Question: If plastic pipe is grounded to prevent arcing of static electricity, why do the squeeze tools need to be grounded?
Answer: Static electricity is always present with polyethylene (PE) pipe. A static charge can be generated by the geometrical change in the pipe diameter during the squeeze-off procedure. These static charges are only dangerous when arcing occurs. During the squeeze-off procedure (i.e., when the PE pipe is flattened), the gas flow velocity through the squeezed area increases. High velocity dry gas, especially with particles present in the flow, can generate a static electric charge on pipe surfaces, which can discharge to ground.
There have been incidents where company personnel have received an electric shock while operating a squeeze tool that was not grounded, and fires have ignited in the excavation. It is important to understand that a squeeze tool can be a source of ignition, so proper grounding must be employed!
Tip: In addition to grounding PE pipe and squeeze-off tools, separate grounding devices are needed for cutting tools (e.g., wheel cutter, guillotine, saw). The goal of any squeeze-off procedure is to ensure that it is performed properly and safely on polyethylene pipe.