7.16.1 - Types of reduced
voltage
Most installations operate at low voltage,
which is defined as up to 1000 V ac or 1500 V dc between
conductors, and up to 600 V ac or 900 V dc between conductors
and earth. Extra-low voltage is defined as not exceeding
50 V ac or 120 V dc between conductors or from conductors
to earth. Four types of reduced voltage system, all intended
to improve safety, are recognised by the Regulations. They
are:
1. - separated extra-low voltage
or SELV {7.16.2},
2. - functional extra-low voltage
or FELV {7.16.3},
3. - reduced voltage {7.16.4},
4. - voltages at values lower than
the maximum for ELV may be required to ensure the safety
----- of people and of livestock
in areas where body resistance is likely to be very low
{7.6}.
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