VoltAlert picks up desk lamp from 50 cm away, crashes printer

[mixiom]

Hello! On my desk is a desk-lamp and a 3D-printer ("Ender"). The moment I switch the lamp on or off, many times the 3D-printer crashes and restarts. The desk-lamp is a "Class II appliance", meaning it does not have a earth cable. The VoltAlter function of my multimeter, which senses AC voltage, beeps at 50 cm distance from the desk lamp (off), which to me indicates a nonexistent shielding. My theory is this: the unshielded cable of the desk lamp makes its metallic arms act as antenna. When the lamp is turned on/off, change of current increases that electric field and the 3D-printers mainboard, which does only have a plastic case, picks up that field and overloads/crashes. I omitted that other devices on my desk, for example a lab power supply, also at times cause the printer to crash at turn on/off events.

Is this reasonable thinking? I also wonder if there is a elegant solution. At the moment I am thinking about a DIY metal enclosure for the printers mainboard, that seems best, or am I missing something?

[Manul]

There is something wrong with 3D printer board. It should not be so sensitive. Maybe some digital lines are floating or pullup resistors are too high value. Maybe it picks up interference from external wiring, maybe some wire is disconnected. Hard to say, only you could investigate.

[mixiom]

Is there a nice way to trigger such interference related problems in a controlled way, without having to turn my lamp on/off hundreds of times? I am not sure how to actually investigate the matter.

[SmallCog]

Does moving the 2 apart have an affect?

[Vtile]

As above.

Are the lamp using a tungsten lamp or some energy saving bulb? If you measure the lamp metal frame with voltage meter it does propably have several tens of volts of potential difference to ground. This is normal for a such lamps and the value depends the input impedance of meter. If you then connect a meter with current measurement (equivalent to short circuit) between ground and lamp body it should read zero or a few microamps.

[Terry Bites]

Have you tried a Common mode ferrite on the lamp lead? https://www.google.co.uk/url?sa=i&url=https%3A%2F%2Felectronics.stackexchange.com%2Fquestions%2F320733%2Fwhat-exactly-happens-to-the-signals-hitting-a-common-mode-choke&psig=AOvVaw02DMe3MyFMa51jNWXIUwCR&ust=1644576793979000&source=images&cd=vfe&ved=0CAgQjRxqFwoTCKiHj4_89PUCFQAAAAAdAAAAABAF