I just bought an air ionizer which claims to putting out "negative ion" to the air to make dust attracts to grounded surfaces, I plug it in for a while and found out when I touch a metal plate (the plate did not touched the output of the air ionizer) I get a zap off it, this never happened before.

So I imagine if this high voltage charge get onto PCB or some sensitive electronics which is not shielded in the same room, it might damaged them if I touch it because all the high voltage get discharged through my hands?

I've searched to see if anyone talking about this but all I've found is "ionizer help discharge ESD which use in electronic production".. but since I just get a pretty strong zap from just touching a metal plate, I doubt about this, maybe I'm misunderstood something?

So, is it recommended to put this air ionizer in the same room which I usually working with bare PCB, electronics that may or may not have ESD protection?

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    \$\begingroup\$ Bare PCBs will be safe. \$\endgroup\$ – Andy aka Feb 8 '18 at 9:41
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    \$\begingroup\$ There are air ionizers which are used to prevent build up of static charges. A place where I used to work had them above workplaces where sensitive devices were assembled and repaired. So, an ionizer doesn't necessarily have to cause static charges \$\endgroup\$ – JRE Feb 8 '18 at 12:02

I'd be concerned having one of those too close to my electronics for an entirely different reason.

I used to have a couple of those and they worked ok but after a number of months I found that the walls and other objects within a meter or so were accumulating large amounts of dirt. Charge build up on the walls was attracting almost as much stuff as the receiver in the cleaner. Since we smoked at that time, the build up was a mess.

Having that kind of accumulation inside your circuits would be a bad thing.

As for ESD. If your electronics is grounded, charges should not build up on the circuitry itself. If the air is ionised enough any charges built up on plastic parts will leak away to the grounded circuitry. If no grounding exists however, static can build up on the entire unit though discharge strength should be reduced in the ionised air.

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  • \$\begingroup\$ Since we smoked at that time I wonder how many ionizers it would require to "clean" the air with a couple of people smoking in the room. I guess, many ;-) \$\endgroup\$ – Bimpelrekkie Feb 8 '18 at 13:59
  • \$\begingroup\$ @Bimpelrekkie yup, they didn't really work that well.. just made a mess, and made the air smell "funny". \$\endgroup\$ – Trevor_G Feb 8 '18 at 14:08

The "zap" you felt was caused by a difference in charge between you and the metal plate. That is an ESD (discharge) event. It happens all the time so it will have happened before but probably the difference in charging levels was so small that you didn't notice before. This also changes with the air humidity, at this moment it is cold and dry here in Western Europe so we suffer from stronger ESD. When it is more humid the charges can easier balance out so the ESD events will be weaker.

So I do not think the ionizer is related to this. Also the ions produced by it cannot reach very far (maybe a meter or so) before they loose their charge.

Also the charge from those ions is very small, much smaller than the amount of charge involved in an ESD event. I cannot imagine that the charged ions from the air can in any way cause damage to any electrical component.

So realize that the "zap" you got is not related to the ions from the air purifier.

An experiment has proven that the "zap" is related to the ions from the air purifier. Obviously, the plate is not grounded and close to the ionizer.

That ESD discharge is dangerous to unprotected devices so use proper ESD protection before touching any unprotected PCB and/or devices.

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  • \$\begingroup\$ I'm pretty sure the zap I felt are from the plate get highly charged by the ionizer since it's pretty close to the ionizer (less than a meter), after the first zap I waited for 1 minute and get a zap again from the same plate... (keep holding the plate does not result in any extra shock). So the conclusion here is "air ionizer is safe if it's far away from electronics"? \$\endgroup\$ – minhng99 Feb 8 '18 at 9:58
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    \$\begingroup\$ Now do the experiment again but switch off the ionizer. \$\endgroup\$ – Bimpelrekkie Feb 8 '18 at 11:10
  • \$\begingroup\$ nothing happen, the metal plate didn't get charged even for hours untouched, I used a neon bulb screw driver tester and get a glow on the bulb when I turn the ionizer on and touch the plate \$\endgroup\$ – minhng99 Feb 8 '18 at 13:31
  • \$\begingroup\$ OK, then that proves that the ions find their way to the metal plate and charge it. Now ground the metal plate to ground, switch on the ionizer and try again. For safety reasons you might need to ground the metal plate via a 1 Mohm resistor. Similar to how ESD wristwraps should be grounded. \$\endgroup\$ – Bimpelrekkie Feb 8 '18 at 13:54
  • \$\begingroup\$ Did not tried but I know the metal plate will be the same voltage as my body so no discharge would happen when I touch it, pretty much the same as me holding the metal plate, it will gradually get discharged to ground. \$\endgroup\$ – minhng99 Feb 8 '18 at 14:03

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