Possible dangerous electrical issue... Please help.

I recently purchased a kit from Electron 3d, which is just a clone of the Migbot from what I hear.

After a lot of troubleshooting I was finally getting some pretty amazing prints, but tonight I ran into a problem I can't seem to figure out. About and hour ago I noticed when my finger/skin was near the hotend tip of the extruder that I could "feel" an electrical field (kind of like a hum) from about 2cm away. This was interesting to me, but I guessed I had just not noticed it before, then about 30 minutes later, for the first time, I touched the metal housing on the extruder and it shocked me. It felt like a static shock, but I touched it a second time and it shocked me again (I had not even moved, so it couldn't have been static.)

I noticed after the shock that the LCD display was scrambled (which happen occasionally when I update the firmware) but the printer still works fine. I'm sure if I were to plug it back in, the screen would show it's normal text, like if I did a hard reset after updating the firmware.

My issue is, I don't want to turn on the printer if there is a grounding issue, which I don't suspect there is considering I haven't had this problem until now. I know the PSU is grounded, as I replaced the cheap cord included with the kit with a properly polarized and grounded computer power cord, and the connection between the cord and the PSU hasn't been touched/moved/breathed on since it was installed (made sure it was secure before the first power on as well by tugging on the cable connections, which were firm.)

I have fixed every problem this kit has thrown at me, but this one scares me. I am worried that, since the issue has just spontaneously degraded to where it is now, that if I play with it too much it could become a hazard and I might get electrocuted.

Does anyone have a clue what I could try? Is there any additional info you need?

Thanks in advance.

Definitely sounds like a ground issue. And obviously it needs to be sorted out ASAP!!

No joke, people have had their houses burn down due to poorly wired 3D printers.

When you say housing what do you mean exactly? A housing near the hot end? If yes, and you don't get a shock anywhere else, then it should be relatively easy to back track as the aren't too many wires in that area...

Be safe!

Yeah, the bent metal bracket that you bolt the extruder parts to (the stepper motor, heater block, fans, etc.) is what I got shocked by.

I was honestly too afraid to touch any other part of the printer, so I can't say whether or not it was localized to that area.

Was thinking maybe the heater block "humming" when I put my finger near it has something to do with this, and maybe there is a short in the heater itself, however there are no visible wire breaks, and the wires are not touching, and they are connected solidly to the heater. However, it is the only high amperage component in the heater block (the only other electrical component being the thermistor), so it is the only thing that could be causing the problem if it's only that specific area that shocks me.

I guess I will try to see if it shocks me anywhere else tomorrow, though honestly I am scared it could electrocute me.

Just because it is high amperage does not mean it can shock you at all, there is absolutely no relationship between the two.

You need to start at the plug, make sure what you think is live actually is live. Check the earths at the plug and follow the earth all the way back to the head.

Unplug it from the mains and use a meter or battery and bulb to make sure that all the metal work is connected to the earth pin.

It is all pretty standard stuff and in truth of you cannot trace an earth fault or satisfy yourself that there isn't one then you should not be making things that plug into the LV supply.

As other have stated, you definitely have some leakage somewhere. You may want to install a GFCI outlet for future (you need to sort this out first) protection.

As mentioned, most likely a grounding issue. Make sure your grounded plug is actually grounded. Get yourself a multimeter, or if you're unfamiliar with those, contact somebody familiar (ie licensed/trained) with electrical work to help.

Without being there to see it is hard to be sure but do bear in mind that plastic sliding in a plastic tube does generate a static charge. Just thought it worth mentioning in case that is your problem.

Unfortunately that is not my problem, as I don't actually have any tubing for my filament. I am at work so I am unable to check the ground fault. I am familiar with using a multimeter. Mjolnir I was shocked by it. I was not implying that there was a relationship between the amperage and the voltage as far as getting shocked goes. I do not know how many amps the current was at (I assume not many as I am still alive), but I was definitely shocked, twice. I will see about the leakage issue when I get home.

I just didn't want to plug it back in if there was a chance it was going to hurt me, damage the equipment, or destroy my house. lol. I'll see if I can get some pics up after work, and I will post the results after I check the ground connection.

Okay, so after using the multimeter I can confirm that my electrical socket is wired correctly so that's not the issue. I tested for voltage coming off of the printer when it is plugged in and if I don't switch the heater on it stays at about the background voltage levels, but as soon as I turn the heater for the extruder on, the voltage climbs (almost like a capacitor) in every part of the printer that is connected to power, to about 1.7 volts AC. I am not sure if it will hold more, because 1.7 volts doesn't seem like it would shock me, but I could be wrong. I made sure it wasn't an error with my multimeter by testing unground screws in the acrylic frame, and they all read the background voltage (natural free voltage), but as soon as I touch any metal on the machine that is connected to power, it jumps instantly to 1.7 volts. What's really strange is that after I turn off the heater, the voltage lowers slowly, last I looked at it it was 1.2 volts. So it is charging and discharging a lot like a battery or a capacitor every time it is plugged in.

Looks like it has capped out at about 1.95 volts now. Seems directly tied to how hot I have heated the heater. 1.7volts at 180C and 1.95@210C Edit: indeed it is actually tied to how much power is needed by the heater. I turned it off, the power drops, if it needs to hold a certain temp it stays at 1.95 when fully charged, and when it is heating it can get all the way to about 2 volts. And as I said, this is measurable from anywhere there is an electrical connection to a component, but the voltage is directly tied to the power the heater is receiving.

Ok, So if you disconnect the heater you get no leakage? What kind of heater? Pictures?

Now I am really confused. So, just to be clear, the printer still works, it is having no issues, however, every part of the system that should be well grounded, has a positive voltage between 1.5 and 2 volts depending on where I am testing. It no longer appears (could have just been a coincidence) that the voltage is related to the power needed for any of the heat elements. It is just there on the whole printer.

I tested the grounded shield on the usb plug on the RAMPS board, and it was the highest at about 1.97 volts, the aluminum bed was 2nd @ about 1.88 volts, the lowest were the rails, which were between 1.00 volts and 1.56 volts.

The LCD screen is particularly higher than most things, with just the screws that secure it being measured at about 1.9 volts. So, yeah, I don't know. And it is AC voltage as well, but I have double and triple checked my connection to the PSU, and it is correctly wired with secure connections. Besides, if I had wired that incorrectly wouldn't those parts be 120 volts, not 2? Ugh, This is frustrating. And as I said earlier, I checked the polarity and grounding on my wall socket with the multimeter, and it is indeed wired correctly.

So, just a question I really want answered. Let's say I did wire it in reverse, I.E. I switched L and N. Wouldn't the voltage coming out of the supply charge the neutral parts to 120 volts? Or is it possible that it would be 2 volts? The reason I am asking, is because I was looking THROUGH the cage on the PSU, and noticed that the N L and G slots are not labeled the same on the inside, as they are on the outside.

This is how it is labeled on the outside (the part I am supposed to read to know how to wire it)

|N|L|G|

and how it looks on the inside of the cage (printed on the PCB)
|L|N|G|

So it is either mislabeled, and wired in reverse (if it is possible to end up with 2 volts in the frame), or it is something else entirely.

EDIT: Also, would the Board still boot up if wired in reverse?

Simple,.... Reverse and test. That is why I asked the question about testing the heater disconnected.

I am nervous, because I have heard of peoples boards frying when connected in reverse, so if it is mislabeled it will work, but if it's not it could break it right?

Nevermind, I think it is correct. I read some conflicting information on color codes for ac power. Just to be clear. White = neutral, Black = line, Green = ground. correct?

So I guess the question is, what do I do next? I can't seem to pinpoint the source of the leak.

If everything is wired and grounded correctly, you need to isolate each component to find the one that is leaking.

To be honest, at this point, I think the voltage I am seeing (considering the background voltage is anywhere between a half of a volt, and 1 volt, that the 1.5-1.9 volts I am seeing is just induced voltage from the components. I mean, I can touch the frame while it is on and it won't shock me. I am just really confused. I guess it could just be a combination of induced voltage and the crappy OEM PSU that was included with my kit. Do you think it would be a good idea to try out a different power supply, like an ATX PSU?

I really don't know what to do now. I mean, there must be a leak, because I assume that if it is properly grounded, the voltage in the multimeter would have to be pretty darn close to 0, as the induced energy would still flow to ground, but it flows steadily through the multimeter and so I just don't know.

EDIT: I did want to add, that by disconnecting the components I did, that the voltage did drop a bit, which is why I think it is induced from the wiring and components, as each component I removed dropped the voltage slightly every time. So, it's not any single component.

Try this...... Remove all the secondary connections from the PSU. See what you get.

You mean the DC output to the Ramps board?

all outputs.

The only output from the power supply was to the Ramps board, which then takes the DC voltage from the PSU and distributes it to all the other components.

But yeah, when I disconnected the DC output I didn't see much of a difference. It's a bit lower, but not by enough to say that it was anything other than background/inductance

Kind of scary then, to think that this thing may just short out and shock me every now and then. And I am absolutely sure I was shocked, and it wasn't just static, because when you discharge the static the first time you are at the same energy potential as the object that you touched, so it wouldn't have shocked me again a half second later. The shock felt almost exactly like static though (both times), so it wasn't a very strong shock.

Unfortunately I only get shocked where I have to grab to put the filament in, which means I will probably get shocked quite a bit. I haven't tried touching it since I got shocked, so I may just hook everything back up, and then try to load some filament. If it shocks me, I know something is definitely wrong.

You need to install a GFCI outlet for that printer.. You have a problem, and until you sort it out you should not let anyone around that machine, and certainly don't leave the unit plug-in unattended.

You should not be getting cabinet voltage (> then say 500mv) to ground period. If the only thing that is plugged into that PSU is power input and the wiring is correct and your still getting high voltage to ground from any component on that machine, I would replace the power supply.

Oh and I forgot to say... measure the outlet between neutral to ground (don't make a mistake here, if your plug is polarized it will be between the large slot and ground). Your meter should be in the mv range. Use that as your base line.

I don't understand how the components could have any voltage (aside from the voltage in the air) without the power supply plugged in. This whole situation baffles me. So you are saying, you want me to measure the voltage between Neutral and Ground to get a good baseline ground reading? Use that as my zero point essentially? Or are you saying, if that measurement is above 500 mv that the ground is not set up properly? I have a gfci plug in the kitchen, should I try that one out? Will it just trip if the ground is not correct? Or will it trip in case something goes wrong, so that I don't have to worry about getting electrocuted. Is there a solution to this problem? lol

I just tested between Neutral and Ground and I am getting about 675 mv which is about what is floating around in my machine. I do live in a dry climate, so maybe static charge is a big factor here

Did a little reading, apparently this is a pretty good value. It should be no higher than 3 volts am I correct? 3 volts on 120v AC corresponds to about a 3% voltage drop, which is acceptable, I measured .675V

You need to either go and learn about voltage and electricity in general or you need to take it somewhere and have them look at it.

The measurements you are taking are totally meaningless and provide no information
You cannot have a positive AC voltage.
You should be measuring the resistance of things with the printer unplugged.
3% voltage drop on 120 is 116.8 volts or so.

As a general rule you cannot feel anything less than 50 volts, this is why telephone systems use 50 volts.
It is extremely rare for anything under 100 volts to cause death.
Just because your filament is not in a plastic tube does not mean you are not developing static. If plastic moves against anything at all then an exchange of electrons and ions will take place.

Is your DC negative rail connected to your house ground wire?
Does your house have an earth spike?
Is your house connected to a PME system?
Do neutral and ground connect together at your meter?

Quote:

---

Originally Posted by masterchafed

I don't understand how the components could have any voltage (aside from the voltage in the air) without the power supply plugged in. This whole situation baffles me. So you are saying, you want me to measure the voltage between Neutral and Ground to get a good baseline ground reading? Use that as my zero point essentially? Or are you saying, if that measurement is above 500 mv that the ground is not set up properly? I have a gfci plug in the kitchen, should I try that one out? Will it just trip if the ground is not correct? Or will it trip in case something goes wrong, so that I don't have to worry about getting electrocuted. Is there a solution to this problem? lol

---

1) Don't pay any attention to any (voltage) values measured with the unit unplugged, it's just a waste of time and is of no value.
2) Used as your base line (empty socket). So values above that is where your attention needs to be focused on.
3) It will do both. The GFCI will monitor the current between Line and Nueteral, if there is any imbalance it will fault and break the circuit to the machine. I suspect (if you truly have a component leaking voltage) your printer will just trip the GFCI when used.

Quote:

---

Originally Posted by masterchafed

I just tested between Neutral and Ground and I am getting about 675 mv which is about what is floating around in my machine. I do live in a dry climate, so maybe static charge is a big factor here

Did a little reading, apparently this is a pretty good value. It should be no higher than 3 volts am I correct? 3 volts on 120v AC corresponds to about a 3% voltage drop, which is acceptable, I measured .675V

---

Forget about the base value, there are a lot of reason that number will be higher and lower at any given time. You are more interested in using that value as your base. I would think, (if it is truly static electricity) after you shunt to earth (discharge the static build up) you would not get repeated shocks. I don't know your setup, but generally static doesn't build up to those levels given the surface area of the filament and tubes. You are much more likely to build up on your body just walking to the machine on carpet. Not only that, I don't think you would be measuring AC voltage with your meter to ground when the unit is running if this was a static issue.

Quote:

---

Originally Posted by Mjolinor

You need to either go and learn about voltage and electricity in general or you need to take it somewhere and have them look at it.

As a general rule you cannot feel anything less than 50 volts, this is why telephone systems use 50 volts.
It is extremely rare for anything under 100 volts to cause death.

---

Depending on type (AC vs DC), you can most certainly feel current to ground with much lower voltages. It just depends on how well you are grounded and the current involved. I've had the piss shocked out me with 12vac before. (HVAC/R HA Tech.) As you know, voltage is almost irrelevant in terms of fatalities. The body type, and area of body being effected with the amount of amperage plays a much greater roll in life or death.

Quote:

---

Originally Posted by ServiceXp

1) Don't pay any attention to any (voltage) values measured with the unit unplugged, it's just a waste of time and is of no value.
2) Used as your base line (empty socket). So values above that is where your attention needs to be focused on.
3) It will do both. The GFCI will monitor the current between Line and Nueteral, if there is any imbalance it will fault and break the circuit to the machine. I suspect (if you truly have a component leaking voltage) your printer will just trip the GFCI when used.



Forget about the base value, there are a lot of reason that number will be higher and lower at any given time. You are more interested in using that value as your base. I would think, (if it is truly static electricity) after you shunt to earth (discharge the static build up) you would not get repeated shocks. I don't know your setup, but generally static doesn't build up to those levels given the surface area of the filament and tubes. You are much more likely to build up on your body just walking to the machine on carpet. Not only that, I don't think you would be measuring AC voltage with your meter to ground when the unit is running if this was a static issue.




Depending on type (AC vs DC), you can most certainly feel current to ground with much lower voltages. It just depends on how well you are grounded and the current involved. I've had the piss shocked out me with 12vac before. (HVAC/R HA Tech.) As you know, voltage is almost irrelevant in terms of fatalities. The body type, and area of body being effected with the amount of amperage plays a much greater roll in life or death.

---

You are going to be confusing this guy. This needs sorting with it unplugged.

Current cannot flow without voltage and under normal conditions you need at least 50 volts for it to flow through a human. The most important thing regarding mortality rate is the path the current flow takes not the current. 2 ma through the heart will easily stop it dead but finger to finger on the same hand 3kv will be little more than a tingle and around 2ma will flow .

Death from electrocution is almost always where the current path goes through the heart. If you die from a non-through the heart shock then it is a terrible death that doesn't happen for days after the accident. Death occurs because the muscles are cooked and you will wake up feeling fine, over a few days your body begins to ache and you become unable to move. Fairly quickly after that you will die because your blood has congealed.

This is why they teach you to keep one hand in your pocket when messing with live cables. It is very unliklely that current will pass through the heart if you do not have the voltage across your chest.

Quote:

---

Originally Posted by Mjolinor

You are going to be confusing this guy. This needs sorting with it unplugged.

Current cannot flow without voltage and under normal conditions you need at least 50 volts for it to flow through a human. The most important thing regarding mortality rate is the path the current flow takes not the current. 2 ma through the heart will easily stop it dead but finger to finger on the same hand 3kv will be little more than a tingle and around 2ma will flow .

Death from electrocution is almost always where the current path goes through the heart. If you die from a non-through the heart shock then it is a terrible death that doesn't happen for days after the accident. Death occurs because the muscles are cooked and you will wake up feeling fine, over a few days your body begins to ache and you become unable to move. Fairly quickly after that you will die because your blood has congealed.

This is why they teach you to keep one hand in your pocket when messing with live cables. It is very unliklely that current will pass through the heart if you do not have the voltage across your chest.

---

1) You are probably correct on me confusing the guy..

2) Thanks for the detail, I do understand the reasons for mortality as it relates to death by electrocution and is the reason why I said "The body type, and area of body being effected.." However you are simply wrong when you make statements like "you need at least 50 volts for it to flow through a human". Forget all the safety training I've had that says otherwise, I have felt it first hand. All it took was a knee on damp concrete and my hand bumping a 12vac relay signal (high voltage was off, but control circuits were still powered) to get my attention REAL fast.

If you are going to quote me please quote me correctly.

The statement "you need at least 50 volts for it to flow through a human" is not complete. Please learn to read and reply in a sensible manner if oyu are going to bother replying at all.

I am not trying to educate you I am trying to help the guy with the problem. It seems to me that you cannot be educated as you seem to think you know everything.

Here is my reason for knowing what I am talking about. I have a first class honour degree in electronics. I have a Phd in electronics specifically in the area of electricity distribution networks. I have worked for 25 years in the electricity utility field.

Now I have finished with this thread, I will not post again. You obviously know everything so you fix it but I would appreciate it if you did not kill the guy.

Quote:

---

Originally Posted by Mjolinor

If you are going to quote me please quote me correctly.

The statement "you need at least 50 volts for it to flow through a human" is not complete. Please learn to read and reply in a sensible manner if oyu are going to bother replying at all.

I am not trying to educate you I am trying to help the guy with the problem. It seems to me that you cannot be educated as you seem to think you know everything.

Here is my reason for knowing what I am talking about. I have a first class honour degree in electronics. I have a Phd in electronics specifically in the area of electricity distribution networks. I have worked for 25 years in the electricity utility field.

Now I have finished with this thread, I will not post again. You obviously know everything so you fix it but I would appreciate it if you did not kill the guy.

---

Why so defensive? I wasn't challenging your intelligence, but hey if it makes you feel better to attack others in an internet conversation because people don't agree, well..... As for "...I would appreciate it if you did not kill the guy." you do realize that he built from kit right?

IN situations like this I give my mate acall - he's an industrial electrician and he'll fix it.

So if you don't know what you are doing - find someone who does and let them get electrocuted instead of you :-)

Here's one for you LOL


Attachment 8092

another...

Attachment 8093

Another... I have a feeling, this is Mjolinor feelings toward us (me specifically)... (It's a joke Mjolinor, I'm just kidding......)

Attachment 8094

Just a thought here, I'm not an electrician or EE but have maintained a house for 40 years...

Try plugging your printer into a different circuit than you are currently using (i.e. one in a completely different part of the house not on the same breaker). You may have a hot and neutral or neutral and ground crossed somewhere in the circuit. I had a similar problem once- a slight but definite tingle while touching a light fixture housing during a bulb change. Took me a long time to find the culprit, but a neutral had worn off insulation in a bathroom exhaust fan due to vibration and was touching the metal housing.

Could be something as simple as changing the circuit you are using could fix the problem with your printer.