Just got KX3 today, turned it on, got an electric shock when touching case

[trialanderror]

Thanks so much, I will give this all a try. So the 3rd ground pin on plugs is important yah? I myself am one of those people that bend it off when I need to use a 2 prong extension cable or what not. Never had problems like this before. I did not touch the prong for this, its actually 220V so shaped a bit different. I will give this all a try. Would a missing 3rd prong be the reason for a shock like this to happen?

[trialanderror]

Also I have always been scared of plugging a $10 thin multimeter wires into 220V, I should be okay to do it yah?

[verohandymike]

Just wondering if what you are getting is a static shock and not electrical. About the only way to know is touch it again after you just got shocked. What you feel as a shock could just be static electricity discharging; in which case it would not happen again if you touch the case a second time. This can also be helped by grounding but I get shocked all the time by properly grounded machines...especially when I am cutting Sintra sheets on a CNC machine; sliding sheets on and off the table produces enough charge to ruin my day when I touch any grounded machinery afterwards.

[trialanderror]

Definitely an electric shock. While the machine is off and unplugged I can hold my finger on a screw holding the case and get a constant buzz. It's weird though since I thought I solved it when I plugged it directly into the wall before, touched every part of the case and no shock, but when i turned it on again the shocks started.

[PriddyShiddy]

several of the switches are installed with screws and I have seen pics of the screws holding the power switch piercing the power wires...

STOP USING THE MACHINE until you locate the grounding/wire issue!! I'm not an electrician, but my dad would smack me with a 2x4 if I told him I was using a machine that shocked me and didn't know why. (he IS an electrician of sorts)

Pull the plug (from the wall) pull the back case off and the switch housing off. The wires aren't very hard to trace. Start by just going over all the wires top to bottom looking for the ones that were melted, pierced, cut, over stripped and contacting something or what ever is causing this.

It is likely something simple that you can see with the naked eye if you look and inspect all the wires. No point dying or blowing your machine without at least looking.

There are 1/10th the wires in these machines as the wheelchairs I service every day... visual inspection of wires and connectors with a BRIGHT flashlight goes LONG LONG way.

[wdbox]

The missing third prong can kill you.

On a typical 220 volt system you have 110 volts from either leg to the neutral. The neutral is generally at ground potential and the green wire is referred to as a safety ground. I would guess that you are using the two hot legs only, no neutral, to power your machine. With this arrangement, any leakage or short from either power wire to your ungrounded machine frame has the potential to kill you. In the worse case your machine frame could be at 110 volts, referenced to ground. Should this occur and you contact the frame and ground at the same time, you will be the current limiter or fuse. Picture what would happen should you stick your tongue and a toe into a wall socket. It makes for a really bad day.

For proper operation and operator safety you MUST connect all metal parts of the machine directly to earth ground. There MUST be no voltage potential between the metal parts and ground.

[Al_The_Man]

I get a small shock even when the machine is off. Could I just ground a screw from the machine case to the ground on the circuit?

The current practice for grounding on machinery especially those that include electronics is something called equi-potential bonding, this is a ground or bonding conductor connected to each metallic section of the machine and brought back to the the same common point as the service ground from your plug or AC source.
From what I have seen of ROC equipment, they rarely conform to this.
In any case leakage should not normally exist from equipment to earth ground even in a properly grounded machine, it would point to some insulation failure.
Al.

[trialanderror]

So from my understanding, if I ground the case by screwing a wire into it and connecting the other end to the main ground, it should stop the electric shock from occurring but there still is likely a problem with one of the 100 or so wire connections inside the case.

I am going to open the case again now and one by one go through the wires. Is this problem likely caused by something that's supposed to be grounded, not being grounded? Or something that is supposed to not be grounded, getting grounded?

Thanks so much for everyones help so far.

[Al_The_Man]

Is this problem likely caused by something that's supposed to be grounded, not being grounded? Or something that is supposed to not be grounded, getting grounded?

.

Sounds like it could be a combination of both
Al.

[trialanderror]

So I opened the case again and did a big look. I noticed there was a green wire attached to the transformer in a weird fasion like it was just dangling but then tugged on it and its secure.




It kind of looks out of place. If anyone else has a KX3 and can see if they have this wire there I would appreciate it.

On the other side of the transformer, there were 2 wires or fabric that were thinner than hair dangling onto the transformer from the screw terminals above it. I yanked these out and tried to test them on the multimeter to see if they are actually conductive but didn't get a result. They could easily be fabric but they were copper color. I am currently uploading a video to youtube that shows these 2 wires, will post when its finished.

Needless to say, when I plugged the machine in again, there was no shock no matter where I touched. It could be one of 3 things:

1: Fluke
2: The hair like thing I yanked out was actually causing the problem
3: The last time I took off the 3 sheet metal pcs covering the electronics, the machine stopped shocking me when I tested it. When I put the case back on, thats when I noticed its still shocking me. Maybe one of these pc's have something to do with it but I doubt it.

Hopefully it wasn't a fluke and will still not shock me when I try it tomorrow. Should I still ground the case? Can I just ground it to any screw terminal on any circuit board that says ground? Can't trace the main power cable without cutting the zip ties holding a bunch of wires together which I rather not do unless necessary. Lastly, can anyone with a KX3 confirm that the sound in my youtube video on the first page is normal?

Thanks again everyone! Will keep you posted.

[Al_The_Man]

This is a bit more info than you need, but it should give you an idea of how to ensure that the proper grounding is in place.
http://www.automation.siemens.com/do.../emv_r.pdf?p=1
Al.

[trialanderror]

Here is the video showing the wire I removed, not the green one still not sure if that is supposed to be there though.

http://www.youtube.com/watch?v=PwK1ppmb-yg]IMG 0138 - YouTube

Should I just get a grounding kit like the ones used for cars (Universal 5 Point HKS Earth Grounding Ground Wire Cable Performance Kit JDM red | eBay) and connect the case to it and the other end to a ground on the circuit?