Only a receiving instrument is required for passive location. This is a great convenience, as it implies very simple operation. It enables a digging crew to be provided with a simple-to-use locator which will enable them to avoid striking buried lines, and thus give them considerable protection against accidental contact with a live power cable, as well as avoiding the consequential disruption and loss from severance of a line.
Active location implies a two part locator, a transmitter and a receiver. Use of active location is essential if target lines are to be positively identified and traced.
Radiodetection locators combine both passive and active forms of location; choice is by simple switch setting and use of a separate transmitter for active work.
Combining the two modes in a single set of equipment gives the user many possibilities. For instance, lines located during a passive sweep can then each be traced with an active signal to a point where they can be identified. When an excavation is planned to a line that has been located and identified with an active locator, the area can be given a passive sweep to check if there are any other nearby lines that are at risk of being damaged during the excavation.