10.1 Relevant Guidelines
Guidelines on limits of exposure to power frequency EMF were issued by the International Commission on Non-ionizing Radiation Protection (ICNIRP) in 1998. The guidelines were recognised by both the World Health Organisation and the Hong Kong SAR Government. CLP Power has adopted the guidelines in total. EMF generated from the proposed overhead line shall comply with the guidelines as in Table 10-1 below.
Table 10-1 Guidelines on Limits of Exposure to 50Hz Power Frequency Electric and Magnetic Fields Issued by ICNIRP
Electric Field Strength
Magnetic Flux Density Millitesla (rms)
calculated values on maximum loading basis are shown in Table 10-2
below. Table 10-2 Electric
and Magnetic Field Calculated for the Proposed 132kV Supply Circuit from Pui O
Substation to Cheung Chau Substation The
calculation is based on the assumptions of maximum loading conditions and
adoption of overhead transmission lines. The typical pole configuration with
the bottom conductor is assumed at the minimum safety clearance from ground
level of 6.7m. Calculation format for
EMF values is acceptable to Electrical & Mechanical Services Department. In
the proposed 132kV and 11kV, 35mVA units new 132kV underground and submarine
cable circuits. As a result, the actual
EMF at the sensitive receivers will be further reduced.
The assessment results
demonstrate that the exposure of the
public to the EMFs generated from the proposed underground cables, cables in
tunnel and submarine cables will not exceed the guideline values laid down by
the Government. As a result, no mitigation measure is required.
measurement of similar design circuits and calculations of EMF for the proposed
underground cables, cables in tunnel and submarine cables demonstrated that the
predicted values would be well under the stipulated guideline limits issued by
ICNIRP. In order to verify compliance with the ICNIRP guideline levels, field
measurements will be carried out within six months after commissioning of this
CLP will directly make arrangement with EMSD for
the necessary measurements at critical locations at both ends close to the
respective substations and the tunnel portals.
EMFs for the proposed underground cables, cables in tunnel and submarine cables demonstrated
that the predicted values will be well under the stipulated
guideline limits (below 2/5 of guideline limits) issued by the
ICNIRP. As such, the existence of EMF
associated with the proposed project is not anticipated to pose any adverse
impact on public health.