Grounding
- Thread starter Stacy12
- Start date
I live in a fairly dry region in California that should be bad for static buildup. More humid locations should not be able to build up nearly as much static charge.
I did nothing to ground my PVC pipe and have not seen any reason that I would need to. The only minor issue was a small zapping sound where the wire in a short piece of flex duct was sparking to the frame of my bandsaw. I exposed enough wire to bend it so it made direct contact and the problem went away.
Also, schedule 40 PVC is way heavier than needed for a dust collector. It is also much more expensive. Look for sewer and drain (S&D) pipe at a local irrigation supplier. It is much thinner, but more than strong enough for the low pressure requirements of a dust collector. Fittings are expensive. You may end up mail ordering them.
Steve
I did nothing to ground my PVC pipe and have not seen any reason that I would need to. The only minor issue was a small zapping sound where the wire in a short piece of flex duct was sparking to the frame of my bandsaw. I exposed enough wire to bend it so it made direct contact and the problem went away.
Also, schedule 40 PVC is way heavier than needed for a dust collector. It is also much more expensive. Look for sewer and drain (S&D) pipe at a local irrigation supplier. It is much thinner, but more than strong enough for the low pressure requirements of a dust collector. Fittings are expensive. You may end up mail ordering them.
Steve
Grounding
Stacy12,
PVC is an insulator and cannot be grounded. You do want to ground the wire inside any flex because that will pick up enough charge to give you a shock. Since most machines are grounded, connecting the wire to the machine is sufficient. Keep your shop humidified; that's the best thing you can do to reduce static. It's also better for your health. This area (static on PVC, dust, and explosions) is ridiculously overblown. I've never gotten a shock from mine even though it raises the hair on my arms so I know the charge is there. Dr. Rod Cole at MIT Lincoln lab (google his name) has written an article that debunks the hype.
bababrown
Stacy12,
PVC is an insulator and cannot be grounded. You do want to ground the wire inside any flex because that will pick up enough charge to give you a shock. Since most machines are grounded, connecting the wire to the machine is sufficient. Keep your shop humidified; that's the best thing you can do to reduce static. It's also better for your health. This area (static on PVC, dust, and explosions) is ridiculously overblown. I've never gotten a shock from mine even though it raises the hair on my arms so I know the charge is there. Dr. Rod Cole at MIT Lincoln lab (google his name) has written an article that debunks the hype.
bababrown
R and D Nikkel
New member
We were getting shocks, nasty ones, from the metal HVAC fitting we used to collect dust from the side grinder in our dirty room. We live in a very dry climate. All we did was put foil tape from there along the pipes, over every screw we practically could, and then put a wire between the the tape and the ground on our big band saw. Even though the collector we were getting shocked from was quite a way away and in another room (we put a wire through the wall with the foil tape stuck on both ends) it stopped the problem totally.
Shocks
Shocks
Finally got my system up and running this past weekend and made lots of saw dust
!
While running there was a definite "Static field" around my plastic S&D piping and collection barrel (my barrel is a plastic 55gal drum, cut down to approx 40gal and capped with a clear plastic lid - photo attached.), such that when I got within 3 to 4 inches of the piping or drum, the static would cause the hairs on my arm to stand up. Did not experience any significant shocks however.
Shortly after shutting down, I noticed a sparking sound that would repeat about every 20 seconds. Upon investigation, I discovered a spark jumping between the metal carrying handle of the collection barrel and the metal cage surround the exhaust filters (attached photo). Figuring the swirling of the dust in the plastic barrel was the cause of the static build-up, I grounded the metal handle; however, the 20 sec interval between sparks continued. Thus, the static was not being generated in the barrel, but in the filter stack. Indeed, this was confirmed with a stinging shock as my finger came closser to the cage than my groundng wire.
In my setup, I have placed a length of flexible 4" hose to be used sort of like a spot clean-up vacuum. During my second run, I used this hose to sweep up some accumulations, and found that I would periodically recieve a shock from the steel reinforcement wire.
I have grounded all my exposed metal parts, and the sparks and shocks have ceased.
Long and short of it (so far): plastic parts - a static field will develop, but no shocks; ungrounded metal parts - definite stinging shock hazard ! - best ground any exposed metal.
Shocks
Finally got my system up and running this past weekend and made lots of saw dust
!While running there was a definite "Static field" around my plastic S&D piping and collection barrel (my barrel is a plastic 55gal drum, cut down to approx 40gal and capped with a clear plastic lid - photo attached.), such that when I got within 3 to 4 inches of the piping or drum, the static would cause the hairs on my arm to stand up. Did not experience any significant shocks however.
Shortly after shutting down, I noticed a sparking sound that would repeat about every 20 seconds. Upon investigation, I discovered a spark jumping between the metal carrying handle of the collection barrel and the metal cage surround the exhaust filters (attached photo). Figuring the swirling of the dust in the plastic barrel was the cause of the static build-up, I grounded the metal handle; however, the 20 sec interval between sparks continued. Thus, the static was not being generated in the barrel, but in the filter stack. Indeed, this was confirmed with a stinging shock as my finger came closser to the cage than my groundng wire.
In my setup, I have placed a length of flexible 4" hose to be used sort of like a spot clean-up vacuum. During my second run, I used this hose to sweep up some accumulations, and found that I would periodically recieve a shock from the steel reinforcement wire.
I have grounded all my exposed metal parts, and the sparks and shocks have ceased.
Long and short of it (so far): plastic parts - a static field will develop, but no shocks; ungrounded metal parts - definite stinging shock hazard ! - best ground any exposed metal.
Attachments
Obviously, your system is an efficient static electricity generator (I remember those big Van de Graaf generators we all saw in high school demos that were usually "hair raising" events). All that dust has a different electron potential that the PVC pipe and moving it through the duct, the cyclone, the plastic bin and the filter bank causes high voltage accumulation on the surface of the non-conducting portions of the system. The metal filter mesh acts as a collector -- as does the wire inside flex duct and other metal items like your hose clamps.
Your best action plan is to tie those metallic parts to building ground with lightweight wire and the problem should go away.
Your best action plan is to tie those metallic parts to building ground with lightweight wire and the problem should go away.
clayandnancy
New member
That's a nasty looking spark.
Resurrecting an old thread here, as I have recently moved to a very dry climate (New Mexico) and have started getting some shocks from the foil tape on the PVC connections, among other things.
My plan is to run a braided ground wire outside the ducting (which is now sealed up) all the way back to the cyclone.
Just wondering where I should tie into ground at the "end of the run", as in, at the cyclone end of things? I thought about using the screw in the outlet cover that the relay is plugged into, not sure if this would be a good idea.
My plan is to run a braided ground wire outside the ducting (which is now sealed up) all the way back to the cyclone.
Just wondering where I should tie into ground at the "end of the run", as in, at the cyclone end of things? I thought about using the screw in the outlet cover that the relay is plugged into, not sure if this would be a good idea.
haurykjo,
While using the screw that secures the outlet cover to the receptacle into which the relay is plugged would probably work, I am not sure this is the most reliable way to establish continuity to ground. Additionally, if the bare copper wire gets trapped between the prongs of the plug as it is inserted into the outlet, the entire duct work could be energized. While unlikely, this potential problem is best avoided.
I established PVC duct work continuity to ground by mounting a grounding clamp to the outside of the relay enclosure. This was done by drilling a hole in the enclosure on the side and scraping paint away from around the hole. The grounding clamp was secured on the outside of the relay enclosure with a tight fitting machine screw and nut. The bare grounding lead from the duct work was secured to the grounding clamp.
Since a properly installed relay box is itself grounded, a grounding clamp attached to the metal relay enclosure establishes continuity to ground. Nonetheless, before making the final connection I checked that there was continuity from the newly installed grounding clamp and the grounding lug inside the relay enclosure. I initially tried a self-taping grounding screw, but found the metal relay enclosure would not tap; therefore I opted for the grounding clamp.
The grounding clamp I used came from Lowe’s and looks like the one pictured at:
http://www.lowes.com/pd_10069-15527-02-18009___?productId=1000213&pl=1&Ntt=grounding+clamps
Although outside the scope of your question, I gave some thought to attaching a bare or insulated wire from the PVC piping to the grounding lug inside the relay box. However, I worried about accidental contact with a live component in the enclosure. Also I did not want to deal with: an added splice to an interior insulated grounding wire extending outside the enclosure; protecting the wire from sharp enclosure edges; and plugging the hole through which the grounding wire passed to keep dust away from the relay.
While using the screw that secures the outlet cover to the receptacle into which the relay is plugged would probably work, I am not sure this is the most reliable way to establish continuity to ground. Additionally, if the bare copper wire gets trapped between the prongs of the plug as it is inserted into the outlet, the entire duct work could be energized. While unlikely, this potential problem is best avoided.
I established PVC duct work continuity to ground by mounting a grounding clamp to the outside of the relay enclosure. This was done by drilling a hole in the enclosure on the side and scraping paint away from around the hole. The grounding clamp was secured on the outside of the relay enclosure with a tight fitting machine screw and nut. The bare grounding lead from the duct work was secured to the grounding clamp.
Since a properly installed relay box is itself grounded, a grounding clamp attached to the metal relay enclosure establishes continuity to ground. Nonetheless, before making the final connection I checked that there was continuity from the newly installed grounding clamp and the grounding lug inside the relay enclosure. I initially tried a self-taping grounding screw, but found the metal relay enclosure would not tap; therefore I opted for the grounding clamp.
The grounding clamp I used came from Lowe’s and looks like the one pictured at:
http://www.lowes.com/pd_10069-15527-02-18009___?productId=1000213&pl=1&Ntt=grounding+clamps
Although outside the scope of your question, I gave some thought to attaching a bare or insulated wire from the PVC piping to the grounding lug inside the relay box. However, I worried about accidental contact with a live component in the enclosure. Also I did not want to deal with: an added splice to an interior insulated grounding wire extending outside the enclosure; protecting the wire from sharp enclosure edges; and plugging the hole through which the grounding wire passed to keep dust away from the relay.
Interesting ideas. Thanks for the replies.
As I mentioned, my situation is more of an annoyance factor, as I keep getting shocked while running the dust collector. But it's irritating enough to make me do something about it.
I've also noticed quite a bit more dust hanging around on the upper part of the cyclone ramp, just below the intake. I assume this is static related as well.
As I mentioned, my situation is more of an annoyance factor, as I keep getting shocked while running the dust collector. But it's irritating enough to make me do something about it.
I've also noticed quite a bit more dust hanging around on the upper part of the cyclone ramp, just below the intake. I assume this is static related as well.
haurykjo,
The problem of eliminating the shocking static electric discharges you are experiencing will probably be addressed with the copper wire running along and around the PVC piping and having continuity to ground, either via the frame of the various machines, as suggested by bababrown, or at the relay enclosure.
As for dust build up in the cyclone at the inlet ramp, I suspect that static charge is probably the force holding fine dust to the cyclone body. But this is a guess. Moisture can also act as “glue” as well.
I am not sure you are really interested so the following is probably more in the “for what it’s worth category”:
Static electricity is a mysterious phenomenon, at least to me, and I am by no means an expert. I did do a little research including reading the web site of Dr. Rodney Cole at MIT, who wrote authoritatively and at length on PVC pipe and static electricity and discharges. Unfortunately, his web site, referenced earlier in this thread, has been deleted by his Internet Service Provider. However, I found his work at:
http://www.woodcentral.com/articles/shop/articles_221.shtml
From what I recall Dr. Cole argued that static charge is generated by dust and air colliding as it moves down the pipe, dislodging electrons. Since PVC is an insulator, these free electrons have nowhere to go and congregate on the PVC pipe and remain in the air stream, unless enough electrons build up and discharge (e.g. a shock or spark). He concluded that the only way to dissipate the static charge on PVC is wrapping the entire surface of the PVC pipe, inside and out with a grounded conductive material. He suggested foil on the outside of the entire pipe which is wired to ground. However, he had no recommendations for dissipating static charge inside the pipe. He did argue that a single grounded copper wire wrapped around a pipe only dissipates a small amount of static charge, leaving most of the charge unabated.
On Bill Pentz’s web site where he addresses static electricity for dust collection, he recounted the efforts of Brent Dugan to deal with static charge on the inside of dust collection pipe. Mr. Dugan installed 2” wide metal foil tape the inside and outside the pipe that was then taken to ground. Mr. Dugan reported satisfactory results after installing the foil tape inside the pipe.
http://billpentz.com/woodworking/cyclone/ducting.cfm#static_electricity
I followed Mr. Dugan’s procedure and installed 4” foil tape on the inside and outside of the pipe and fittings on opposite sides (2 continuous strips), which was then grounded. I have observed no static discharges and little dust seems attracted to the outside of the pipes. Since my CV1800 cyclone body is inside an enclosure, I cannot say whether I have a dust coating on the intake ramp. However, the inside of the inlet where the PVC enters the cyclone looks to be free of dust. In any event, I can say that it was quite a chore to install about 750 feet of foil tape on 60 feet of pipe during a new install and something I am reluctant recommend to you since it would be a major effort required for pipe already in place.
Like I said, for what it is worth.
The problem of eliminating the shocking static electric discharges you are experiencing will probably be addressed with the copper wire running along and around the PVC piping and having continuity to ground, either via the frame of the various machines, as suggested by bababrown, or at the relay enclosure.
As for dust build up in the cyclone at the inlet ramp, I suspect that static charge is probably the force holding fine dust to the cyclone body. But this is a guess. Moisture can also act as “glue” as well.
I am not sure you are really interested so the following is probably more in the “for what it’s worth category”:
Static electricity is a mysterious phenomenon, at least to me, and I am by no means an expert. I did do a little research including reading the web site of Dr. Rodney Cole at MIT, who wrote authoritatively and at length on PVC pipe and static electricity and discharges. Unfortunately, his web site, referenced earlier in this thread, has been deleted by his Internet Service Provider. However, I found his work at:
http://www.woodcentral.com/articles/shop/articles_221.shtml
From what I recall Dr. Cole argued that static charge is generated by dust and air colliding as it moves down the pipe, dislodging electrons. Since PVC is an insulator, these free electrons have nowhere to go and congregate on the PVC pipe and remain in the air stream, unless enough electrons build up and discharge (e.g. a shock or spark). He concluded that the only way to dissipate the static charge on PVC is wrapping the entire surface of the PVC pipe, inside and out with a grounded conductive material. He suggested foil on the outside of the entire pipe which is wired to ground. However, he had no recommendations for dissipating static charge inside the pipe. He did argue that a single grounded copper wire wrapped around a pipe only dissipates a small amount of static charge, leaving most of the charge unabated.
On Bill Pentz’s web site where he addresses static electricity for dust collection, he recounted the efforts of Brent Dugan to deal with static charge on the inside of dust collection pipe. Mr. Dugan installed 2” wide metal foil tape the inside and outside the pipe that was then taken to ground. Mr. Dugan reported satisfactory results after installing the foil tape inside the pipe.
http://billpentz.com/woodworking/cyclone/ducting.cfm#static_electricity
I followed Mr. Dugan’s procedure and installed 4” foil tape on the inside and outside of the pipe and fittings on opposite sides (2 continuous strips), which was then grounded. I have observed no static discharges and little dust seems attracted to the outside of the pipes. Since my CV1800 cyclone body is inside an enclosure, I cannot say whether I have a dust coating on the intake ramp. However, the inside of the inlet where the PVC enters the cyclone looks to be free of dust. In any event, I can say that it was quite a chore to install about 750 feet of foil tape on 60 feet of pipe during a new install and something I am reluctant recommend to you since it would be a major effort required for pipe already in place.
Like I said, for what it is worth.
tamathumper
New member
I've read a lot of conflicting information on static reduction methods - some say nothing will help, some swear on lengths of wire on the outside of the pipe, some use tape, some add screws sticking into the interior,... so far I've done nothing and I don't have a static shock issue, but I'm not doing tons of sawdust at a time either.
For the short term, at least, you can save yourself from shocks by grabbing a screwdriver or similar metal object and touching that to the pipe first.
For the short term, at least, you can save yourself from shocks by grabbing a screwdriver or similar metal object and touching that to the pipe first.
I'm going to try some copper wire on the outside of the pipe, connected to the foil tape at the connections and to the wire in the flex tubing, and see if that helps. I'll let you know.
I also need to assemble my new Supermax 19-38 drum sander which arrived on Tuesday, and hook up the cyclone to that! I've been using a Rockler collapsible/extendable 4" hose off a wye fitting to connect to my lunchbox planer and planned to try that hose on the Supermax's 4" fitting.
I also need to assemble my new Supermax 19-38 drum sander which arrived on Tuesday, and hook up the cyclone to that! I've been using a Rockler collapsible/extendable 4" hose off a wye fitting to connect to my lunchbox planer and planned to try that hose on the Supermax's 4" fitting.
Well, I finished installing the grounding wire to the outside of my ductwork, using sheet metal screws to attach it to the pvc. Seems to be working fairly well, I used the table saw quite a bit last weekend and didn't get many shocks, if at all.
I attached the termination of the wire to the relay box after grinding off a bit of the paint, as suggested by jsbrow.
I attached the termination of the wire to the relay box after grinding off a bit of the paint, as suggested by jsbrow.
priscillamix
New member
I disagree. Read Bill Pentz's section on ducting and you will be more competent than hvac outfits as to dust collector systems. Just follow his basic rules of duct design (like no short 90 degree elbows) and your install will work fine. You do not need to do the speadsheets. There are also many posts that are helpful herein and many good examples of duct design in the gallery. You can do this job.
Bababrown
Bababrown