- Extra PC power cable ($4), like those provided with a PSU or monitor.
- Wire strippers
- Cable cutters
- Pliers (optional)
- Electrical tape (optional)
- $9 ESD wrist strap (optional)
- Multimeter (optional)
Video Walkthrough of Creating an ESD Grounding Cable
Construction Steps & Disclaimer
Standard disclaimer: Although this process is safe (if properly executed) and something we'd rate as “easy” on the difficulty scale, you are still working with electrical components and wiring. If you are uncomfortable doing this, you should seek assistance from someone with more electrical knowledge. Failure to follow these steps precisely can result in electrocution or injury caused by electrical “shock.”
This is a pretty easy process. Our goal is to expose the ground wire's copper to our touch, which will remove any electrostatic charge from the body while building. The cable will be connected to an outlet via the grounding pin only.
Modify the Plug-Side of the Cable
The power cable (take this from an old power supply or similar) must be a three-prong cable, meaning it's got two hot prongs and a grounding prong (cylindrical, fatter). For safety, we want to ensure those hot prongs never find their way into an outlet.
Take your wire strippers (or, ideally, a pair of pliers) and bend the two hot prongs outward in opposite directions. Leave the grounding prong untouched. If the hot prongs snap during this process, get some electrical tape and cover the end that's still connected to the cable header (this is for safety!). The hot prongs are the squared ones and normally have holes in the center of the prong head.
Modify the Connector Side of the Cable
Next, get your cable cutters and locate the opposite head of the cable. The head that connects into the computer or monitor (the “connector”) must be removed to expose the underlying wiring. Use the cable cutters to snap off the connector off of the cable. You can discard the connector head. Scissors can be used for this task if no proper cable cutters are present, it'll just be less clean. You want the cut to be as clean as possible.
This process will reveal the underlying shielding and wiring. Three wires should be present (one for each prong on the socket-side plug): Green (ground for low voltage cables), black, and white.
To get better access to the wire shielding (colored sheath) underneath the cable housing (black rubber), take your cable cutters and remove about one inch of the black rubber housing. To do this, we normally have to cut four small incisions around the perimeter of the housing, at which point the last inch of housing should be easily slid off of the shielded wires. The removed inch can be discarded.
During this process, be careful that you don't cut so deep as to cut through the underlying wires. You should be cutting a very shallow incision that's only enough to remove the outer housing.
Modify the Underlying Wires
We've now exposed the three wires to open air. Bend each of the wires slightly away from one another (think: Creating the wireframe of a 'pyramid'). This is to isolate the wires to ensure no incorrect cuts or mistakes.
Snip the Black and White wires near the base. These are the “hot” wires and are unwanted for a simple grounding cable. If you want to be safe and/or clean, tidy up the ends by covering them with electrical tape. This is not necessary, but not harmful.
You should now have one wire sticking out from the end – the grounding wire, which is green. Take your wire strippers and match the right size to the outer shielding of the copper wire. Strip the green shielding away from the copper; do not cut into the underlying copper. We only want to remove the outer housing, not the whole wire. Expose any length you like. We usually expose about a half-inch of copper. If wire strippers aren't doing it, make a very tiny, careful incision with a cutting tool (razor blade, scissors, cable cutters).
If there's some fraying or straggling copper wires, take the end of the wire and twist it clockwise. The copper wires are fragile and will best survive use by being twisted together.
Testing the Grounding Cable (Optional)
This step is optional and requires a voltmeter or multimeter.
Take your multimeter and set it to check for resistance (Ω ohms). Take the probes and make contact with the ground pin and the exposed copper. Your multimeter should indicate continuity (on ours, this is displayed with quad-zero, or 0000 Ω, but some beep – read your manual).
If continuity is reported from the ground prong to the exposed copper, we know that the correct wires were cut for grounding use.
Using the Grounding Cable to Prevent ESD
We have a lab with hardwood floors to reduce build-up of static electricity. To this end, we're fairly comfortable tapping the grounding wire for intermittent grounding rather than remaining constantly attached. Your use case will depend on your comfort level and environment.
Above is a photo of how we've mounted our GPU bench grounding wire. A screw protrudes from our video card shelving unit (which sits next to the bench), and we've twist-tied the grounding cable to that screw. When we're ready to replace GPUs for the next test, we just grab the exposed copper for a second before proceeding.
For those who want more constant ESD protection (working in a cold and dry environment or on carpet, for instance), we'd recommend clipping your ESD wrist strap to the exposed copper. This will keep a constant connection to ground while building.
The other end – the plug end – must be connected to an outlet in order to work. Again, only connect the cylindrical ground prong (the other prongs should be bent to a point of impossible connection, anyway).
That's it! Just remember to tap the wire (or connect via strap) before working with any electrical components – laptop internals, motherboards, CPUs, whatever – and you'll have some assurance that you've been grounded. It is still possible to discharge static electricity into a component given the wrong conditions, like building on an insulating surface, building up a charge by shuffling your feet on carpet, or just working in cold/dry atmospheric conditions. That said, the chance of damage caused by ESD is reduced substantially by building a cable like the one we've described above. Speaking strictly personally, I've yet to kill a component (or cause latent ESD) by using this method – and we'd definitely killed components in the lab back before we were ESD compliant.
This process provides a direct path-to-ground to ensure your static charge exits your body. Just clipping the ESD strap to a case -- which is normally painted metal (non-conductive) and doesn't have a direct ground path -- isn't going to offer assurance that static electricity has been eliminated. Short of this approach, the next best thing would be to connect a PSU to the outlet, disable the power toggle on the PSU (set to '0'), and clip your ESD strap to the PSU fan grill housing; it's not perfect and that's still somewhat non-conductive, painted metal, but it's better than clipping to the case. Our above cable creation, however, is the best possible solution and almost anyone can make one.
Let me know if you have any questions below. We also welcome inquisitive minds to our forums, where we offer free, expert, one-on-one system build help.
- Steve “Lelldorianx” Burke.