I'd like to present a little different perspective and qualify that by saying I am not a professional woodworker and only do it as a hobby. Therefore, my use of the dust collector is not constant. I have had an Oneida cyclone with an internal filter for almost 15 years. The last 8 years or so, I have used it installed in one spot with metal ducting run to 3 locations; 2 reduced from the main line to 4" from the 6" outlet and the other and main ducting are 5". This is 1 1/2 HP unit, 110V. I currently only use it for my planer and my jointer, using a CT48 and Fein vac for other jobs. I haven't used a table saw since getting my TS55 but used to use the dust collector for the table saw also (not very effectively though). Anyway all that leads to the issue of metal versus plastic and grounding. I used all metal ducting which was supplied by Oneida after they helped design my ducting plan. I did not ground it and I don't even believe Oneida recommended it but don't remember after 8 years. I have never gotten a shock from any of the ducts, tools or plastic flexible connecting hoses. Now, that could be because all electrical boxes are grounded properly, that all of my flexible plastic hoses have spiral wire reinforcing inside, and I am on a concrete floor in the basement (although I'm not sure that has anything to do with it). Anyway, there has never been any static buildup that I have notice or felt no matter how long I've run the planer or jointer. Before doing the ducting I read too many articles to count where grounding and not grounding were discussed. I could never come to a conclusion and would not recommend either way. I just wanted to let you know that, without grounding on my system, I don't have a problem. It would seem to have been a lot of extra work for nothing on my system at least.