An electrical shock occurs when your hand or some other part of your body comes in contact with a source of electrical current and your body provides an unintended path and “completes the circuit” between the electric source and ground.   This electrical shock can simply cause a minor jolt; but it can also be fatal!

This unintended path between an electrical source and a grounded surface is called a “Ground Fault,” which means that the electricity or current is leaking or flowing elsewhere than its intended use (such as a hair dryer, electric mixer, lamp or appliance). The path that the current takes to ground is critical. If it’s a piece of equipment, the equipment could be damaged or destroyed. If it’s you, your child or your pet, serious injury, even death, could result.

How much voltage is dangerous?

Electrocution can occur with ordinary household voltages of 110V or less. The real measure of a shock’s intensity is the amount of current or amperage that travels though your body, not necessarily the strength of the source of voltage. In fact, any current over 10 milliamps (0.01 amp) can produce a painful to severe shock; currents between 100 mA and 200 mA (0.1 to 0.2 amp) can be lethal.

Protecting your home and family

A ground fault circuit interrupter (GFCI) is an electrical device that protects people by detecting potentially dangerous ground faults and quickly shutting off the power. In essence, the GFCI device monitors the balance between the current leaving the GFCI device and the current returning to it. If the difference between the outgoing and returning current is equal to or less that 5 milliamps (5/1000 of 1.0 amp), then everything is OK and the device stays on.  Any imbalance greater than 5 milliamps will disconnect the power and prevent the potentially fatal shock.

What locations need a ground fault circuit interrupter (GFCI) installation?

Most local communities follow the National Electrical Code (NFPA) requirements for home GFCI installations (

Dwelling Units: All 125-volt, single-phase, 15- and 20-ampere receptacles installed in the locations specified in (1) through (8) shall have ground-fault circuit-interrupter protection for personnel.

  1. Bathrooms
  2. Garages
  3. Outdoors
  4. Crawl spaces — at or below grade level
  5. Unfinished basements
  6. Kitchens — where the receptacles are installed to serve the countertop surfaces
  7. Laundry, utility and wet bar sinks — where the receptacles are installed within six feet (6′) of the outside edge of the sink
  8. Boathouses

Owners of homes that do not have GFCls installed in all those critical areas specified in the latest version of the Code should consider having them installed.

Other hazards

A ground fault circuit interrupter (GFCI) should be used whenever operating electrically powered garden equipment (mower, hedge trimmer, edger, etc.). Consumers also need the protection of GFCIs when using electric tools (drills, saws, sanders, etc.).

In contemporary homes, schools, park districts, health clubs, etc., there may be other areas where GFCIs would be required, such as near swimming pools, in pool houses, near hot tubs and whirlpools, and in greenhouses near water supplies. And for older or historic buildings, it is important to upgrade with GFCIs and to revise wiring, outlets and indoor and outdoor light fixtures for modern health and safety codes.

Testing GFCIs

All GFCIs should be tested once a month to make sure they are working properly and are protecting you from fatal shock. GFCIs should be tested after installation to make sure they are working properly.

  • To test the GFCI receptacle, first plug a light into the outlet. The light should be on, and then press the “TEST” button on the GFCI. The GFCIs “RESET” button should pop out, and the light should go out.
  • If the “RESET” button pops out but the light does not go out, the GFCI has been improperly wired. Contact a qualified electrician to correct the wiring errors.
  • If the “RESET” button does not pop out, the GFCI is defective and should be replaced.
  • If the GFCI is functioning properly, and the light goes out, press the “RESET” button to restore power to the outlet and the light should go back on.