Warning for new machine owners – grounding issues

Warning for new machine owners – grounding issues

This is a short warning with information how to solve the issue.
More and more machines are delivered with deadly configuration on the grounding of the electronics.

In China, the electric standard is not well built and many houses still do not have ground solutions in their house. So the machines are built by their standard, when we in EU or US or other parts of the world often have a good ground setup already in our homes since many years.
If you have a 3-prong outlet from your wall, you do not need (and should not) ground it from the ground bolt.

Important information

This guide expect that your ground wiring where you have the laser is up to code.
If you are uncertain your ground are safe in your house – consult a electrician.

The problem

The internal electronic parts are grounded to the ground bolt in the rear of the machine, so is the ground line in the cable you plug to your wall outlet.
But, the bolt itself are often isolated from the machine case which is a big problem, first off for your safety, second for the current regulations and laws about machines with high voltage.
In China they do this because the grounding is external and not inside the cable from their wall outlets. But for us who think the case ground is properly done – it can and will kill you!

Ground bolt on the K40 laser machine with external ground. Not needed if you have proper ground in your wall outlet!

How to identify and fix this problem

Start with removing the ground bolt from your machine.

Use abrasive paper or a knife to scrape away some paint around the hole for the ground bolt. Both inside and outside.

Remove ALL plastic/nylon washers from the ground bolt, only use metal washers.
Some bolts has a plastic spacer, you might need this.
Here is a layout that will give you a good ground connection.

Now mount the bolt in your machine again.
The lock nut will ensure your bolt never comes off again. You can also use loctite or two nuts.

Here is a picture how a good ground bolt is fastened to your machine.
I use two toothed/serrated washers closest to the metal.

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Comments (4)

  • Christopher Merry Reply

    Is this meant for US owners also? House is grounded. Do I need to perform these steps but not use the ground from the post on the machine? I see a loop back to the grounding.

    11 July, 2018 at 05:54
    • HP Persson Reply

      For everyone. You do not need a cable on the outside of the machine if you have 3 prongs from your wall outlet. Just make sure the metal is clean so the ground bolt has proper connection. This is where the ground from the wall is bolted down, it has to be 100% good contact.

      11 July, 2018 at 14:46
  • Ruairi Reply

    I have just installed a new K40 laser in my shed. I intend to do the upgrade once i am confident with using the laser but for now i’ll use it as it is. I have everything connected but noticed (by accident) that there is a slight electric shock coming from the casing. I live in the UK and have a 3 prong plug for the power supply… Can you advise what I need to do? I am not knowledgeable what-so-ever with electric so please use easy terminology. Thanks

    10 September, 2018 at 09:38
    • HP Persson Reply

      Read the electric warning article i wrote a while back, in the FAQ menu. The problem is often the ground bolt in the back beeing isolated from the casing, this is where the ground from the wall outlet should have 100% contact with the metal. Take a look in the article and follow the steps and it will probaly solve your issue. If not, you have bad grounding to your shed.

      10 September, 2018 at 09:43

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