Portable generators are used to generate electricity when temporary or remote power is required. These internal combustion engines prove useful during recovery operations that follow disasters. Portable generators also supply 115 or 230 volts AC auxiliary power and according to the National Electrical Code (NEC), the aim of grounding is to keep the frame of the generator at zero voltage at all times. The reason for this is that when the generator is operating, current could pass through your body, causing a shock. This can easily happen if there is a fault condition, such as bare wires.
Grounding Requirements Using Earth Pin and Metal Water Pipe
There are a number of situations during which the National Electrical Code requires that a portable generator be grounded to a metal water pipe or ground rod. The first of these is when the generator is not part of a separately derived system. The second is when it has a neutral conductor. The third is when it supplies auxiliary power by means other than a plug-and-cord connection. A portable generator that is operating after being placed directly on the ground requires an earth rod that has been driven deeply into the earth. A generator that has been hard-wired to a building's electrical system must also be connected to either a ground rod or to a metal water pipe.
Grounding Requirements When Earth Pin and Metal Pipe are not Required
Grounding the portable generator to a metal water pipe or ground rod is no longer required if the portable generator is mounted on a vehicle and the generator's frame is secured to the frame of the vehicle. In this instance, the vehicle will be a connecting body that serves as a grounding device. The conditions for grounding are met if the portable generator is bolted to the frame of the vehicle. In this case the permanent joining of the metallic parts form an electrically conductive path that ensures electrical continuity. The National Electrical Code will also permit the generator to be connected to the vehicle via a ground wire. In cases where the portable generator has auxiliary power output and a ground pin outlet exists for any equipment that connects to the receptacles, grounding to an earth pin or metal water pipe is not required. Last, in the situation where receptacles are mounted on the generator, grounding to an earth pin or metal water pipe is not required.
Grounding Requirements for the Metal Rods and Metal Water Pipes
This rod must be manufactured from metal, normally copper. It can not be less than eight feet in length and requires a diameter of 0.5-inches. Eight feet of the rod must be driven into the earth. The metal water pipe can be a standard underground water pipe that is in contact with the earth for a certain distance.