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  1. #1

    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.

  2. #2
    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!


  3. #3
    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.

  4. #4
    Senior Engineer
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    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.

  5. #5
    Engineer-in-Training ServiceXp's Avatar
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    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.

  6. #6
    Engineer Marm's Avatar
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    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.

  7. #7
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    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.

  8. #8
    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.

  9. #9
    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.

  10. #10
    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.

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