grounding dust collection question

[zapdafish]

I finally finished my thien top hat build and while testing it out got shocked alot.


:5eek::5eek::5eek:

I am using 6" wire reinforced hose but they are being connected to my tools with plastic fittings and then the top hat is a big wooden thing that also prevents the static charge from going anywhere. If I expose some of the wire in the hose and then use alligator clips to connect one end to the tool and the other end to a ground, will that fix the problem? I am hoping to avoid having to buy a grounding kit and then looping the copper wire around my hose. The wire reinforcement looks like steel.

 

[Glennbear]

Without getting too deeply into electrical theory I have some thoughts. Static shocks occur when there is difference in electrical charges between two objects. The way to eliminate shocks is to bond the two objects together. The grounding kits sold with the copper wire address a non-problem since there has never been a documented instance of a dust induced explosion in a home shop.

 

[bluedawg76]

I finally finished my thien top hat build and while testing it out got shocked alot.

Could you be more specific i.e. you get shocked when you touch what with what running? I don't think a typical DC setup should be generating that level of static charge buildup. I'm wondering if there is a more serious electrical problem lurking around?

 

[zapdafish]

I have a 10' section of wire reinforced hose that I run from the separator to my tools. The separator is made of plywood and I connect the hose to my tools with a fazlock connector like so

If I touch the hose while the dc is running it is very prickly as the staic buildup has no place to go except into me

When I get home tonight, I can try and upload some pics of the actual setup if needed.

Could you be more specific i.e. you get shocked when you touch what with what running? I don't think a typical DC setup should be generating that level of static charge buildup. I'm wondering if there is a more serious electrical problem lurking around?

 

[zapdafish]

I love my tools but not that much :rotflm:

The way to eliminate shocks is to bond the two objects together.

 

[merrill77]

I am using 6" wire reinforced hose but they are being connected to my tools with plastic fittings and then the top hat is a big wooden thing that also prevents the static charge from going anywhere. If I expose some of the wire in the hose and then use alligator clips to connect one end to the tool and the other end to a ground, will that fix the problem? I am hoping to avoid having to buy a grounding kit and then looping the copper wire around my hose. The wire reinforcement looks like steel.

The problem is that grounding the wire in the hose only grounds the wire. The plastic, which may be where you are gettting the shock from, cannot be grounded because it is an insulator. A static charge only exists on the surface of an insulator (it is static because it is on an insulator and therefore cannot move).

The insulator kits are snake oil, IMO. They cannot work (except for a very small region immediately adjacent to the wire) because the static electricity cannot move across the insulator to the wire (otherwise, it would not be static). If you only touch the hose by the part where the wire is wrapped you're ok, but the rest of the hose will still hold a charge. With a solid pipe (e.g. PVC) you can wrap the entire surface with a metallic tape and then ground that. This is all theory of course - the plastic is not a perfect insulator just like wires are not perfect conductors and there is a long list of other factors to consider that my (long-forgotten) electrical engineering degree don't help me answer. It is easy enough to try grounding the wire though - I think we'd all like to hear the result of that experiment, positive or negative.

Raising the humidity in your shop can help as well, since that increases the conductivity of the air and helps to dissipate the static charge. Never thought I'd need to recommend that in NC!

 

[McRabbet]

There is long standing debate on this issue but be assured that there is not a fire hazard in a home/hobbyist dust collections system (see this link). The best solution is add Mettalic HVAC tape to the outside of the PVC and attach a copper wire to the coiled wire in any section of flexible dusct or around joints and blast gates, and then connect to an earhtern ground. This should dissapate any static electricity charge that is built up on the surface of the PVC (remember that PVC is an insulator and the charge is one the surface). See this section of Bill Pentz's site for more details.

 

[DWSmith]

No matter if the plastic is a conductor or not, safety says to thoroughly ground your dust collection across any wooden pieces, from tool to DC to a solid ground. Just because there has never been the reported case of a static caused dust explosion in a home workshop doesn't mean they haven't happened. Ground the thing and the shocks should stop.

When using my Delta portable planer and got shocked a lot. Once I grounded it to the DC system and that to a ground, the shocks stopped.

 

[junquecol]

I bought my Delta 15" planer used. Previous owner had attached a piece of wire with alligator clip he then attached to wire spiral in DC hose. I can't truly say about grounding of plastic pipe, but in my shop I use 4"PVC with both internal and external grounding wires, with the exception of a 3' piece. Only on this piece (on outside) does dust from the air collect.

 

[zapdafish]

Thanks for the info. I wasn't really concerned about explosions as I was about getting zapped.

I got some alligator clips and found some old speaker wire but was too tired to strip the wire and do any testing last night. I'll be testing to see how it goes later today.

 

[ehpoole]

I am using 6" wire reinforced hose but they are being connected to my tools with plastic fittings and then the top hat is a big wooden thing that also prevents the static charge from going anywhere. If I expose some of the wire in the hose and then use alligator clips to connect one end to the tool and the other end to a ground, will that fix the problem? I am hoping to avoid having to buy a grounding kit and then looping the copper wire around my hose. The wire reinforcement looks like steel.

There is no technical/safety reason that necessitates grounding a hobby-grade dust collection system. However, as you have just discovered, there is a singular practical reason for doing so. To answer your question, it is perfectly fine to bare one end of the coiled wire that reinforces the hose and ground it. You only need to ground it at one end. Moreover, you only need to ground the specific section that you have problems with (for me it is the length that I will connect to my power sanders).

In this instance grounding is effective because the charge that is zapping you is the charge stored in the reinforcing wire (not the plastic of the hose). If you were using a length of hose without wire (all plastic) you would also avoid getting zapped even without grounding.

 

[ehpoole]

PS - I should also mention that simply wrapping all the exposed metal surfaces (wire included) that can transfer a static shock to you with electrical tape should also suffice. It is when your hand (or other body part) gets too close to the exposed and static-charged metal surfaces (reinforcing wire, hose clamps, etc.) that you get zapped. It is very rare for the plastic of the hose to carry/conduct enough of a static charge to shock you.

HTH

 

[Alan in Little Washington]

Wrapping just the part of the hose you touch with grounded foil tape helps.









Grounding the operator and assistants helps too:

 

[ehpoole]

Way too cute!

 

[zapdafish]

hehe, thats pretty funny.

Well, I ran the DC today and couldn't get it to shock me so I didn't do any grounding. Hooked it up to my tablesaw, bandsaw, and planer and no shocks at all.

Switching to a top hat separator and 6" hose is amazing. My HF DC used to not be able to keep up with my jointer. I was planning on replacing it once I got the top hat finished. Now I won't need to.

 

[Canuck]

hehe, thats pretty funny.

Well, I ran the DC today and couldn't get it to shock me so I didn't do any grounding. Hooked it up to my tablesaw, bandsaw, and planer and no shocks at all.

Switching to a top hat separator and 6" hose is amazing. My HF DC used to not be able to keep up with my jointer. I was planning on replacing it once I got the top hat finished. Now I won't need to.

Steve

I too have the HF DC with a Thien separator can. I too have experienced static discharge at times. Usually when it happens, I have been running my planer (DW735). Very dry wood running over the flat bed generates the static. (Much like dragging sock feet over carpet and touching a ground.)

Wayne

 

[uncledavid]

LOL at Alan........

 

[Glennbear]

hehe, thats pretty funny.

Well, I ran the DC today and couldn't get it to shock me so I didn't do any grounding. Hooked it up to my tablesaw, bandsaw, and planer and no shocks at all.

Switching to a top hat separator and 6" hose is amazing. My HF DC used to not be able to keep up with my jointer. I was planning on replacing it once I got the top hat finished. Now I won't need to.

I am glad that it all worked out. :wsmile:

 

[reprosser]

I felt a strong static charge on my Clearvue cyclone this weekend. I could hear the arc, and was able to capture a video.

http://s20.photobucket.com/albums/b205/reprosser/WaterTankRd/?action=view&current=DustArc.mp4

This is at the connection of the flex tubing to the bin connector. I probably will just leave it as-is for now. It was a dry day and the first time I noticed it.

 

[ehpoole]

This is at the connection of the flex tubing to the bin connector. I probably will just leave it as-is for now. It was a dry day and the first time I noticed it.

FWIW, I would suggest grounding the spiral hose wire as soon as practical because the continued arcing will continue to enlarge the hole in the hose (the heat from the arc slowly melts the plastic). The fix can be as simple as securing one end of a wire to a well grounded section of your DC (using a bolt or self-tapped screw connection) and then tightly wrapping the opposite end of a bared-wire around any part of the spiral hose wire. You just want to direct that static charge to someplace where it can do no damage.