CT Antistatic Hose Confusion

[jbasen]

I'll state up front that I own an Oneida Ultimate Dust Deputy (UDD) and have ever since I bought my CT Mini a number of years ago.  I went through all the issues between Festool and Oneida with the UDD not maintaining a clean electrical path between the tool and the vacuum that resulted in Oneida coming out with an updated cyclone made out of conductive plastic and several other enhancements that improved the conductivity of the UDD. 

Personally this all made me very careful to make sure that I have a clean electrical path but, I've never tried to measure it; until now.  On my cheap Ridgid shop vac I notice that after vacuuming for a while there is sawdust sticking to the vacuum hose and that has become my indicator that there is a static charge building up from the flow of air through the hose.  I've never noticed this on the Festool vac but curiosity got the better of me this evening and I pulled out my trusty multimeter and started measuring the conductivity (resistance) of the hose and fittings between the tool and the vacuum. 

What I found surprised me.  The Festool hose absolutely showed it was conductive as did the cyclone and all the UDD parts from Oneida.  However, the Festool hose fittings, even though they were marked AS, did not show any conductivity.  [eek] Clearly there can't be a complete electrical path from the tool to the vacuum if the hose fittings aren't made of conductive plastic.  [huh]

I'd greatly appreciate it if someone could educate me on this as I'm very confused; especially after all the fuss that was made over the UDD not being conductive a few years ago and the potential damage to a Festool vac if a clean electrical path from tool to vac is not maintained.

Thanks in advance

 

[rdr]

Resurrecting this through a search for the same answer

I mentioned on a couple of threads recently that I want to extend my AS hose for my Midi. I'm keen on keeping the anti static qualities which I presumed would involve making sure there is a conductive path back to the machine but on testing my AS (green) hose and fittings with a continuity meter I cannot pick up any conductivity anywhere.

Can anyone confirm if the AS hose or fittings are definitley electrically conductive?

Are they the opposite and specifically non-conductive to guarantee charge can't build up in the hose and flash back to the machine?

 

[ben_r_]

I can confirm no part of the exterior of the Festool AS hose conducts electricity. Or at least enough to prove continuity with a DMM.

[attachimg=1]

[attachimg=2]

[attachimg=3]

[attachimg=4]

And one to prove my DMM can in fact test for continuity :

[attachimg=5]

 

[rdr]

Thanks same as me then. I tried inside the hose fitting too just to make sure and couldn't pick up any conductivity.

Does this mean the antistatic principle of Festool hose system is NOT to conduct back to the machine? Many of the threads on here seem to indicate continuity must be maintained back to the machine which is whats confusing me.

Apologies if I am missing something

 

[ben_r_]

Appears the conductive properties are in the plastic of the hose: LINK See post #4.

Could be that a continuity tester isnt using a high enough voltage to achieve conductance. Harmful static electricity is usually a very high voltage and low amperage.

 

[Holmz]

Same results with a different model DVM left me scratching my chin too.

 

[Bohdan]

You cannot read the conductivity of an antistatic hose with a DVM. You need to use a Megger which is a device that uses a high voltage to read continuity and is used to test for high voltage leakage in insulating materials.

The festool hose and fittings have a significantly high resistance which at low voltages appears infinite and doesn't show on a DVM.

 

[ben_r_]

You cannot read the conductivity of an antistatic hose with a DVM. You need to use a Megger which is a device that uses a high voltage to read continuity and is used to test for high voltage leakage in insulating materials.

The festool hose and fittings have a significantly high resistance which at low voltages appears infinite and doesn't show on a DVM.

Thats what I was thinking. The anti-static properties are within the material of the hose and only conductive of high voltages. Thanks for confirming how that works.

 

[rdr]

Thanks for all the replies, this makes sense and also makes the extending of my hose project much more straight forward again.

I'm building a boom arm that will carry extraction, air and power. The power will be both a plugit extension run back to the Midi but also a domestic supply for other tool applications. The boom will be made from steel and earthed, the hose integrated into it will not be anti static (because I have it handy) so I will use the boom earth to deal with static up until the connection where the AS hose joins leading to the Midi.

With the AS hose being closest to the Midi my thinking is it will remain protected.

 

[ben_r_]

Thanks for all the replies, this makes sense and also makes the extending of my hose project much more straight forward again.

I'm building a boom arm that will carry extraction, air and power. The power will be both a plugit extension run back to the Midi but also a domestic supply for other tool applications. The boom will be made from steel and earthed, the hose integrated into it will not be anti static (because I have it handy) so I will use the boom earth to deal with static up until the connection where the AS hose joins leading to the Midi.

With the AS hose being closest to the Midi my thinking is it will remain protected.

Sounds cool. Make a new thread and post some pics when youre done!

 

[PeterK]

For remodeling type work I use the Festool 27mm long non-AS hose with my Midi. Never had any issues doing that. Can only see shock potential from larger chips possibly. I don't understand the comment that a non-AS hose can cause damage to the vac as Festool specifically sells non- AS components to use.

 

[AIPDX]

Some of the statements above are physically incorrect. Resistivity of a hose has nothing to do with voltage. However, you do not want your vacuum hose to be a grounded conductor which puts you at risk of electrocution. You want to have high resistivity, as high as possible, but allowing static electricity to dissipate. A typical resistivity of antistatic hose is around 10 to the power of 8 to 10 to the power of 9 Ohm (i.e., up to a gigaOhm). You need a fairly sophisticated ohm-meter to measure resistivity in the range from 100 megaOhm to a GigaOhm. However, this high res is sufficient for static electricity to dissipate.

Anything with res lower than about 10 kOhm is called conductive, not anti-static.

 

[ben_r_]

Some of the statements above are physically incorrect. Resistivity of a hose has nothing to do with voltage. However, you do not want your vacuum hose to be a grounded conductor which puts you at risk of electrocution. You want to have high resistivity, as high as possible, but allowing static electricity to dissipate. A typical resistivity of antistatic hose is around 10 to the 8th to 10 to the 9th Ohm. You need a fairly sophisticated ohm-meter to measure resistivity in the range from 100 megaOhm to a GigaOhm. However, this high res is sufficient for static electricity to dissipate.

Anything with res lower than about 10 kOhm is called conductive, not anti-static.

Hmmm, not sure that jives with that a Festool employee wrote about it:

[attachimg=1]

What are your thoughts on that?

 

[Bohdan]

Hmmm, not sure that jives with that a Festool employee wrote about it:

[attachimg=1]

What are your thoughts on that?

I think that statement is no way contradicts what [member=28086]AIPDX[/member] said.

They are both absolutely correct.