Everyone wants a safe work environment. One of the workplace hazards are explosions and fires due to static discharge, but these can be mitigated by grounding equipment. Proper grounding is the only way to ensure true static protection if you are in any environment where the potential for static discharge exists.
Many places ground with heavy duty cast clips, solid copper clips and clamps of all shapes and sizes connected to a wire and attached to drums and pipes throughout a storeroom, plant floor or pumping stations. These are referred to as grounding assemblies or “straps.”
These areas may or may not be perfectly grounded. Even though they may look grounded, it’s hard to tell if it’s done properly. An improper ground could mean safety hazards that can lead to fire or explosions.
First and foremost, it must be determined that access to a fully grounded grounding pin or buss bar is readily available. This will be necessary for a solid true ground and will act as the backbone of the grounding system. Keep in mind, however, that the grounding pin and buss bar must be kept clean so solid metal-to-metal connections are made.
The next step in ensuring that something is properly grounded is to make sure the correct connection device is utilized.
Many times a C-clamp or center spring clip will be used for this connection. This would certainly result in a good connection as the C-clamp can bite into the metal pin or buss bar and the clamp pressure on the center spring clamp is strong enough to drive the teeth into the metal pin or bar. It’s important that the clamp or clip is able to pierce any paint that might be on the surface. The connections on the grounding pin and buss bar must be solid tight connections as maintaining continual connectivity is critical for the integrity of the entire grounding system.
The type of cabling used from connection to connection (grounding pin / buss bar to clamp or clip) will depend on the environment being grounded. If the environment is clean such as a paint mixing room, uninsulated stainless steel wire rope or braided copper can be utilized. In other applications where the environment may contain more contaminants, an insulated wire may and should be considered such as THHN (oil and gas resistant).
Now that the connection to the ground source and wire are complete, focus can be placed on the connection to the can, drum, or tank. This connection can be made with a cast clamp with points, C-clamp containing a point or center spring clip with strong clamp pressure and teeth. The type of connection depends on the type of surface in which it is being attached. If the surface is clean and free of dirt and paint, a center spring clip can work fine. The size of the clip will be determined by the size or thickness of the object being grounded. If the container is dirty or painted the connection will need to be made with a connector which will break through those layers to make a solid metal-to-metal connection. Cast clips with points and the C-clamp with a point are perfect for this application.
Once a connection is made to the first container a “daisy chain” method of connecting the remaining containers in the area can be used. This means that a grounding cable can be attached from container to container to maintain a good ground as long as the series of containers is attached to the one connected to the grounding source. Keep in mind that each grounded container must have a solid metal-to-metal connection with the grounding device. It may be necessary in more caustic environments to wire each container directly to the grounding source. This same approach can be applied to grounding pipes for fluid flow, and even grounding work stations.
Following the above steps for creating a solid grounding system should produce good results and create a safe environment. To confirm that there is good connectivity, take resistance measurements with a multi-meter, ohm-meter or ground analyzer. To ensure entire system integrity, a lead should be placed on the connection on the grounding source (grounding pin or buss bar) and the other on the very last connection in the system. This will incorporate a resistance measurement from point-to-point for the entire grounding system. If the reading taken is zero or approaching zero, the system is well grounded and a safe environment exists. If the reading approaches 1M Ohm then check the connections throughout the system to ensure that there are solid metal-to-metal connections. Once the appropriate measurement is received (zero or approaching zero), you have a good and well-grounded system in place ensuring static protection.