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Pasadena Water & Power

  • Electricity Safety Topics

    Portable/Emergency Generator Safety

    Please keep the following safety tips in mind if you are considering using a portable generator:

    • Have a licensed electrician do any wiring needed to connect the generator to electric circuits. Read and understand the manufacturer's instructions before your generator is connected to your electrical circuits. Plug electric appliances into the generator using a heavy-duty extension cord.
    • DO NOT connect the output of your generator directly to your house wiring or service panel. This can create electrical back feed to the PWP distribution system and put field service crews in jeopardy of receiving severe or fatal electric shocks.
    • To notify PWP of a generator location, please call PWP Customer Service at (626) 744-4005.
    • Warning!! Improper use and connection of a back up or portable generator can be a safety hazard. If you have an electric generator that is, or can be, connected to your electrical wiring, state law requires you to notify PWP of its location. Violators can be subject to fines up to $500 or six months' imprisonment (Section 119090 of the California Health and Safety Code).
    • For tips on selecting the best generator for your home, visit our Guide to Generators page.

    Tree Trimming & Power Lines

    Tree trimming is done by utilities to protect the electrical power lines. State law also requires utility companies to maintain specific clearances (depending on the voltage) between electric lines and all vegetation. Here are some additional reasons for pruning and removing trees near high voltage power lines:

    • Public Safety - to prevent injury to people climbing or working in trees adjacent to power lines.
    • Fire Safety - trees in contact with high voltage power lines can act as an ignition source of fires.
    • Reduce Outages - trees represent one of the largest causes of power outages in California.

    Homeowner prevention can help prevent electric outages, fire, and public safety hazards by:

    • Plant the right tree in the right place. If you must plant trees near power lines, make sure the maximum mature tree height is ten feet away from the closest power line.
    • Trees should be selected so they can reach their full height without the need for frequent trimming.
    • Never allow children to climb trees growing near power lines
    • Never prune trees near electric lines. Call the utility company first to inspect the trees. In many instances the utility may perform the tree work at no cost to the homeowner.
    • Inspect the trees on your property annually for hazards. For expert advice on tree health or hazards consult an International Society of Arboriculture Certified Arborist.

    Electric and Magnetic Fields (EMF)

    (nformation reviewed by the California Public Utilities Commission and the Department of Health Services)

    Can EMF Harm Your Health?

    Many questions have been raised about the possible health effects of 60-Hertz (power frequency) electric and magnetic fields (EMF), which are found wherever you have electric power. EMFs are present wherever electricity flows - around appliances and power lines, and in offices, schools, and homes. Many researchers believe that if there is a risk of adverse health effects from usual residential exposures to EMF, it is probably just at the detection limit of human health studies; nonetheless, the possible risk warrants further investigation. The varying results from epidemiological studies linking estimated EMF exposures with childhood leukemia and one kind of leukemia in adult workers are consistent with a weak effect. Laboratory experiments have shown that EMF can cause changes in living cells. It is not clear whether these changes suggest any risk to human health.

    The results from many research studies will be reported by both national and California EMF research programs to find out if EMF poses any health risk. Given the uncertainty of the issue, the medical and scientific communities have been unable to determine that usual residential exposures to EMF cause health effects or to establish any standard or level of exposure that is know to be either safe or harmful.

    Human studies have not produced a consensus about any health benefits from changing the way people use electric appliances. But, if you feel reducing your EMF exposure would be beneficial, you can increase your distance from electric appliances and/or limit the amount of time you use appliances at home or at work.

    Magnetic Fields at Home (measurements are in milligauss) 

      1.2" away   12" away   39" away  
    Microwave Oven

    750 to 2,000 

    40 to 80 

    3 to 8

    Clothes Washer 8 to 400  2 to 30 0.1 to 2
    Electric Range 60 to 2,000 4 to 40 0.1 to 1
    Fluorescent Lamp 400 to 4,000 5 to 20  0.1 to 3
    Hair Dryer  60 to 20,000 1 to 70 0.1 to 3
    Television  25 to 500 0.4 to 20 0.1 to 2

    Magnetic Fields Outside (utility average)

    Distribution Lines 1 to 80 milligauss under the line
    Transmission Lines 1 to 300 milligauss edge of right-of-way

    National, International and State Scientific Findings

    At the completion of a $45 million federal program, a June 1999 final report to Congress (see http://www.niehs.nih.gov/emfrapid) concluded:

    • "The scientific evidence suggesting that EMF exposures pose any health risk is weak."
    • "EMF exposures cannot be recognized as entirely safe because of weak scientific evidence that exposures may pose a leukemia hazard, but EMF is not reasonably anticipated to be a carcinogen."

    In June 2001, the International Agency for Research on Cancer (IARC) evaluated extremely low frequency (3Hz-3kHz) EMF and found:

    • An association between childhood leukemia and high residential magnetic field strengths was judged "limited evidence" for excess cancer risk in exposed humans.
    • Evidence for excess cancer risks of all other kinds, in children and adults, as a result of exposure to ELF electric and magnetic fields was considered "inadequate".


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