Author Topic: K40 grounding questions.  (Read 77 times)

Network23

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K40 grounding questions.
« on: November 10, 2017, 05:12:36 PM »
Hope this is the right spot for it.

So there is a ground connector. I have read 2 things, 1) you don't need it since the plug has a ground, and 2) You need a ground.

 Is this what I would need: https://www.homedepot.com/p/ERICO-5-8-in-x-8-ft-Copper-Ground-Rod-615880UPC/202195738

 How deep does it need to go into the ground, what kind of wire does it need, how do I mount the wire? Is wrapping wire around it and into the back of the laser enough?

ThothLoki

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Re: K40 grounding questions.
« Reply #1 on: November 10, 2017, 06:33:09 PM »
Um...no. I doubt you need that unless you want to ground your entire house in the process.

I do not have a K40 but am in the electrical trades and have to take grounding classes every 2 freaking years.

Can you post a picture of what part you are wonder about grounding?

The PSU should be grounded. All electrical components with a ground lug should be grounded. When you plug it into the wall (hopefully with a ground plug), it will ground your machine to earth (or house) ground. You should just have to ground the other components to the chassis of the K40 and then you should be good.

BTW, that grounding rod is what your earth ground is connected to for your electrical wiring. Generally people buy them to add a ground to something like a satellite dish
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laser_cutter

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Re: K40 grounding questions.
« Reply #2 on: November 10, 2017, 06:59:29 PM »

ThothLoki,

One of the instructions with thise K40 is ground directly to earth. There is debate as to whether that rod is needed vs just a regular US 3 prong plug.

I believe there is a small screw on the case of the K40 that one connects the earthen ground too. In another post Zax mentioned earthen ground.

ThothLoki

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Re: K40 grounding questions.
« Reply #3 on: November 10, 2017, 08:09:39 PM »
The three prong plug goes to earth ground aka you electrical panel ground. That is connected to the main power supply which is attached to the frame.

Everything that needs grounding goes to the frame, which is an extension of earth ground.
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Zax

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Re: K40 grounding questions.
« Reply #4 on: November 11, 2017, 04:02:17 AM »
Just make sure you have a good ground (earth) connection from the machine chassis to the grounded outlet. You don't need and should not make a new ground.

Network23

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Re: K40 grounding questions.
« Reply #5 on: November 11, 2017, 06:59:08 AM »
This guys video scared me.
https://www.youtube.com/watch?v=6vztMvWUnmM&feature=em-comments

Also the grounding confusion is what made me not buy it and go with an A3 in the first place.

ThothLoki

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Re: K40 grounding questions.
« Reply #6 on: November 11, 2017, 07:11:42 AM »
Never make a new separate ground. You want the machine at the same potential at your house. That is what keeps you from getting zapped (that and insulation)
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laser_cutter

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Re: K40 grounding questions.
« Reply #7 on: November 11, 2017, 07:57:34 AM »
This guys video scared me.
https://www.youtube.com/watch?v=6vztMvWUnmM&feature=em-comments

Also the grounding confusion is what made me not buy it and go with an A3 in the first place.

The person who made the video "I am not an electrical expert"



Landbo

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Re: K40 grounding questions.
« Reply #8 on: November 11, 2017, 08:12:30 AM »
This guys video scared me.
https://www.youtube.com/watch?v=6vztMvWUnmM&feature=em-comments

Also the grounding confusion is what made me not buy it and go with an A3 in the first place.

With all respect, that man do not know what he is talking about. Make sure you have GND in your wall outlet and do not lift the doors in the right side to the electronics as well as putting your fingers in the cooling water while there is voltage on the machine. If you comply with the two rules, the K40 is as safe to operate as your washing machine in terms of electrification.   ;)

Regards Leif.
« Last Edit: November 11, 2017, 08:22:25 AM by Landbo »
Only a new "Wood Smoker"  /;-)

Stonemull

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Re: K40 grounding questions.
« Reply #9 on: November 11, 2017, 08:17:19 AM »
edit: above posts were entered while I typed this spiel lol.

That video is done by somebody on the paranoid level of safety conscious. There are many faults in both his methodology and what he says, however I commend him for warning people.
While what he says is mostly true, your house earth and regular plug should be quite sufficient, 23mA is probably not going to kill you, though it might if all the conditions are just right and you have a weak heart,  it would bloody hurt at best. Fatal currents are typically listed as 50mA for a healthy person.
If you want a safety backup, sure, connect another wire to an earth rod, it does need to be there so doing it to code is not required, you are not trying to earth away a 20A mains current like the regular house earth can do, so going 8 feet deep is not needed, a blade of grass touching an electric fence reduces its zappines a great deal, this is much the same though more dangerous, however even a decent sized tent peg into damp soil woukd do the job.
His 12 ohm resistance to earth is likely due to the shitty aligator clips he is using, they are not soldered from new and rely on wire touching the crimp, I solder them when I buy any, even then, oh no, 12 ohm resistance ! at 23mA that works out to 276mV .. even with his 'faulty' earth and the laser supply connected to the case you could lick it while holding an earth rod and not feel a thing.
I assume he has his cathode connected to ground, I am not sure if thats how these lasers are assembled .. it should return back to the supply not to chassis earth.
Even if the laser cathode is ground and the entire case is floating (unearthed totally)  then the zap you get is effectively with the laser in series with the current, this limits the current and the voltage.
He reckons you die if your unearthed pump shorts to mains, yeh .. not really, you will get a punch and take your hand out the water, been there done that with a 240V immersion heater with bad insulation in a steel drum .. had worse zaps from a light socket, the water limits the current mostly, one thing with movies when they chuck a toaster in the bath .. its probably not going to hurt fatally unless its a metal bath tub that us earthed by the drainage, or an insulated tub and your toe is on the metal drain.
In short .. this guy is talking up the risks to get his point across, or he is the type to wear a crash helmet in the bathroom in case he slips over.
These lasers are not as dangerous voltage and current wise as a microwave oven unless there is some seriously bad design issue regarding the grounding I am not aware of. A microwave oven could zap you dead so badly your pets die as well, i don't see anyone running them with an extra earth rod though.




« Last Edit: November 11, 2017, 08:18:34 AM by Stonemull »
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