Grounding a Portable Generator: Tips and Tricks

A portable generator is great tool to have because it can provide electricity wherever you are. It can come in handy for both work – say, as an energy source for power tools at a work site – and for play, allowing you to power your electrical devices on a camping trip or light up an outdoor party.

Portable generators are generally safe to use, but it’s important to take the necessary precautions. It may be necessary to ground your generator in certain situations, and you should be able to recognize such a situation and know how grounding should be done.

Whether or not your generator needs to be grounded will depend on what type of generator you have and what circumstances you’re using it in. This article will give a basic definition of grounding, explain when it needs to be done and indicate how it can be done safely.

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What “Grounding” Means

Grounding is a safety measure by which an electrical circuit is connected to a low-resistance path for electricity to harmlessly flow away in the event of a short circuit that interrupts its normal flow.

For many modern generators, their metal frame provides that low-resistance path for electricity to flow into the ground. But some generators require you to connect a grounding rod to their transfer switch in order to provide this path.

It’s important to know whether your generator needs to be grounded externally, because a generator that is not grounded at all can accumulate an electrical charge, which may even cause it to burst into flames.

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Electrical Principles

As an electrical current flows through a circuit, it comes in two forms and travels through two sets of wires – negative and positive. The imbalance between these two charges is what causes the movement of electrons from negative to positive. When the circuit is interrupted (a “short circuit”), an electrical charge can accumulate in the wires and in adjacent conductors, such as metal parts. If you touch an object where charge has accumulated, you will be shocked.

Grounding is a safety measure taken in case of a short circuit. It provides a secondary path of least resistance for the electrical current to flow into, usually terminating in a copper rod dug into the ground. This avoids the problem of the charge accumulating and shocking someone or causing an electrical fire, directing the excess current harmlessly into the ground instead.
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Is Grounding Always Necessary for Portable Generators?

No; whether grounding is necessary or not depends on your generator. Most modern generators are designed to be naturally grounded, making external grounding unnecessary.

As mentioned earlier, modern generators are usually grounded through their metal frame. All their metal parts not intended to carry a current, such as the engine and the fuel tank, are “bonded” (or connected) to the frame so that none of them can have significantly different electrical potentials – such a difference being necessary to for the flow of electricity, and thus, an electrical shock.

If their metal parts are not bonded to the frame, as is sometimes the case with older generators, then the generator has a “separately derived system” and must be grounded. That doesn’t mean that you need to check the bonding on your generator; there are a couple of other more obvious indicators of whether your generator needs to be grounded or not.

Firstly, check the operating manual. It should indicate whether the generator needs to be grounded or not. Another surefire way to know if the generator needs to be grounded is to check the transfer switch. If the switch has an option allowing you to transfer electrical current to a ground conductor, that is a good indicator that the generator needs to be grounded. If no such option exists, the generator likely does not need to be grounded.

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How To Ground a Portable Generator

If you have realized that your generator does need to be grounded, than you will need to know how to do so safely. Here is the basic procedure, broken down into steps:

1) Emplace the copper ground rod

To begin with, you’ll need a copper grounding rod and a hammer or mallet to drive it into the ground with. In order to get a solid ground, pound the grounding rod at least four feet into the ground. This may prove difficult in some soil, especially if there are lots of rocks. To make the job a little bit easier, you can use water to soften up the earth. The grounding rod can also be inserted at an angle if necessary, though this angle should not exceed 45 degrees.

2) Connect the copper wire to the grounding rod

Once you have placed the grounding rod, take some copper wire and strip off about half a foot to a foot of insulation from one end, using a wire stripper. Then, use a pliers to tightly wrap the exposed copper wire around the part of the grounding rod that is sticking out of the ground.

3) Link the generator to the grounding rod

After having connected one end of the copper wire to the grounding rod, take the other end and strip off a couple inches of insulation, again using your wire strippers.

With the generator turned off, find the grounding bolt, and loosen the nut. Use your pliers to wrap the exposed, unconnected end of the copper wire around the grounding bolt. Then secure the wire in place by retightening the nut you loosened previously. Your generator has now been grounded.

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A Note on Bonding Versus Grounding

“Grounding” and “bounding” are two words that are used frequently when talking about electrical safety measures. As was explained earlier, grounding is the secondary connection of an electrical circuit to a low-resistance path for electricity to harmlessly flow into in case of a short circuit.

Bonding, on the other hand, refers to the practice of electrically connecting all exposed metal objects not meant to carry electricity in a space or on an object as a means of protection from electric shock. In the case of a generator, that means connecting all of its metal parts – the engine, possibly the fuel tank or metal housing – to the frame, which, in modern generators, usually serves as the ground.

Bonding is something that should only be done and tested by a trained electrician with the requisite tools. If your generator has been properly bonded, it likely does not have a “separately derived system” and will not need to be grounded externally.

If you are still in doubt about whether your generator needs to be externally grounded after reading this article and checking the operating instructions, don’t hesitate to contact a licensed electrician. Better safe than sorry!

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