Grizzly G9958 instruction manual System Grounding, Plastic Duct

the removal of particulate matter, especially saw- dust, since it is durable and completely flexible. Polyethylene is also very economical and avail- able in a wide variety of diameters and lengths for most applications.

PLASTIC DUCT

The popularity of plastic duct is due to the fact that it is an economical and readily available product. It is also simple to assemble and easily sealed against air loss. The primary disadvantage of plastic duct for dust collection, whether black ABS or white PVC and even rubber or polyethylene flex-hose, is the inherent danger of static electri- cal build-up.

System Grounding

Since plastic hose is abundant, relatively inex- pensive, easily assembled and air tight, it is a very popular material for conveying dust from wood- working machines to the dust collector. We rec- ommend using flexible hose (flex-hose) to con- nect the woodworking machine to the dust collec- tor. However, plastic flex-hose and plastic duct are an insulator, and dust particles moving against the walls of the plastic duct create a stat- ic electrical charge build up. This charge will build until it discharges to a ground. If a grounding medium is not available to prevent static electrical charge build up, the electrical charge will arc to the nearest grounded source. This electrical dis- charge may cause an explosion and subsequent fire inside the system.

To protect against static electrical charge build up inside a non-conducting duct, a bare copper wire should be placed inside the duct along its length

Guard against static

electric build up. Ground all dust collec- tion hose and pipe.

and grounded to the dust collector. You must also confirm that the dust collector is continuously grounded through the electrical circuit to the elec- tric service panel.

If you connect the dust collector to more than one machine by way of a non-conducting branching duct system and blast gates, the system must still be grounded as mentioned above. We recom- mend inserting a continuous bare copper ground wire inside the entire duct system and attaching the wire to each grounded woodworking machine and dust collector.

Be sure that you extend the bare copper wire down all branches of the system. Do not forget to connect the wires to each other when two branch- es meet at a Y or T connection. Use wire nuts.

Ensure that the entire system is grounded. If using plastic blast gates to direct air flow, the grounding wire must be jumped (Figure 12) around the blast gate without interruption to the grounding system.

Plastic Blast Gate

Copper Ground Wire Metal Duct

Figure 12. Ground jumper wire when using plas-

tic blast gates and metal duct.

We also recommend wrapping the outside of all plastic ducts with bare copper wire to ground the outside of the system against static electrical charge build up. Wire connections at Y’s and T’s should be made with wire nuts.

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