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A number of posters on this forum seem to be very critical of neon scewdrivers, and recommend multimeters, but do not mention that multimeters also have a high input impedance and will record sigificant voltages when connected to wiring which is isolated from a source voltage. Such as wires from a switched off FCU.
They forget that electrians' voltage measuring instruments usually incorporate resistive loads between their terminals sufficient to pull these stray voltages down to close to zero.
A multimeter used in this application is quite likely to show a voltage, though less than 230V ac. This should not, in itself, be cause for concern. The cpc in the cable may have sufficient capacitive coupling to reduce this voltage to nearly zero, or it may not.
They forget that electrians' voltage measuring instruments usually incorporate resistive loads between their terminals sufficient to pull these stray voltages down to close to zero.
A multimeter used in this application is quite likely to show a voltage, though less than 230V ac. This should not, in itself, be cause for concern. The cpc in the cable may have sufficient capacitive coupling to reduce this voltage to nearly zero, or it may not.