Do I really need to ground PVC pipe?

In my last shop, I did not ground. Of course I was only in there a 8-12 hrs a week. Now retired and hope to use more in a new shop. I have a ClearVue DC, and 6" PVC SW PVC piping. I have some metal gates and some clear plastic gates. Any drops to 4" go to Rocklers expanding DC coil. In my last shop, the only time I got shocked was my DW 12" planer. I never disconnected it to see if there a short coming from the machine but I suspect there may have been. So do I really need to ground and what is the best way to ground it, externally or internally (internal would create some drag due to friction but in 6" pipe it should be minimal? I also assume it should be connected and grounded back to my 220V DC. Does it need to be connected to anything on the opposite end? Thanks in advance y'all

Understanding that "grounding PVC" is a term from the woodworking vernacular and that we are really adding a path to ground for the static charge . . . it depends on your use and your climate. I live where it is quite dry. The occasional light shock was no big deal but, wrapping a wire about 1 loop per foot of length and screwing it to a known ground cost about $12 and took about 20 minutes so I did. Problem solved. It doesn't have to be overly involved. You just want a better path to ground than "you". ;-)

Tim - I never have. Every once in a while, my hair tries to stand up when I walk under a pipe (but they are pretty low in my shop).

I don’t see the need.

I have a similar set up with 6" PVC and it is not grounded. It works fine for me.

You can't actually ground a PVC pipe as it is an insulator. What you try to achieve is a continuous discharge line to the tool that you are using so that it doesn't become charged up and zap you. If the tool is already grounded that is enough.

The static buildup on insulated pipes that attracts dust to stick to them can only be discharged by putting enough conducting paths on the pipe to bleed off the static. This can be an earthed wire or tape that is wrapped around the pipe. This will stop the dust sticking but won't prevent zaps as they only happen where the static can build up and conductively discharge into you, as for example off a tool or other metal object.

People worry about discharges in a PVC pipe starting fires but even though this is possible, in a large pipe in an industrial application, it has never happened in a small woodworking environment.

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Originally Posted by tim walker

In my last shop, I did not ground. Of course I was only in there a 8-12 hrs a week. Now retired and hope to use more in a new shop. I have a ClearVue DC, and 6" PVC SW PVC piping. I have some metal gates and some clear plastic gates. Any drops to 4" go to Rocklers expanding DC coil. In my last shop, the only time I got shocked was my DW 12" planer. I never disconnected it to see if there a short coming from the machine but I suspect there may have been. So do I really need to ground and what is the best way to ground it, externally or internally (internal would create some drag due to friction but in 6" pipe it should be minimal? I also assume it should be connected and grounded back to my 220V DC. Does it need to be connected to anything on the opposite end? Thanks in advance y'all

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I don't. I researched this before installing my ClearVu with 6" PVC with 6" drops and some splits to 4" PVC and flex. All my gates are plastic. I determined running a wire inside or outside the PVC is not necessary. (It's impossible to "ground" PVC.) I have never received a static shock but I'm not in the habit of touching the PVC with my hand or my nose.

JKJ

If you are not bothered by dust buildup or the discharge of static when you touch the piping I would not ground it. There is no safety concern with ungrounded DC piping. You will never have the exact right dust concentration plus a spark inside the piping. You could get a spark from picking up debris or something but the dust concentration required is quite high and virtually impossible to achieve. My current system has ungrounded metal snap lock piping. My previous system had ungrounded PVC. It held dust and I would ground it if I did it again. I have not seen any buildup on my metal piping.

I have a shop full of ungrounded 6” and 4” PVC ducts With metal gates and have never had a static charge shock. Lots of problems can happen on a theoretical basis but seldom occur in reality.

When it was new my pvc pipes for my DC had a pretty strong static charge. As they accumulated dust inside a a light coating on the outside they no longer have any detectable charge.

I would get a static shock from the plastic flex hose that connected my planer to my metal DC piping. Usually only in the winter when the air is drier. I put a couple of wraps of stranded copper wire around the flex hose and wrapped the other end around an old wrench that just lays on the floor. This seems to work well.
Joe

Is the clearvue plastic cyclone made of conductive plastic or is it just regular styrene or whatever that is an insulator. Does the company say it should be grounded or not? I was told that liquid hydrogen carts have conductive rubber tires and they have a ground wire dragging on the floor. I no longer see grounding straps on police cars or taxi's. I do not think I ever noticed them on fire trucks.
Bil lD.

Grounding dust control equipment is a good idea, bonding across insulating hose and equipment will minimize static charges. There is no safety concern with wood dust of the particle size and concentration handled with typical woodworking equipment. The electrical charge accumulation will be greater as humidity decreases.
Wood/paper dust is explosible in industrial applications in the right suspended concentration and particle size, not our case.

Excluding corn starch I am unaware of an explosion of an organic material originating from a "static" spark, friction yes, not static. My career was in industrial process safety and combustible dust explosion protection.

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Originally Posted by Don Coffman

Grounding dust control equipment is a good idea, bonding across insulating hose and equipment will minimize static charges. There is no safety concern with wood dust of the particle size and concentration handled with typical woodworking equipment. The electrical charge accumulation will be greater as humidity decreases.
Wood/paper dust is explosible in industrial applications in the right suspended concentration and particle size, not our case.

Excluding corn starch I am unaware of an explosion of an organic material originating from a "static" spark, friction yes, not static. My career was in industrial process safety and combustible dust explosion protection.

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I read an article in a trade publication on electrical wiring in hazardous locations and part of it was a discussion on dust concentrations. The author stated something to the effect that for there to be an explosion hazard, the dust in the air would have to so thick that you wouldn't be able to see your hand at arm's length, and that you wouldn't be able to sustain breathing under those conditions.

So no, a dust explosion is not a hazard in a home shop.

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Originally Posted by Frank Pratt

I read an article in a trade publication on electrical wiring in hazardous locations and part of it was a discussion on dust concentrations. The author stated something to the effect that for there to be an explosion hazard, the dust in the air would have to so thick that you wouldn't be able to see your hand at arm's length, and that you wouldn't be able to sustain breathing under those conditions.

So no, a dust explosion is not a hazard in a home shop.

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Frank you are correct for a combustible dust to explode certain conditions must be satisfied as for wood/paper dusts. Explosion testing of a paper dust I am familiar has an lower explosion limit (LEL) of 75-gram/cubic-meter (this quantity in suspension in this volume of air). NFPA and other National/State codes mandate that equipment be designed and operated at a maximum of 25% of the materials LEL.

All jokes aside it does happen, I was working in a food manufacturing facility when a flour dust collector exploded after a piece of tramp metal (failed grinder part) fell into the fluidized material/air stream. In the transport piping the air/material conditions weren't satisfied, but upon entering the larger volume of this 8-foot diameter dust filter it did explode & burn.

So you're saying I shouldn't machine corn in my shop without proper precautions? It seems there's a kernel of truth to the explosion rumor after all.</joke>

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Originally Posted by Matthew Springer

So you're saying I shouldn't machine corn in my shop without proper precautions? It seems there's a kernel of truth to the explosion rumor after all.</joke>

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I thought the explosion rumor was that grounding the ducts would prevent the dust in the ducts from igniting. In Don's story it sounds like the ducts were OK but the filter was the end of the line. (Small joke. Your joke was much better though!)

Many folk don't realize the explosivity of dust, but when conditions are met its devastating. Simple food stuffs in all of our kitchen cabinets - take sugar; Imperial Sugar manufactured in Wentworth, GA - Inferno: Dust Explosion at Imperial Sugar - YouTube
enough wandering off topic, sorry.

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Originally Posted by Don Coffman

Many folk don't realize the explosivity of dust, but when conditions are met its devastating. Simple food stuffs in all of our kitchen cabinets - take sugar; Imperial Sugar manufactured in Wentworth, GA - Inferno: Dust Explosion at Imperial Sugar - YouTube
enough wandering off topic, sorry.

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I friend who was in demolitions in the military long ago said they destroyed buildings such as warehouses by first distributing a large amount of powder with one charge (I think he said they used flour) then ignited the powder. The building imploded rather than exploded.

JKJ

The bigger concern would be the planer.

Sometimes current can leak into the body of a machine. I check voltage from an energized machine to ground when I am setting it up, or working on wiring. One time I found that a band saw was showing 40 volts from the base to ground, when the machine was plugged in, and off. I did some bad wiring.

Now I un-ground whenever possible by having stuff plug in. Lightning came in on the ground, and ruined a $700. table saw motor. I have stuff set up so that it's grounded when plugged in, and isolated when unplugged. It has cost a lot to get all the plugs instead of having stuff wired in to service disconnects, but it's worth it.

Grounding a plastic pipe back to a grounded blower is easy and worth it. The less shocks you get the better.