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Protection class 2 (double or reinforced insulation, protective insulation)
CAT I
Measuring category I for measurements at electrical and electronic devices that are not directly supplied
with mains voltage (e.g. battery-powered devices, protective low voltages, signal and control voltages,
etc.)
CAT II
Measuring category II for measurements at electrical and electronic devices connected to the mains
supply directly with a mains plug. This category also covers all lower categories (e.g. CAT I for measuring
signal and control voltages).
CAT III
Measuring category III for measuring in building installation (e.g. outlets or sub-distribution). This category
also covers all lower categories (e.g. CAT II for measuring electronic devices). Measuring operation in
CAT III is only permitted with measuring prods with a maximum free contact length of 4 mm or with cover
caps above the measuring prods.
CAT IV
Measuring category IV for measurements at the source of the low-voltage installation (e.g. main distribu-
tion, building handover points of the energy suppliers, etc.), and outdoors (e.g. work at earthing cable,
outdoor line, etc.). This category also contains all lower categories. Measuring operation in CAT IV is only
permitted with measuring prods with a maximum free contact length of 4 mm or with cover caps above
the measuring prods.
Earth potential
For safety and approval reasons, unauthorised conversion and/or modification of the device are not permitted.
Consult an expert when in doubt as to the operation, safety or the connection of the device.
Meters and accessories are not toys and have no place in the hands of children!
In commercial institutions, the accident prevention regulations of the Employer’s Liability Insurance Association for
Electrical Systems and Operating Materials are to be observed.
In schools, training centres, computer and self-help workshops, handling of meters must be supervised by trained
personnel in a responsible manner.
Ensure before every measurement that the meter is not set to another measuring range. Also observe that the
HOLD button has not been pushed at the beginning of the measurement (display with the HOLD button pushed:
“H”). If the HOLD function is activated before commencement of the measurement, no measured value is displayed!
When using the measuring lines without cover caps, measurements between the meter and
the earth potential must not be performed above the measuring category CAT II.
When measuring in the measuring category CAT III, the cover caps must be pushed onto the
measuring prods to avoid accidental short circuits during measurement.
Push the cover caps onto the measuring prods until they latch. To remove, pull the caps from
the prods with a little force.
The measuring prods have to be removed from the measured object every time the measuring range is changed.
The voltage between the connection points of the meter and earth potential must not exceed 600 V DC/AC in
CAT III.
