Abstract: A voltage detector has a plurality of voltage detection circuits which, at their respective inputs, are electrically connected in common to a feeler serving as a test probe for contacting a power line conductor. The detection circuits are cascaded in the order of successively increasing individual voltage detection thresholds thereof at and above which they respectively produce output signals in response to the feeler voltage, the arrangement being such that each circuit other than the circuit of lowest threshold is enabled to produce its output signal only upon an output signal being produced by the circuit immediately preceding it. The circuit outputs are connected to respective inputs of a warning signal generator which produces an output warning signal uniquely characteristic of the number of detection circuit output signals it receives and thus uniquely characteristic of the voltage condition of the power line conductor contacted by the probe.