ground properly to the case.    Fortunately the 0V wiring coming from the PSU and going to the motherboard and drives is normally internally grounded in the PSU and that will be grounding your motherboard.  Check continuity between the PSU screw you tested to earlier, and a black wire on a spare drive power connector (old style connector not SATA power connector) to confirm that.

Fixing your PC's internal chassis grounding problems could be quite tedious.  It will probably involve a lot of work scraping away tiny circles of paint under screw heads, and/or fitting serrated washers under the screw heads.

I wouldn't trust there not to be a potential difference between two outlet grounds unless they are on the same faceplate or power strip.  However ESD grounding almost invariably has high value series resistors, and potential differences in grounding systems are typically very small, so with no low impedance path between the two grounding plugs other than the ground wiring in the wall, there are no significant risks to you or to equipment.   Before putting multiple grounding plugs into service, plug them in and check the resistance between their ESD grounding connectors is double that between a single plug's ESD grounding connector and its ground pin.  If there is no resistance between the connector and the pin you *MUST* use ESD leads with a built-in safety resistor.   

Whether or not your outlets are grounded at all or to the same ground can only be definitely resolved by resistance measurements with the breaker(s) in the panel feeding them off, between them, and a ground point in the panel and a temporary test ground rod.   Doing such tests properly requires a good working knowledge of your electrical regulations (US National Electrical Code), and specialised test equipment which is why calling a qualified electrician is recommended if you don't have previous experience and training in performing NEC compliant electrical work.   A rough check can be made with an ordinary multimeter, but if there is a pre-existing fault, dangerous voltages may be present on supposed grounds so be careful and test for voltage difference before doing any resistance checks.  A socket tester is useful as a quick and cheap check that anyone can make that shows you if Line, Neutral and Ground are present at a socket and wired to the correct pins, but it wont find connections that have a higher than normal resistance e.g. due to a loose terminal screw, wirenut or backstab connector + oxidisation on the wire end.

Thanks. Is this the device to test if the 3 holes in each socket are wired correctly as expected?

https://www.kleintools.com/catalog/electrical-testers/gfci-receptacle-tester

[Ian.M]

Yes, that will do the job and vastly reduce the risk of you geting a nasty surprise.

That's a luxury socket tester as it also has the ability to test if the circuit's GFCI protected.   You could get away with a basic no buttons 'three lights' one, but its nice to have the GFCI  test button, so if you are happy with the price, go for it.   IMHO every homeowner who's not dangerously DIY-incompetent should have one.

The electricity supply company's responsibility ends at the meter

Corsair is a PC component manufacturer, not an municipal utility provider.

   
I don't expect to recognise the names of N.A. local utility companies and aren't in the PC building biz, so that flew right past me!