Static Electricity and the Oneida Ultimate Dust Deputy

Some Festool vacuum owners had issues with the original Ultimate Dust Deputy (UDD), apparently because it caused a static build up that discharged through the vac damaging its motherboard in the process.  Do you need to be concerned about the same thing happening to your vac?

You can read Oneida’s official description of the issue and how they corrected it here (also note the comment about Festool’s warranty):
What Oneida say is:
The inlet of Festool® dust extractors incorporates a connection to the earth ground to provide a safe discharge pathway for static electricity that may be generated when wood dust moves through hose or plastic parts. This grounded inlet works in conjunction with anti-static hoses. Oneida wants to make certain that our Ultimate Dust Deputy® customers understand that there is a grounding pathway that must be maintained.

Oneida has always used static dissipating components in the Ultimate Dust Deputy® but to make absolutely certain that this path to ground is maintained at the highest level the UDD uses static conductive components. “
What does this all mean?  And what does it mean for those of us with cheaper vacs that do not have a grounded inlet1?the first thing is to understand the jargon, and there is a helpful summary on Oneida’s site:

http://www.oneida-air.com/static.asp?htmltemplate=static/static-resistance-faq.html

And this diagram in particular:

Static Resistance Ranges

.. which shows a scale for the relative conductivity of materials, from insulators at the top to conductors at the bottom.

Dissipative materials allow charges to flow but do so more slowly than conductive materials.    The conductive materials in the new model allow any static  to discharge via the grounded inlet in the festool (which is in turn is connected to the earth for your domestic wiring, via the plug):

What was going wrong with the old model?

My theory is that the static created by the large amount of contact between spinning wood dust and the plastic cyclone  (see previous post for an explanation) caused a charge to build up in the cyclone that the materials in the original UDD could not dissipate quickly enough, and this allowed a large potential voltage to accumulate.

Ultimately, any static accumulating that is not dissipated through the air will have to go somewhere and it is possible that the voltage – if it reached high enough level – might  travel across the air in the outlet hose (which will have been slightly conductive due to the dust particles travelling through it) and into the electronics of the vac.

If this is correct, then in theory the same thing could happen in my set-up since the vac inlet is not earthed and there s no way for the the static to drain other than through the air, through the operator (me) or through the vac.

I suppose the fact the new model  is made of  conductive materials reduces the risk of a large discharge since  any charge will be distributed over the surface area of the UDD and the hoses, creating more opportunities for the charge to dissipate to air, but nonetheless I plan to follow Oneida’s guidance and find an alternative way to ground the UDD.

Is static electricity likely to damage my vac, even if I do not use a cyclone?

Festool do not appear to think so – they sell vacuums with either ‘antistatic’ or normal hoses (the antistatic hoses have a high carbon content) Here is what they say about the antistatic versions:
“Festool’s Antistatic hose design helps you work cleaner by preventing dust from accumulating on the exterior of the hose. It helps you work more safely by preventing static discharge or shocks. And you’ll work more efficiently with a system that prevents clogging due to particulate buildup inside the hose”

There is no mention of protecting the vac from damage, and the fact they supply non-antistatic for use with their vacuums suggests the static generated by a normal vacuum is nothing more than a nuisance.

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1 If it is grounded there will be a small metal tab in the inlet where your hose connects to the vac

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