pvc duct static discharge?

[Dan Hintz]

I give up... anyone who quotes Mythbusters as a truly scientific test (considering their tests are anything but scientific and have been proven wrong on multiple occasions) is not interested in science, they're only interested in pointing to someone who agrees with them.

I'm done.

[David Hostetler]

I give up... anyone who quotes Mythbusters as a truly scientific test (considering their tests are anything but scientific and have been proven wrong on multiple occasions) is not interested in science, they're only interested in pointing to someone who agrees with them.

I'm done.

Hey now, I hope you aren't fussing at me. I didn't say it was scientific fact, I said it was interesting....

I hadn't seen your previous posts, sorry short attention span due to

[John P. Smith]

I have noticed that I get static shocks from my Rigid shop vac using the hose that came with the vac.. That unit has a hose with no wire inside.When I use a 30' hose with wire inside this hose does not give off shocks which means the Static is bleeding though the plastic to the wire which is grounded.

Interesting... because I have gotten shocks from both types of hoses. My original hose appears to be all plastic, my replacement, more flexible, hose appears to have a wire inside, although I cannot see the end of it, and it is not grounded to anything. I am curious, how did you ground your vac hose?

I have always agreed with Yogi Berra... "In theory, theory and reality are the same, in reality they are not." These threads on static charge and bleeder resistors prove it. If something works, it works, and all the theories and even accepted facts and laws of physics and nature don't change that. It only means we mere mortals have not come up with a theory on everything!

[Lee Schierer]

When I first installed my DC system with pvc pipe I noticed a lot of static on the plastic pipe as it came home from teh store and as I cut various pieces to install it. It would raise the hairs on your arms from an inch or so away from the pipe. This lasted a few days until the pipe became a little dusty. Now, you can't even get a small fragment of tissue paper to stick to those same pipes. Don't waste your time with tape or wires, inside or out, rub the pipe with a handfull of sawdust from your ROS or just ignore it and the static will be gone in a few days or weeks depending upon how much you use the shop.

[Dan Friedrichs]

. If something works, it works, and all the theories and even accepted facts and laws of physics and nature don't change that. It only means we mere mortals have not come up with a theory on everything!

...or it means that people have convinced themselves that it works, even though the evidence may suggest otherwise. It's pretty hard to devise an objective test to determine whether or not wrapping a grounded wire around ductwork makes a difference or not. If you spend a few hours wrapping wire around things, you are going to be predisposed to BELIEVING that your efforts made some difference, whether or not they actually did.


People who are quick to deny established and proven theories are often the ones with the most tenuous understanding of them.

[Anthony Whitesell]

I can only speak for myself. I was going to be cheap and skip the "ground" wire until I after got the first few hits, then I installed one. All I know is that installing a bare wire instantly stopped the hits, presumably due to constantly discharging the static build-up. Do I know if the sawdust build up would have stopped it? No, I don't and I wasn't in the mood to wait to find out. The shocks hurt too much. Do I know if an insulated wire would have helped? No, as mine is bare.

So to a certain extent I agree with you. But I do refrain from commenting of the sawdust built option and the insulated wire option as I do not have any personal experience with either and my education didn't cover the effects of sawdust on the dissipation of a static charge.

[Phil Thien]

I thought one of the factors in static electricity charges was the amount of surface area.

So wouldn't winding a wire around the pipe essentially section the large plastic surface into many smaller ones, thereby limiting the potential for giant static charges?

[Ole Anderson]

I just sit back and chuckle at this whole static-no static thing with PVC pipe. Except for the flex hoses, which all have a steel wire for support, all of my ductwork up to the cyclone is steel with one piece of 7" alum flex. Ever see a commercial WW shop with PVC pipe?

[Anthony Whitesell]

Surface area is one factor and does work as you mention (ability to build larger charges) but it is a second order effect and not as much effective as the dielectric constant and resistivity. Based on the other factors, the charge builds as you move toward the center of the surface. So the larger the area the more charge can build at the center. Think of trying to build the tallest mountain you can on your property. If you use sand, the maountain cannot be very tall because the slope cannot be very steep (low constant, high conductivity, etc). If you use something sturdier like concrete then you can get the sides to be more vertical and build a taller mountain (ie., higher constants, better insulator, etc.).

[Harvey Pascoe]

Static shocks are caused by a difference in potential between your body and the source. For example I had horrendous shock problems with my buffing machine in winter and I was advised to electrically connect myself to the machine which I did and the shocks stopped. I've never gotten shocks from my PVC ducting.

It seems to me that if the PVC ducting is attached to the machine and you are touching the machine frequently, you should be equalizing the charge and shocks shouldn't happen. Because we wear shoes, we are usually not grounded. I can understand that different plastics, like ABS, might not transfer the charge to the machine. So would establishing electrical conductivity from duct to machine do the trick?

Its also my understanding that the charge is not INSIDE the PVC pipe but travels along the outside, the very same as copper wire. I have a very hard time buying the claim that the electrical charge can be at different levels at points in close proximity on the same pipe. Electricity always seeks a ground. Yes, a static charge will disperse over a wide area or long length and give you slightly different readings (assuming you could measure it) at a point 20 feet away, but it would be insignificant the same as for any length of wire. Maintain conductivity that equalizes potential and you won't have a problem with shocks.

[Aaron Rowland]

I give up... anyone who quotes Mythbusters as a truly scientific test (considering their tests are anything but scientific and have been proven wrong on multiple occasions) is not interested in science, they're only interested in pointing to someone who agrees with them.

I'm done.

Hmmm, I didn't see see any threads here that said Mythbusters was a truly scientific test . Nor did I see anyone who said the Baldor statement on bleeder resistors and motor starts were truly scientific and documented with tests. If fact I don't think I have every seen a truly scientific PhD paper here on anything. Most of what we work with is some ones opinion. If they have a good reputation as being correct most of the time most people will listen. If the person is wrong most of time most people will ignore the opinion. Baldor is a very respected motor company and I won't argue with their opinions but simply except their opinion as fact with the cravat it may or it depends.. Maybe Mythbusters does not have the strength that Baldor has but has a decent enough track record that I may except their conclusions as fact.No body has the time to test every opinion by a company or an individual as suspect unless they have a terrible track record. Then I just ignore what they say and look for another reputable source. Verification by reputation works for me but not verification by repeating the same wrong stuff over and over.

[Doug Palmer]

Static charge is related to humidity. My suggest is go buy a $40 humidifier and put it in your shop. Dust on the pipe will help, but the point of dust collection is to have a dust free shop, or at least as close as possible. I concur that wrap of copper wire will do little to no good, especially an insulated wire like the one shown in the earlier photo. I had to chuckle. Get the humidity up in your shop or install metal duct work.

[John P. Smith]

I can only speak for myself. I was going to be cheap and skip the "ground" wire until I after got the first few hits, then I installed one. All I know is that installing a bare wire instantly stopped the hits, presumably due to constantly discharging the static build-up.

Anthony, I am glad you think that wire stopped you from getting shocked. But that flies in the face of all theories and science of static electricity. You spent time wrapping that wire, so you were predisposed to believe it would stop the shocks... so it did!! Or, at least you think it did. Doesn't matter, just as long as you don't feel any more shocks, right? In fact (based on the laws of static charges, as presented on this and other forums) I believe you are still getting shocked, you just don't feel it, because you invested time and money in installing a "ground" wire believing it would stop the shocks. You are just the (fortunate) victim of the placebo effect. Mind over matter, all that.

Seriously, I still say, if it works, it works. I have read over and over, here and on other forums, that a bare or insulated wire, wrapped like you did yours, stops people from getting shocked. That is good enough for me, to the point that if I ever install any PVC dust collection duct work, and then I get zapped from it, I will try the wire wrapping to eliminate it. As far as I am concerned, I have seen enough posts saying that it works that it is not a "myth" to be busted.

[Phil Thien]

What are those of you getting shocks doing when you get a shock, operating a blast gate?

[Anthony Whitesell]

Anthony, I am glad you think that wire stopped you from getting shocked. But that flies in the face of all theories and science of static electricity. You spent time wrapping that wire, so you were predisposed to believe it would stop the shocks... so it did!! Or, at least you think it did. Doesn't matter, just as long as you don't feel any more shocks, right? In fact (based on the laws of static charges, as presented on this and other forums) I believe you are still getting shocked, you just don't feel it, because you invested time and money in installing a "ground" wire believing it would stop the shocks. You are just the (fortunate) victim of the placebo effect. Mind over matter, all that.

Quite an interesting approach but unfortunately not against the science or theories according to my textbooks. I have read many of the sites and even have one bookmarked. The primary effect of the ground wire is to provide a discharge path for the accumulated charge. If enough of the charge is dissipated then you don't get shocked. Or, like you mentioned, if I am I don't feel it.

Standard scientific principal says to change one variable at a time. The only thing I changed was adding the ground wire. Before the wire, shocks. After the wire, nothing. To be completely thorough, I should have removed it to see if the effect came back.

I am familiar with the misnomer of "grounding PVC" and have done quite a lot of refreshing myself on the theories of static electricity. For lack of a better description, there's miles difference between hole thery and static theory and hence the complaint that you "can't ground PVC". In terms of "grounding" it is true, but a path to ground can be provided to assist with providing a discharge path such that the charge cannot build enough to overcome the breakdown voltage of air. I've learned avoid the aspects I don't know of (ie., fire starting, the effects of insulated wire, effects of sawdust on static charge, etc). I'm not an expert but have much learned and first hand knowledge. I may be getting shocked and don't feel it, but the hairs don't stand up on my arm as I walk past either. So I know there more than predisposition or mind over matter.

I have found the following situation interesting as I have gotten more involved with the discussions on static electricity. In a previous job I tested ICs. The process started with a vibro-bowl, a bowl with a spiral shaped ID that shakes and is machined in such a way that the parts all align themselves in the same direction (really a quite cool piece of mechanical engineering). One key piece is the inside of the bowl is covered in a rubberized coating, that was not conductive, to pad the parts as they tumble around. As the IC packages are all insulators, as they move around the bowl and rub on each other, they build a static charge on their packages. The parts are so small (around 3x6mm), that if left unattended the parts will literally start to float in layers as the charge builds up. Again quite impressive to see an IC hovering 2" off the work surface . In the event this occurs, the procedure was to mist the parts with 1-2 sprays of isopropal alcohol. Alcohol was used instead of water because it it evaporated quickly. As soon as the mist hit the bowl the hovering parts would drop like a lead weight. In this case there was no path to ground, just the random charge provided by each alcohol droplet was enough to equalize the charge acculated on the ICs.