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Environmental Health Investigations Branch


Annotated Checklist

Program Development
  • share Checklist with the school building advisory committee and other interested groups
  • include Checklist in the materials given to the architect and engineers
  • define extent of local school district EMF policy (this checklist plus or minus other features)
During the Program Development phase of the project, the key activities regarding EMF are communicating information to and involving all interested parties and establishing an EMF policy for the project. Each school project team can take guidance from the various interested groups (school officials, parents, teachers, staff, and students, as appropriate) and must balance the value of achieving lower EMFs against the realities of available funding. The approach of using no and low cost techniques should not appreciably increase construction costs and should not create controversy. Establishing specific magnetic field strength standards, on the other hand, may well foment discord regarding the exact limits of the standards. In all cases, issues of equity must be addressed so the economic and social aspects which may impact society unevenly can be discussed and judged openly.

Site Selection
  • visually inspect site for electrical facilities
  • check with local electric utility regarding present and future electrical facilities
  • consult with local electric utility about reduction options
  • consider alternate sites
  • assess whether undergrounding distribution lines and power feed is a no or low cost option
  • contact the State Department of Education for state requirements
EMF Sources

Possible sources of EMF at school sites include electric lines, substations, and adjacent transmission or distribution facilities. In addition, wiring within the school, especially distribution panels, may also be a significant source of magnetic fields and is discussed in Construction Documents (below). Each source type can produce fields of varying strengths and characteristics.

Similar-appearing electrical utility lines can produce drastically different fields depending upon the specific configuration and amount of current present. In some instances fields may be reduced by reconfiguration of cables or changing of the phasing, while in others this same type of measure may provide no decrease. When there is concern about electric utility facilities it is advisable to consult with the utility to determine the range of possibilities available and the degree to which the utility is willing and able to assist the school to reduce fields.

Electric utility facilities at a given site will influence the flexibility available to make changes. For example, if all of the load flow is in a consistent direction, phase cancelation between circuits can be optimized. If the loads occasionally change direction, however, it will be impossible to have a phase relationship which will always be optimal. Thus, two visually identical electrical distribution structures can have quite different field levels and entirely different adjustment possibilities.

California Department of Education Requirements

The California State Department of Education enacted requirements (as opposed to "suggested guidelines") in 1989 and 1993 for setbacks from electrical transmission lines for new schools. For 50-133 kV lines school property must be at least 100 feet (30 meters) from the edge of the easement. For 220-230 kV lines the distance is 150 feet (45 meters). For 500-550 kV lines it is 350 feet (107 meters). The regulations, which require the school district to verify these distances with the State Department of Education, were set using the formal regulatory adoption process through the Office of Administrative Law.
3 The rationale for this regulation was that at these distances the electric field from the transmission lines would be near background levels. There was no medical risk basis for these distances.

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