back in 2019 i made a video explaining why i believe it is a myth that the dust inside the pvc ductwork of a non-industrial woodworking shop can be ignited by static electricity and cause a fire or an explosion i backed up my opinion with a paper written by an mit scientist who is way smarter than all the folks arguing about it on the internet if you're interested in that debate i'll link to my video and to the paper below but the fact is some people simply want to ground their pvc ductwork and it's not my job to force my opinions upon you my job is to make your shop time more enjoyable and if grounding your ductwork makes your shop time more enjoyable i think you should do it especially if you occasionally get a little shock off your ductwork that may distract you while you're using a dangerous machine that wouldn't be good so in this video i'm going to show you how to ground a pvc dust collection system properly including answering some of the most common questions people have such as how to address flex hose or whether to run the wire inside or outside the duct work and how to get that charge from the pipes and hoses into the physical ground by the way some of this footage was filmed back when i was healing from a hand injury so if you're wondering about the splint don't worry i didn't get hurt now let's get started as air and sawdust flow through your hoses and your ducts it generates static electricity that static charge can build up and give you a shock when you touch a pipe or a hose or sometimes even a machine a shock from a pvc duct work or a long flex hose isn't likely to be painful but it can be dangerous if it distracts you at the wrong time the reason why pvc is unlikely to deliver much of a shock is because it's an insulator that means very little of the static that builds up inside the duct will transfer through the walls to the outside where you may touch it and go into your body that doesn't mean there will be no charge on the outside of a pvc duct you need only run your hand over the surface of the pipe after running dust through your system for a few minutes to feel the charge on the outer surface the idea then is to give that static charge a direct route from the pipe to the ground so it won't build up this is done by running wire through the whole system it doesn't have to be heavy duty wire i use 18 gauge bare copper wire because it's inexpensive yet durable enough for the job i'll link to the stuff that i use which is fairly inexpensive as i said below this video if you need some among the many endless debates involving dust collection systems is whether you should run your ground wire inside the pipe or outside the pipe as i said pvc is an insulator the bulk of the charge will be contained inside the pipe where it can't reach you on the outside but some of it clearly does migrate through the system and end up where you can touch it so we want to dissipate that interior charge as much as we can the problem is it's difficult to run that wire inside a duct without creating all sorts of places for chips to get caught and eventually turn into obstructions i did once read a clever idea about using strips of foil tape inside the duct but it's very difficult to stick this stuff flat inside a long length of pipe if you want to explore it further i'll link to the reference where i got that idea i prefer to bore holes and then drive three quarter inch long screws into the pipe every one or two feet alternate from one side of the pipe to the other all the way down its length then i wrap my wire around the head of each screw running down through the pipe there's no need to spiral the wire all the way around the pipe just zigzag from one side to the other if your wire isn't long enough to run the entire length of the system just start a new piece on the same screw head where the last piece ended as long as the screws only protrude into the interior of the pipe a small amount they shouldn't catch any debris and as long as your pilot holes aren't too large the screw should tighten well into them and plug any potential leaks each screw will then act like a little lightning rod to capture the charge both inside and outside the pipe and channel it through your copper wire and out of the system flex hose is really easy to ground because it generally has a wire integrated inside so you simply expose the end and then you connect your copper wire to that if your flex hose doesn't have an integrated wire like the inexpensive stuff that just has a plastic set of ribs you're going to have to wrap a copper wire all the way around the outside and to keep that from coming loose and catching you're probably going to need to go between each rib and it's not going to be worth it honestly if you want to ground your system you should get flex hose that has an integrated wire all of my blast gates are acrylic and there's no need for me to ground them but if you have metal blast gates you should connect your grounding wire to them as well so you don't get a shock from them so now you have a copper wire running from where your flex hose attaches to your machine all the way through the ducts to your dust collector how do you get it to the ground well you don't have to physically drive a stake into the earth and connect your wire to it your dust collector is already grounded through the ac outlet in your wall so just connect the end of your wire to the metal body of the dust collector itself and you've tied everything together another option is to connect the other end of the wire that comes off your flex hose where it connects to the body of a machine such as your table saw and then wire it to the body of that i even saw this solution online plugging the end of the wire directly into an outlet but frankly i don't know why you would use such heavy gauge wire for this it's not necessary and who has an extra outlet in their shop anyway now that your system is grounded you can sleep better knowing you are much less likely to get a shock from it when you touch a duct but don't bother trying to argue with me about preventing an explosion we're running small woodworking shops not flower mills don't forget to check out the links below for more information and check this out we couldn't do what we do without folks like the bushy family over at clearview cyclones not only do they make the best dust collection cyclones on the market but their woodworkers supporting woodworkers they're the sponsor of this video and i really hope you'll thank them by visiting their website and using our discount code below this video
