Portable ground fault circuit interrupters (GFCI) are one of the best tools on the market to protect workers from electric shock. Most people are not aware that a shock caused by a 120-volt power tool can be deadly and therefore while working under certain conditions (outdoor, high humidity, or close to a water source) extra precaution should be taken and a GFCI should be used.What does a GFCI protect against?
It only takes about 50mA to cause your heart to go into cardiac arrest. To put that into perspective it takes 10 times that amount to turn the lights on in your kitchen... let that sink in. Not very much, is it? GFCI is designed to protect a person from getting shocks that are greater than 5mA.What does it do?
GFCIs limit the amount of current that can pass through your body to ground. Let's go back to the light bulbs in your kitchen. Normally the current flows through the black wire up to the lightbulb, through the filament, and back down the white wire. If you could somehow reach out and touch the filament, then some of that current would flow through you to ground. This is what the GFCI will notice and trip the circuit before any harm is done.How does it work?
Inside the GFCI is a protective device that measures the difference between the current leaving the device and the current coming back to the device. If the difference in these two currents is ever greater than 5mA (remember 50mA can cause cardiac arrest) the protective device will operate and open the circuit immediately.When should I use a one?
For the most part, you are going to want to use a GFCI whenever you are using cord and plug power tools. You are especially going to want to use one when working outdoors or in a facility with high humidity or nearby water sources.Do I need to test it?
Yes. Each manufacturer will have their own test procedure but they are usually very similar. On the device, there will normally be a black test button, press it in until you hear a click, then press the red reset button to reactivate the device.Final thoughts
Today it is very common that bathrooms would have GFCI receptacles installed in them. In an industrial facility, you might not be so lucky. That's why it's important to have access to portable GFCI devices to protect yourself and everyone else working with extension cords, lighting systems, and power tools.
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