How crucial is it to ground your DC system?

[ryan.s]

I never realized until recently that if you plumb your DC that it's recommended that you "ground" the plumbing or DC.

Not quite sure how grounding would prevent static electricy build up. Can some of you engineers or electricians out there explain how this works? I'd like to understand the concept of grounding.

Final question is how dangerous is it if the plumbing is not grounded?

Thanks!

[JoeyGee]

**Assuming you are talking about plumbing with PVC. Plumbing with metal does not require grounding**

Oh man...post this question on Woodnet and pull up a chair. This has got to be one of the most debated questions on DC--other than using PVC vs. metal for piping...but I guess it's the same question. Do a search on it, and you'll find more info than you could ever want.

There is no definitive proof (as far as I know) to show there is danger in static electricity in a HOME shop. A few years ago, there was an explosion at the Sauder furniture plant near here, but that is one HUGE dust collector.

Mythbusters actually tested this, and could not generate an explosion with dust and non-grounded PVC pipe. I think (and I will be corrected if wrong) that it's the dust at high velocity moving against the PVC walls that causes the static.

I've got my popcorn in the microwave now...

[LarryG]

IMO, not critical at all.

In my old shop, I've been running a hose-based system with black plastic fittings for almost three years. No grounding (there's a reinforcing wire in the hoses, but it's not connected as a ground). Have never had a problem.

In my new shop, I'm plumbing with S&D pipe and fittings. I'm not going to run a ground wire.

[LinuxRandal]

Both Mythbusters AND the Federal gov, did things on this. It requires a concentration of particles to air, that are not generateable in a home dust collector. Your MUCH MUCH MUCH, more likely to have a fire from burning embers/blade tooth/aluminum/(cuttings) then an explosion.

That said, some people still do it for piece of mind.

[Stytooner]

It's not that critical, however, if you have any metal parts in the system, you better ground those. The only times I have ever gotten bit was from metal pipe that was attached to plastic pipe at both ends. No ground....that is until I brushed up close to it. It hit my son several times as well, so I changed the design back to all plastic in the shop. No more problems. The metal piping is outside now with the DC.

[RHunter]

I remember reading a post online somewhere that an accident/fire investigator determined after much effort and testing, that a fire or explosion in a low yield dust collection system (re- hobbyest) is VERY, if not IMPOSSIBLY REMOTE.

Now that being said, I have S&D drain lines with the wire lined hose running to my router table. After using the router table for 20-30 minutes, if I brush against the hose- I do get bit! Would grounding solve this? No question. Should I go to the trouble and do this to save me from being shocked? Not in my mind.

So I live with the occasional shock...

[IBBugsy]

Just my thoughts after reading the above.....

I guess there is a low probability of having the "perfect" dust conditions (very small particle size and high concentration) in a typical home system to result in a dust explosion but there is plenty of opportunity to generate an electric charge. So if you don't like getting that "surprising shock" when you touch the DC system you can ground it.

My small PVC system has never given me a shock. If yours does and you'd like to stop it, ground the system.

My only other thought, if you do want to ground the system, is that you may have to run the wire on the inside of the pipe to do any good? I've never looked into it so I could be way off but make sure you look into how to do it before any DIY attempts. No use doing it wrong first!

[Ken Massingale]

I don't think so. I have read the horror stories on Woodnet and other places, and that prompted me to get the grounding kit, although I had never had a static shock.
I started to install the ground wire as described in the little booklet that came with it, but since it said to run the wire inside the PVC, and with me not one to waste effort without good cause, I decided to not disassemble all the PVC until I had a static problem. I have tried all I know to do to generate a static charge and as of now haven't.
I have an unopened grounding kit if anyone is interested! ;-D

[SARGE..g-47]

From what has been de-mythed as stated, even though PVC generates a lot of static electricity there is not enough volume in a home shop to set off an explosion, IMO. As also already stated, there is more concern with a fire that could be generated inside the pipe from accumulated dust caused from not generating enough cfm to keep it flowing to the intake.. or something large getting stuck in the pipe creating a blockage. But.. even that is a very remote chance.

But... with that said and having just installed a Penn State cyclone, this ole country boy is going to ground the short run of PVC I have in my system to avoid shock that Lee mentioned. I placed my cyclone in a central location that reaches all 4 of my large dust-makers with a combined total run of only 20'. 10' of that is from the cyclone itself with over-head 6" PVC and 10' of 6" clear flex pipe heavily re-enforced with wire which is self grounding. But.. it's not self grounding in my case as the clear flex pipe is inter-mitten with PVC in the run.

So.. this week-end I have enough left over copper wire to wrap the short run of PVC with wire and attach it to the wire inside the 6" flex pipe it is attached to. I will ground the entire run to the cyclone on that end and the flex pipe with self-contained wire will ground to the work-horse at the other end when connected.

The 10' of clear flex is connected to one of those large dust makers at a time. I intentionally installed 6" ports on each machine to give me a 6" run from cyclone to machine with no loss of efficiency with a down-size in pipe at any point.

Smaller machines which generate less dust have been placed down what I have dubbed as "small machinery row" on an outside wall. I'm making one run of 4" plastic flex pipe down that wall with ports at router table.. SCMS.. 12" BS.. vertical belt sander.. and spindle sander. It will be attached to my existing DC and trash can separator at the end of that run. So... no static electricity problem with that set-up and I have created an ideal scenario (IMO) for both large and small machines and increasing efficiency on both the cyclone and DC by keeping the runs as short as possible to not over-tax either as if I would if it were just one long run from the cyclone alone.

I personally think that most make the mistake of expecting too much by running too far and turning their small particle potential trap into nothing more than a large chip collector with the small particles escaping for the most part. A case of dropping to much cfm from resistance created by that long run.

I have designed both systems for quick connect allowing me to use a ram-rod occasionally as you would on a cannon to insert through piping to clean out any obstructions or build-up of dust clumps that could occur and potentially cause a fire in the worse scenario. Having a large portion of clear pipe allows a visual inspection of that portion of the pipe for better monitoring that particular concern.

Regards...

[Ken Massingale]

Sarge, your shop makes me want to bawl like a baby with a messy diaper................

[bmyers]

I'm no expert but I would think that it would matter what part of the country you are in and what time of year it is. Static electricity builds up when it is not dissipated in some other way, be it grounding, humidity, or your body.

Here in Phoenix where the humidity is actually negative #'s (), static can build up quickly. In Florida at the same time of year, I doubt static would build up quite as much due to humidity.

Fire isn't your only concern though. Let's say you have a fancy lathe with a computer controlled motor. Big jolts of static can fry a motor controller if it's hit the right way.


Bill

[SARGE..g-47]

Afternoon Ken...

Thanks... and I hope it's as beautiful a day in your neighbor-hood up the road a piece as it is in Atlanta. My shop is a culmination of 35 years of tools and ideas accumulated that has finally began to see the last pieces of the puzzle fit together. And I still could use more room as we all could!

I have a ton to do today.. got to make the grocery run.. cut yard and pressure wash the house and drive-way with any luck before we start porting off that 4" flex pipe run latter in the evening.

I intend to come off the "small machinery row" run pipe with 4", then split it with a Y into two 2 1/2" for the SCMS.. router table and 12" Jet band-saw. They will see one line go to the main port in router fence and another to base cabinet shelf built just under the router. The SCMS will get one to the main port and I am going to use the other to a hood I will install behind the fence. BS gets one to main port and one that arcs up and comes down from above the upper bearings for table surface, supported by a flex arm attached to upper casing with magnets much as one of those flex lights. Probably will just one port the vertical sander and spindle sander. Depends on what that achieves. If it is in-sufficient, I will rig a secondary line to where-ever will do the most good.

As a matter of fact, if ya aren't doing anything (yeah, right :>) grab some S.C. bar-be-que and come on down to-night. I'll supply liquid refreshments (even though I don't I haven't partaken personally since my kid became a teen-ager years ago). Got plenty to do and I'll put ya to work!

Regards...

[gsmittle]

Just my thoughts after reading the above.....


My only other thought, if you do want to ground the system, is that you may have to run the wire on the inside of the pipe to do any good? I've never looked into it so I could be way off but make sure you look into how to do it before any DIY attempts. No use doing it wrong first!

I'm trying to remember where I read this--I don't think it was Pentz's site. The writer drove sheet metal screws into the top of his PVC pipe every two feet so that the tips penetrated a half inch or so into the pipe, then connected them on the outside with a ground wire. The theory was that the pointy screws would discharge whatever built-up static into the ground wire.

Of course, my DC system is a ShopVac with a 2 1/2 inch hose and a drywall bag, so I could be talking out of my a$$...

g.

[Tom Miller]

I've been zapped by touching the PVC of my DC -- on drier winter days, it's bad enough that I suppose I'd try to avoid it.

But, it would be nearly impossible to dissipate the charge by grounding, short of metallizing every square inch of PVC (and hose) surface. The whole problem is that PVC is not conductive, so even if you dissipate the charge from one spot, there's that much charge just one inch over.

In fact, recently I went to wipe the inside of a piece of PVC with my hand after I just turned off the DC, and as my fingers moved across the PVC, I got multiple zaps as my finger moved along.

I don't see this as an explosion hazard, and I think trying to run a wire around or through your PVC or hose is, at best, useless.

Regards,
Tom

[Lee4847]

From personel experence.. I have PVC above where I roll out and set up my DW735 Planer. I have a pvc elbo attached to a length of flex hose with the wire reinforcement to connect to the PVC overhead when I am using the planer. EVERY time I would walk past the hose the static would zap me in the arm. After thousands of zaps I bared back a short section of the reinforcement and attached a wire. I grounded the wire and no more zaps! It may not have been dangerous.. but it was deffinately anoying!!