Safety With Electric Tools

Richard L. Parish  |  11/22/2004 7:12:00 PM

Figure 1. GFCI outlet.

Figure 2. Two-prong plug on double-insulated tool.

Electric tools are commonly used in small lawn and garden areas as well as home workshops. Many small string trimmers, edgers, blowers and hedge trimmers are electrically powered.
 
Electric tools have some advantages over gasoline engine driven tools because electric tools require no gasoline or oil, and they require less maintenance. On the other hand, electric tools require a cord, which can be a nuisance, and are limited in power.
 
Although some battery-operated tools are available, they are generally very low in power. Electric tools eliminate the fire hazards associated with gasoline, but introduce the hazard of electric shock or electrocution. There are some steps you can take to improve the safety of electric tools.

Extension Cords
Most electric tools will require the use of an extension cord to reach your lawn or garden. Be sure that the cord you use is adequate for your tool. First, check the amperage rating of the tool (usually found on a nameplate on the tool or on the box the tool came in). The wire size needed for that amperage then depends on the length of the cord; longer cords must be heavier to reduce voltage drop and prevent overheating. The table below shows the correct wire sizes for different loads and lengths:

Conductor  size
(wire gage)
10 ft. 25 ft. 50 ft. 100 ft.
18 10 amps 10 amps 10 amps 7 amps
16 13 amps 13 amps 13 amps 10 amps
14 15 amps 15 amps 15 amps 13 amps
12 20 amps 20 amps 20 amps 15 amps
10 30 amps 30 amps 30 amps 15 amps

If you use more than one cord, you must consider the total length.

Ground Fault Circuit Interrupter
If you are using outdoor electric tools, you should plug them into a GFCI-protected outlet (Figure 1). Most building codes now require GFCI outlets at all outdoor locations. Older homes may not have GFCI outlets. You have several choices of ways to obtain GFCI protection if your outlets are not already protected. You can replace your outdoor outlet(s) with GFCI outlets, you can install a GFCI circuit breaker in your circuit box to replace the breaker in the circuit serving your outdoor outlets or you can use an extension cord with built-in GFCI protection. The first two actions might require that you hire an electrician.

Grounding
Most older tools and some current tools have a three-pronged plug. The third (round) prong is a ground wire. This wire serves to ground the frame of the tool through the ground wire to the ground rod at the house. This protection works only if the circuit is complete. You must use a three-wire extension cord plugged into a properly grounded three-prong outlet. You should never cut off the ground prong on a cord or tool, nor should you use a three-prong to two-prong adapter unless you ground the adapter.

Double Insulated Tools
Many modern tools are double insulated. The housing is insulated from the electrical components, and is generally non-conductive, thus grounding is not necessary. A two-pronged plug is used with these tools (Figure 2).

Water
It is never a good idea to use electric tools around water. If the turfgrass or plants are wet, you should not use electrical tools. Also avoid working with electric tools when the ground is wet or water is puddled on the ground. Avoid running extension cords through wet areas.

Electric tools can be handy around a lawn and garden. They offer a light-weight, low-cost, low-maintenance alternative to gasoline-powered tools, but they must be used correctly to avoid shock and electrocution hazards. Always treat electricity with respect.

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