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I had recently purchased an ender 3 and after setting it up and plugging it in, I received an electrical shock from the power supply. I live in the UK and so I was provided an EU to UK adapter which I used and I set the voltage to 230 V.

Does anyone know why I was shocked and if there is any solution? Was it because EU to UK isn’t grounded (or am I wrong)?

Would an older 10 amp monitor power cable work better as it’s grounded?

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    $\begingroup$ Hi and welcome to 3D Printing.SE! Please take care if the mains voltage is considered. Please define shock, you mean a shock from the mains voltage? Or a leaking (low) current giving a unpleasant feeling? $\endgroup$ – 0scar Aug 31 '18 at 15:35
  • $\begingroup$ A low current unpleasant feeling. (Another question) Also like the 3D printer noob that I am; I decided to open up the PSU and after a check everything seemed fine and I put it back. When putting it back I over tightened one of the hex screws; do you think it’ll still be ok despite being a tad loose $\endgroup$ – jb7852 Aug 31 '18 at 16:38
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    $\begingroup$ Using a UK 3 pin plug is probably a very good idea, the weird feeling could be due to poor grounding. If it is a tad loose it is probably ok, but maybe a bit of electrical insulating tape wrapped around could be a good idea to keep it together, so long as it doesn't cover any ventilation holes or end up making the PSU get warmer $\endgroup$ – Greenonline Aug 31 '18 at 16:55
  • $\begingroup$ So the eu cable provided with the printer states 16 amps 250 V on it; is it ok to use a uk 10 amp 250V cable instead then? With the uk one obviously being grounded as well— I’m mainly worrying about blowing the 10 amp fuse at this point. $\endgroup$ – jb7852 Aug 31 '18 at 17:19
  • $\begingroup$ A blown fuse is not a problem and can be easily replaced, so you shouldn't worry about that. Besides as Tom's comment the printer shouldn't draw that much current anyway. If it does blow, then there is something seriously wrong with the printer, and either check the circuits yourself, or if you don't feel comfortable, or confident, to do it, send it back as it will be a sure sign that the printer is faulty. However, the supplier probably just supplied an over large cable/plug $\endgroup$ – Greenonline Sep 2 '18 at 21:35
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You need to take particular care when using plug adaptors - they are not always made to a high standard, and it is possible that the earth connection is not present. If you suspect that the earth connection won't allow a 13 A fuse to blow, it would be good to destroy the adaptor.

A simple cable (without adaptor) will be better, but is unlikely to solve the problem.

You should also check if your mains supply uses an earth-leakage protection circuit (any modern installation must, but your house may predate this legislation).

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The "shock" is likely from noise filtering circuitry at the power supply's input. For filtering, every power supply has a small capacitor that connects the live input wire to ground (a so-called "class Y capacitor"). A small amount of current can flow through this capacitor, which can give an annoying, but otherwise harmless shock/tingle. Grounding the power supply would solve the problem (which you should do anyways, because it is dangerous to run electronics that are supposed to be grounded without ground).

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  • $\begingroup$ So the eu cable states 16 amps 250 V on it; is it ok to use a uk 10 amp 250V cable instead then? With the uk one obviously being grounded as well— I’m mainly worrying about blowing the 10 amp fuse at this point. Also like the 3D printer noob that I am; I decided to open up the PSU and after a check everything seemed fine and I put it back. When putting it back I over tightened one of the hex screws; do you think it’ll still be ok despite being a tad loose $\endgroup$ – jb7852 Aug 31 '18 at 16:41
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    $\begingroup$ @jb7852 Please do not use the comments to ask follow-up questions; instead, make an new question. Yes, it will be OK to use a 10A cable since the printer doesn't use anywhere near 10A. Since it's a British plug you can/should use a fuse in it. $\endgroup$ – Tom van der Zanden Aug 31 '18 at 19:08
  • $\begingroup$ I would be concerned about the screw vibrating loose over time and shorting something out. Probably best to remove it entirely if the PSU still holds itself together. Not ideal, obviously. $\endgroup$ – Tom van der Zanden Aug 31 '18 at 19:10
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An electric shock from a PSU usually means that either the PSU is wired up incorrectly, or the PSU is wired to an ungrounded spot.

Often, Adapters are not grounded or sloppily made. Get yourself a cable with the same ampere rating as the one you want to replace which has a UK plug. If this does not solve the grounding problem, you need to check if the ground wire in the PSU is mounted correctly.

If you can't get a cable rated the same, either use a higher rated one or change the plug on it.

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  • $\begingroup$ I don’t think you can get a 16 amp power cable in the uk. The supplier of the printer just used a 16 amp eu cable with a 13 amp adapter. Can I do the same but with a 13 amp earthed adapter for eu to uk? $\endgroup$ – jb7852 Aug 31 '18 at 18:49
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    $\begingroup$ @jb7852 I suggest to never use an adapter. It would be more sound to reuse the cable and just switch the plug. Ask an electrician if you need help with it. $\endgroup$ – Trish Aug 31 '18 at 19:29
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    $\begingroup$ @jb7852 - You really shouldn't need 16 A fused plug, a standard 13 A fused plug and lead will do. The printer won't draw more than 13 A - If it does then there is probably something very wrong with it (i.e. a short, or a dodgy heated bed). Besides, all ring mains in British houses are 13 A anyway, apart from the cooker (unless you have a special, high current, circuit (16 A or 32 A) installed by an electrician). Commercial/Industrial units have higher current supply circuits though. $\endgroup$ – Greenonline Sep 2 '18 at 21:27
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Check the input cable used, I had similar experience when using cable they provided, then I found out that the plug had swapped L and N wires inside, measuring mains voltage between neutral and ground. Swapped cable for known good and the issue was gone.

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Had a similar problem with my Ender 5, just a 'static like' shock, not continous. Put a multimeter between printer frame & earth with printer switched ON & it read 20+ volts ac continously! With printer OFF there was about 0.5V ac. I connected an additional earth wire from the psu earth terminal to the printer frame & now no more shocks. I can only assume there not a good earth connection between the psu & printer frame but this doesn't explain where the ac voltage is coming from.

ps I also measured current flow between printer frame & earth when the voltage was 20+ V ac & MM showed zero micro amps?

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  • $\begingroup$ on the ender 3, the PSU is screwed to the frame through bare holes, thus connecting the frame to the PSU housing, which is connected to the earth. It seems in your case you might have some isolation between the connecting screws and the frame. $\endgroup$ – Trish May 11 at 20:36
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Yes. The shock from the lack of grounding. Most cheap SMPS (switched mode power supplies) are grounded to the metal casing which, in turn, is connect to the ground terminal where the AC plug is wired.

tl;dr, take the plastic box on the end off an wire in a UK plug that DOES ground the power supply.

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Sorry for leaving this so late, I completely forgot about my account until I went through some old emails. In terms of the PSU shock issue, it was fixed through a replacement 13 A cable from an old monitor (so @Green Online and @Sean Houlihane's response worked best I think).

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