Significant Static Discharge with 100% Festool "Path"

[Rockne]

Yesterday, I was working with my new Festool 150/3 sander on a MFT/3.  The Sander was plugged directly into an (also fairly new and very, very lightly used 15-20 minutes, tops) CT26 for both power and dust collection.  The CT26 had the factory hose.  I was getting VERY significant and continuous static discharge.  I tested the outlet and it was grounded correctly.  I am not (and have never) used any "cyclones" in the path.  My questions are three:  1) Is it one or more tool defects, 2) how do I get it to stop, and 3) has it damaged any of the tools. 

I have read the other forum threads on this topic, but none of them were exactly on point.  Many thanks in advance.

 

[FastEasySmartTOOL]

I've had static issues in the past if the 50mm end of the antistatic hose (connection to the CT) isn't snug. Possibly worth a try pushing the hose in a little further to ensure the conductive plastic is making a good connection.

 

[tbellemare]

I tested the outlet and it was grounded correctly.

Was the neutral the same potential as the ground? By that, I mean zero volts between them. The neutral is the longer slot on the left if the ground is on the bottom of the three.

Tom

 

[Rick Christopherson]

For some reason this topic has been coming up more this winter than I have seen in the past. I've commented on this a few times but it seems to get overshadowed among the false diagnostic postings.

Everything is working exactly as it should. It is the Human that is ungrounded and causing a nuisance shock. The human is experiencing an elevated static voltage, and then discharging to the tool/hose/vac, which is grounded.

These diagnostic postings suggesting to make sure everything is grounded are actually confusing the issue, because if the vac was NOT grounded, you wouldn't be getting the nuisance shocks. Everything would be at the same elevated static voltage as the operator, and there would be no discharge.  (well eventually there would still be a discharge, but it would be less often, but very large.)

 

[Rockne]

Everything is working exactly as it should. It is the Human that is ungrounded and causing a nuisance shock. The human is experiencing an elevated static voltage, and then discharging to the tool/hose/vac, which is grounded.

I'm not disagreeing with you, but could you explain why I (the human), without moving an inch am developing the static charge?  I am not exaggerating when I say that there is a significant discharge within just a few seconds of the previous discharge.  I didn't to a timed test, but 5-10 seconds was about the time between "touches" to the hose.  Again, I'm not disagreeing with you, but I find it curious that I could be developing such a huge charge without moving.  It wasn't particulalry arid in my neck of the woods yesterday either.  Looking forward to learning more. . . .

 

[erock]

Maybe Festool should sell this......

[attachimg=2]

[tongue]

 

[Rick Christopherson]

You don't need to be moving to experience the static charge. The air is moving, and this is what creates the static generator. The vacuum is drawing charge away from your workpiece from the moving air and fine dust particles. The finer the dust the more charge that gets created.

This charge is drawn away from the workpiece, but that results in the workpiece to have an opposing charge. You are taking on some of that charge in your body by touching it or simply being near the workpiece. As you get close to the grounded parts of the vac system, some of this excess charge discharges into the grounded system.

 

[tjbnwi]

I have a couple of these I use for other work. This was the first year I've had any discharge issues using my Festools. The wrist band clipped to the back of the hose cuff eliminated the problem.

http://www.amazon.com/Belkin-Anti-Static-Wrist-Adjustable-Grounding/dp/B00004Z5D1

Tom

 

[Rockne]

You are taking on some of that charge in your body by touching it or simply being near the workpiece. As you get close to the grounded parts of the vac system, some of this excess charge discharges into the grounded system.

O.k. that seems logical.  If that's accurate, then anything I touch that is grounded should result in the same discharge, right?  Thanks again for the education.

 

[JeromeM]

So the long and short is that the festool grounding is working perfectly.

 

[Greg M]

Everything is working exactly as it should. It is the Human that is ungrounded and causing a nuisance shock. The human is experiencing an elevated static voltage, and then discharging to the tool/hose/vac, which is grounded.

I disagree with this since the only place that I've had a strong (some VERY strong) static shock this winter is when using the track saw.  I've had a couple of minor ones when handling my dust collection hoses but nothing even close to using the tack saw.  By your explanation I should also get strongly shocked by touching my properly grounded table saw, bandsaw and anything else that's grounded metal.  Not just the track saw.

Now I agree that during low humidity we will most likely be the source of the static shocks we receive.  However, there is something about the track saw that is producing very strong static discharge. 

There is something wrong but the problem is intermittent. 

Festool's official position (deduced from talking to Festool service) at the moment is that different material will produce different levels of static and that the materials that are producing higher static exceed the ability of the system to discharge that static.

Human is part of the equation but the tack saw is the problem.

 

[Bohdan]

The air being sucked thru the track saw is causing the static build up in the human because the earth path thru the hose is not connected to the handle of the saw and when you approach the earthed, thru the hose, part of the saw you get a discharge.

IMO this is a design fault that would be easily remedied by having the saw handle made of conductive plastic and earthed to the hose as the saw doesn't have an earth wire.

This of course would only work if an antistatic hose is being used.

 

[Rick Christopherson]

By your explanation I should also get strongly shocked by touching my properly grounded table saw, bandsaw and anything else that's grounded metal.  Not just the track saw.

And for all of your examples, the workpiece is grounded by resting on the cast iron table. They also don't have the same velocity in the dust extraction stream. So no, they are not the same.

 

[Rick Christopherson]

IMO this is a design fault that would be easily remedied by having the saw handle made of conductive plastic and earthed to the hose as the saw doesn't have an earth wire.

You can't put a conductive handle on a power tool. Instead of discomfort from a little static, you'd get people dying from cutting hidden wires and the like.

 

[Greg M]

By your explanation I should also get strongly shocked by touching my properly grounded table saw, bandsaw and anything else that's grounded metal.  Not just the track saw.

And for all of your examples, the workpiece is grounded by resting on the cast iron table. They also don't have the same velocity in the dust extraction stream. So no, they are not the same.

Ok then, not that I agree with you, but I'll change my examples to my router, domino, planer, sanders, Kapex and any other Festool tools that use the same CT, AS hose and the same airflow (except the sanders).  None of those are producing static charges.  I don't recall even 1 static shock from those.  However, under the same conditions with the same type of material I can get very strong shocks from the track saw.  My track saw doesn't seem to shock as often as others do but when it does it can be strong.

 

[Greg M]

BTW, I'm not trying to argue with Rick.  It's just that when only one position keeps getting repeated without any rebuttal it can be interpreted that everyone is in agreement with that position.  My responses to Rick are simply giving a different point of view.  I believe that there is a problem with the track saw but it's difficult to track down because the problem is intermittent.  I don't think that it's a safety problem but it is a serious nuisance that can be very uncomfortable at times.

 

[Bohdan]

Static build up is produced by a continuous fast flow of a large number of particles such as in a saw cut or while sanding. Routers,
dominos, planers etc. produce large particles often for a short time and so tend not to build up to high discharge voltages.

I have been zapped while sanding or vacuuming up sand when using a non AS hose.

The atmospheric conditions must also be right and that is why it appears so intermittent.

You can't put a conductive handle on a power tool. Instead of discomfort from a little static, you'd get people dying from cutting hidden wires and the like.

This would not happen if the saw was properly earthed like they used to be before they were made of plastic.

 

[Rick Christopherson]

You can't put a conductive handle on a power tool. Instead of discomfort from a little static, you'd get people dying from cutting hidden wires and the like.

This would not happen if the saw was properly earthed like they used to be before they were made of plastic.

It doesn't matter whether the tool is double insulated or grounded with a 3-prong plug; you cannot have conductive handles on the tool that are electrically connected to other parts (such as the blade housing where the vac connects).

UL 60745-1: Hand-Held Motor-Operated Electric Tools--Safety--Part 1: General Requirements

Section 21.32
For all tools that are likely to cut into concealed wiring or their own cord, handles and grasping
surfaces, as specified in the instruction manual, shall be formed of insulating material or, when of metal,
shall be either adequately covered by insulating material or their accessible parts shall be separated by
insulating barrier(s) from accessible metal parts that may become live by the output shaft. These
insulating barriers are not to be regarded as basic, supplementary or reinforced insulation.

 

[frodo]

Rockne,

I have been getting the same type of shock using the track saw and also intermittently. Very annoying. Tim listed a possible solution. Are there any others??