Spraying wooden floor with water to reduce ESD damage ? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: July 20, 2022, 08:38:33 pm
content: Hi,Now assembling 2kW Offline PSU.....have ESD mats on tables, and wrist straps and each mat is earthed via 1MEG.Floor is wood, (my shoes are ESD shoes and dont give me a static shock when i touch the metal bannisters in the British Library)Do you think spraying it lightly with water will help reduce potential ESD problems.....eg with one of those flower leak sprayer things.The room is in the attic, and is always very hot, so the water will in some way be evaporated and be in the room air too.

author: metrologist
author_rank: Super Contributor
timestamp: July 20, 2022, 08:44:34 pm
content: We've humidified the air and apply ESD protective floor mats/tiles.

author: IconicPCB
author_rank: Super Contributor
timestamp: July 20, 2022, 09:55:20 pm
content: Consider adding fabric softener to the water.

author: Bud
author_rank: Super Contributor
timestamp: July 21, 2022, 05:26:24 am
content: Spraying water around while working on a 2kW switching PSU sounds a bad idea to me.

author: Gyro
author_rank: Super Contributor
timestamp: July 21, 2022, 08:25:09 am
content: I'm sure the London fire brigade would welcome anything that reduces the flamability of your work area under the current circumstances.

author: jpanhalt
author_rank: Super Contributor
timestamp: July 21, 2022, 08:32:20 am
content: Have you considered whether the renter below you wants a wet ceiling? Electrical wiring under the floor? Whether the landlord wants you to warp and damage his floor and/or create a black mold incubator in whatever is between floors?

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 21, 2022, 09:24:21 am
content: Making a wooden floor a little bit wet with a plant sprayer will not help because it won't decrease the resistance to earth. Only when the floor is soaked with salt water and there is a proper ground connection to the real ground will it reduce possible ESD.But this is not something you should do on a floor that is not your own or above someone else's property.Using a humidifier to increase the humidity of the air can help. Risk of ESD is greater when the relative humidity is say 30% compared to 70%.Also your clothing is of importance here. Woolly fabrics tend to build up more static charge.To be safe you should check the grounding of your outlets and connect your ESD mat to it too.

author: Kleinstein
author_rank: Super Contributor
timestamp: July 21, 2022, 09:48:49 am
content: For wood a little bit more humid (even below the level where the color changes) already makes a difference. It would not reach the 1 M ohms typical resistance used with mats and straps, but it is still not bad and usually no danger of charge build up on wood.Higher humidy in the air in general can help. If possible avoid RH < 50%.

author: Feynman
author_rank: Regular Contributor
timestamp: July 21, 2022, 07:09:51 pm
content: Spraying the wooden floor is kind of pointless. By walking on a wooden floor chances are you don't build up much charge no matter how the wood is connected to earth. Luckily, wood just isn't a good charge donator. By wearing a wrist strap you are grounded anyway. A floor with a certain conductivity to earth is only needed if you are operating with ESD sensitive devices while standing, i. e. not wearing a wrist strap. In this case, the potential equalization takes place via your (ESD-)shoes instead of a wrist strap.But humidifying the air certainly does help. Dry air (RH <20%) is a real nightmare from an ESD point of view. But you don't have to worry much about humidity levels above ~40%.Just keep it to the basics: Keep your ESD sensitive devices as long as possible in shielding packaging and ground yourself with the wrist strap before touching any ESD sensitive devices.ESD safe cloths are a good idea, too. If you don't have special ESD cloths cotton wool should be fine. Just watch out for the synthetic stuff.

author: tooki
author_rank: Super Contributor
timestamp: July 25, 2022, 10:44:18 am
content: Just get a damned ESD floor mat.