Can I run the dc ground wire on the outside of the hose?

[knight_toolworks]

I am asking because it causes big chips to jam in my hose. I have been told it will work but it would be nice to see if any others have tried it.

[Gary Campbell]

Steve..
Go right ahead. static will be discharged right thru the plastic. (It is better to wrap the pipe with the wire than just run it along side, but, of course, takes more wire.)
Gary

[nschlee]

I use the 4" clear dust hose that Jet sells, in 10' lengths. It uses a copper spring wire embedded in the hose, just ground one end of the wire, no need for a seperate ground wire. This hose is also relatively smooth on the inside.

[stevem]

The best and easiest solution is to get dust collection hose that has wire already embedded. You would then ground one end of the wire running through the hose wall.
An online hose vendor chosen at random: http://www.ducting.com/Flx_Thane_LD.html

[beacon14]

Actually the best solution is to use rigid round metal duct work for your main lines and short lengths of the flexible hose with the spiral wire for the last few feet to each machine. Look for a HVAC supplier in your area, they usually have heavier gauge material for less money than the big box stores. Using the flexible material for long runs will result in significant loss of airflow due to the resistance created by the ribbed interior of the duct. The round metal duct is not difficult to work with and makes the grounding problem easy to solve. Of course this is just my opinion your mileage may vary.

[myxpykalix]

One thing that causes the static electricity (i have been told) was that when cutting mdf it has a componenet of some type of metal that causes the static electricity (tell me i didn't just dream that). I have seen sparks fly off my mdf on occasion. Maybe someone more knowledgeable can explain this. If you can run it on the inside I think it would be better as i don't see static electricity jumping thru the plastic.

[knight_toolworks]

I have my setup all metal pipe with just flex hose where needed. but with my better dust boot I am stuck with 3" hose for a bit then to 4" I get a lot of splinters when hollowing out boxes and they jam up worse with wire inside. so I will get some wire embedded plastic hose.
sure static goes through plastic. have you never been shocked with static from it? I sure have when it is really dry in my shop.

[Gary Campbell]

Steve...
No one can argue that the wire coil embedded DC hose is the best solution for a must flex situation. It sounded to me that you might be in a bit of a bind, and were obviously concerned about safety, hence the question.

The wire coil that is embedded in the flex tubing is not bare to the inside surface, nor the outside. Static can build on both. Even tho the discharge voltage will probably be higher, static charges on the inside of the pipe will discharge to a wire on the outside just as it would if the wire is sandwiched between 2 plys of poly. In his book "Woodshop Dust Control", Sandor Nagyszalanczy gives very good instruction about grounding plastic pipe used for dust collection. He recommends putting a wire INSIDE on all STRAIGHT sections of pipe, and coiling a wire OUTSIDE to discharge static on the outside. He goes on to give connection details at elbows, etc. It is a pretty comprehensive book, and Sandor is one of the few that recognize that plastic components can be used in DC systems.

With the majority of your system being metal, you should have little or no explosion hazard, so I guess your main concern would be discharge finding its way back to your control board or computer. If properly grounded on 1 end, (I would connect to the metal ducting) a wire wound around the outside should get you by. I would keep the distance between loops at or less than the diameter of the hose.

If you do go shopping for the flex coil hose, remember there are about 3 grades of product. The thicker/costlier product is much less flexible than the thinner/cheaper product. Good Luck!
Gary

[myxpykalix]

I didn't realize static electricity went thru the plastic. See you learn something new here everyday! I bought mine thru amazon.com it looks just like dryer vent hose except it is a thicker mil material and holds up really good.

[knight_toolworks]

yes not worried about safety it is hard for most of us to make enough dust to be a danger. but after running the wire the whole length of the hose I have not had a loss of connection. but I have had lots of chips jamming in the wire.
I finally had to cut cross grain to keep it from happening all the time.

[ed_lang]

My flex hose has wire on the outside and has been working fine for years. I did the same thing on the ShopBot when it was installed.

I have 6" PVC pipe for trunk lines in my shop with wire on the outside. No problems at all.