I have a problem with the house lights flickering when the Sparkx i7 hotbed is heating, Have had an electrician check the house wiring, the earthing etc. I have tried using it from different outlets with the same issue. I have tried running through a UPS, an EMI with no success.
When checking online the hotbed uses PWM for heating, some operators change or insert a extra line into the firmware to counter the problem, however this is not an ideal option unless Creality can do something with an upgrade option that can be uploaded.
The hot bed on the i7 is rated for 600 watts on the 220 volt version and even less on the 110 volt version. That should not make your lights flicker in your house. It means you have a high impedance electrical installation. Maybe some contact resistance is too high in a distribution panel or so.
As a heated printbed is a resistive load, it also doesn’t have high peak currents, which for example, an inductive or a capacitive load like a large electrical motor or so would have.
That could explain why the flicker is visible. Some LED bulb drivers are much more sensitive than others to small, repetitive voltage fluctuations caused by rapidly switched loads such as a heated bed.
I see something similar with my Keurig coffee maker. Some LED bulbs flicker when its heater cycles, while others on the same circuit do not. That points to an interaction between the switched load, the circuit impedance and the design of the individual LED driver rather than proving that either device is defective.
I have a few Kill-A-Watt meters around my workshop, they are useful for checking overall voltage, current and power draw, but it probably will not capture the short repetitive disturbances causing the visible flicker. For that, you would need an oscilloscope or power-quality analyzer which in my opinion is simply not worth the effort. It would only confirm the theory above.
If the electrician confirmed that the wiring, neutral connections and voltage remain within specification while the bed cycles, I would first try a different brand or design of LED bulb. I would not modify the printer firmware unless Creality provides or supports the change.
At the end of the day, I would classify this as an annoyance not a safety or product issue. For my Kitchen lightbulb on the same circuit as my Keurig, I simply tried different bulbs until I found one that wasn’t sensitive. I can’t remember which brand worked, you’ll have to experiment.
