Grounding of Dust collector?????

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stonepecker

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I was thinking the other night and somethiing pop up that I didn't have an answer for. So here I am asking the membership.

Having talk to a couple of people and thinking this through, I am confused.

IF you use PVC pipe to connect your equipment to the dust collector system, (Whatever one you may have) how does the PVC pipe hold a static charge? I know that the collector is grounded throught the wiring of the motor. But it there is a danger from sparking within the system.......how do you ground it out?
And why would there be any static charge with the Plastic PVC piping?:confused:

Thanks everyone for your (their) help.
 
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Dust moving through the pvc piping and rubbing the walls will build up static charge. The danger, as I understand it, is enough of a charge building up and the right dust / air ratio creating the conditions for an explosion.

I don't know how to ground plastic pipe. If you use metal ductwork, problem solved. You system might even work a lot better with real ductwork instead of pvc pipe.

I don't know anywhere near enough to solve your problem, or how significant the danger is in a home shop. If you don't get answers from someone more knowledgeable here, you might consider looking on other forums. AAW might be a good choice. I wouldn't just ignore the issue and hope for the best.
 
I will NOT ignore this issue..... I haven't even begun to lay out any type of collection pipe.....but I have ideas and right now still trying to solve the problems I see.
 
I have read two methods for grounding plastic dust collection tubing, this includes the commercial ducting. Use a bare copper wire and run it on the inside of the tubing or wrap it around the outside of the tubing and connect the end to the metal housing of the motor or a ground rod.
Plastic builds up a static charge and can either explode or catch fire inside the tubing undetected until it's too late.
I hope that is helpful.
 
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Explosions with PVC ducting are a myth. For more information on this as well as "grounding" the PVC, take a look at this article. There are many more out there too. https://home.comcast.net/~rodec/woodworking/articles/DC_myths.html#who

I have a very extensive PVC ducting system with every tool connected. I have 6" and 4" with a high CFM cyclone system. None of my ducting is "grounded" and I have never even experienced a static shock. Again, read the article linked and it will provide much more info.
 
Scenario: Shopsmith bandsaw, Shopsmith dust collector. When using that combination, when my gut contacted the metal table of the bandsaw, I did receive a static discharge shock, (multiple times). Sorta takes you by surprise. To alleviate the problem, I did ground the hose from the dust collector to the metal of the dust collector and back to the metal grounded outlet box. No problems after that.
Not an expert as to whether that could possibly trigger a bigger problem.

Woodcraft dust collector grounding kit -- Buy Dust Collection System Grounding Kit at Woodcraft.com

Bob
 
I am an electrician.. and have researched a LOT about dust collection piping. I TOTALLY agree that the risk of fire or explosion is basically non existent in most applications. As an electrician, I have done a lot of work in "Hazardous Locations" and home dust collections systems do not qualify. There is actually a section in the National Electrical Code dealing with hazardous dust. The standards are clarified pretty well with concentrations and what hazard actually exists. I am not worried about fire or explosion at all.

That said, I still worry about static building up. Is it dangerous? Probably in MOST cases it is not. But could it lead to an uncomfortable shock? I believe so. What happens if that shock happens when my finger is close to a saw blade, or bandsaw blade, or causes me to push my lathe chisel in and causes a catch? All of those things are real to me.

What happens if I happen to have a pacemaker (which I do not), is it worth the risk of disturbing that? Not for me.

So I use metal piping when I did my installation. If I was using PVC, I would simply run a bare #14 the full length of the pipe and make sure it is grounded.

Overkill? Maybe, but worth it to me. Literally adds maybe 15 cents a foot to the cost of the PVC. Maybe makes it more complicated to install. Worth it to me.
 
I have a bare copper wire, runs through all my 4" piping. Even if there's near zero risk for static explosion, the removal of static electricity helps plastic not stick to the inside of the pipe. My wire hooks to a ground in a 120v outlet.

The real thing to watch for is sparks off your saw. Cutting super hard wood with heavy silica content can send sparks off saw blade and/or smoldering shavings into your bag. Also if you hit metal can launch a spark into the bag. Then it can sit in bag and smolder for hours before it ignites and burns your shop down. So if you see physical spark or have burning cuts then you should empty and dispose of contents in the bag.
 
Another way to ground a PVC system is to run wire from the tool, along the outside of the ducting, bare a short distance, loop and screw in a tek screw or similar, about a metre/yard/3 feet apart, the ends of the wire are then fitted to the DC and the machine from where the ducting started. If you have several machines, run a wire from each to join up to the main wire.
I've been told that a static shock can upset a pacemaker, as can a metal detector, used to find nails etc. in wood.
Kryn
 
wyone said:
I am an electrician.. and have researched a LOT about dust collection piping. I TOTALLY agree that the risk of fire or explosion is basically non existent in most applications. As an electrician, I have done a lot of work in "Hazardous Locations" and home dust collections systems do not qualify. There is actually a section in the National Electrical Code dealing with hazardous dust. The standards are clarified pretty well with concentrations and what hazard actually exists. I am not worried about fire or explosion at all.

That said, I still worry about static building up. Is it dangerous? Probably in MOST cases it is not. But could it lead to an uncomfortable shock? I believe so. What happens if that shock happens when my finger is close to a saw blade, or bandsaw blade, or causes me to push my lathe chisel in and causes a catch? All of those things are real to me.

What happens if I happen to have a pacemaker (which I do not), is it worth the risk of disturbing that? Not for me.

So I use metal piping when I did my installation. If I was using PVC, I would simply run a bare #14 the full length of the pipe and make sure it is grounded.

Overkill? Maybe, but worth it to me. Literally adds maybe 15 cents a foot to the cost of the PVC. Maybe makes it more complicated to install. Worth it to me.
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Mitch is correct. The danger of a home shop explosion is very very small. It depends on the ratio of dust to air. Also the danger of you being harmed in any way, other than the feeling of the shock itself, is almost nill. Not to say it doesn't hurt, but for most people it doesn't harm you. Exceptions would be people with electricaly implanted devices. I have personaly seen demos of people taking over a million volts of static electricity through their bodys with no harm. Girls with hair 2 feet long having it stand straight up on their heads. Sparks shooting out of their finger tips with no burns. I have also, while working in the papermill, taken a four foot flourecent bulb and held one end near a spinning roll of paper and the other touching a metal rail and lit the light. It takes about 530 volts to excite this bulb into lighting. The danger in static discharges are, as Mitch pointed out, where your body parts are when you get the shock and the reaction that follows when that happens.
When working on many expensive machines in the mill, we ofter would attach grounding straps to our wrists to avoid any damage to the electrical components from static discharge. This is the second danger in the home shop. Static dischare, if not properly grounded, can raise hell with chips and electrical circuits in the modern day tools. To ground your system from the outside, drill and install sheetmetal screws about every 6 feet. Make sure they are long enough to poke inside the pipe and still hold a copper grounding wire wrapped around it on the outside. Connect the end of the wire to any tool that has a 3 prong plug, water line, or metal piping. This is much easier than running a wire on the inside of the pipe, and if you want to add another machine, just tie into the system with another wire. Jim S
 
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As it has been brought up before i have stated my opinion on this and I agree an ounce of protection is worth it my opinion. Grounding takes so little time and effort because our systems are so small. Sparks from cutting as Jeff mentioned and also sparks from metal hitting the blades on the dust collector. Most makers have addressed the blade problem. Those are things to watch for as well. Drilling metal on lathes and sucking it in the dust collector can present a problem also. We all know how hot those acrylic shavings and metal shavings can get when we are drilling. These things do not get mentioned enough as to being a hazard. We talk about dust with dust collectors but other hazards exist. Be careful.

As far as the static goes the dryer humidity in the shop the chance of static are increased. This topic gets debated all the time and I do not care how many articles there are I would never tell anyone not to ground their equipment. If you do a google search there are numerous articles that can show you how to ground a dc system. I am not fond of running a ground through the pipe because it adds for catch all spots within the pipe. i am in favor of wrapping the outside.

There are so many things to consider if you want an efficient dc system. I will find that link again that I had posted not long ago here.

By the way it is not the voltage that will kill you but the amperage and there are many factors that go into that. No need to go there.

Here is an excellent article.

Dust Collection Research - Ducting


Here is the thread that started the conversation

My New Table Saw SUCKS!!! (
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A bigger concern is be sure you do not grind or have attached to the same system any thing you grind metal with, like your sharpening system for your tools. Hot metal and wood dust don't play well together.
 
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wyone said:
That said, I still worry about static building up. Is it dangerous? Probably in MOST cases it is not. But could it lead to an uncomfortable shock? I believe so. What happens if that shock happens when my finger is close to a saw blade, or bandsaw blade, or causes me to push my lathe chisel in and causes a catch? All of those things are real to me.
Click to expand...

When I left TWA in 1976, I went to work for a moving company that had an airfreight division... we had a back office that had a nylon carpet on the floor... walking around on that carpet usually built up a static charge and I would get zapped every time I opened a file cabinet... when the airline salesmen would call, I shuffled my feet to get a good charge built up then shook hands... always got a jolt.:eek:.. funny thing was, on their second visit the salesmen rarely offered to shake hands. :rolleyes:
To this day, I still tend to slap a metal file cabinet before I grab the drawer handle. :biggrin:

Don't know about dust charges, but nylon carpet will cause a visible spark.
 
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