Continuity testers are just that; devices used to indicate the uninterrupted connection in a given wire or circuit. They are (typically) hand held, battery-operated devices. When someone says they’re ‘buzzing out a circuit’, this is what is meant.
They are usually basic, consisting of a pen-type device attached to a probe, or a pocket-sized unit with a pair of test leads. The item or wires being tested are powered down as the device imparts its own voltage into the circuit to ultimately test resistance. An LED indicator and/or buzzer usually indicate continuity.
While we detail standalone devices here, a multimeter also has a continuity tester built in as standard.
Advantages of Standalone Continuity Testers
Although you end up with separate piece of equipment, having a good quality continuity tester in your tool kit can be a big bonus. While the cheapo ones are generally no better than one built into a multimeter, some of the higher quality Extech and Fluke units have great features.
The better ones can put out more current and test longer cable runs, such as up to 500 feet with the Extech CT20 with the inclusion of its remote indicator. These are perfect for longer runs, allowing you to take the indicator to the other end from the tester. They can also indicate polarity.
You may also have varying voltage/current output options depending on sensitivity of circuits to be tested. Some will also have a headphone socket to save annoying folks in the vicinity.
There are also non-contact ‘tracers’ that incorporate a tone that will fade when continuity is lost. These are good for pinpointing the general location of a cable break within a loom, for example.
Sensitivity: Low current, low voltage devices might need to be employed to test those circuits that have sensitive components, where a higher current might cause damage.
Latching: These might need to be used for those scenarios where an intermittent fault is causing issues. Machinery that induces vibration, and those into automobile repair, might come across a scenario where there is no fault at rest. In that case, a latching continuity tester might be employed for the duration of operation.
Multimeter Continuity Test Range
If you already have a multimeter, you won’t need to buy a dedicated continuity tester in most cases as all multimeters have one built in. They vary in usefulness and are pretty basic compared with some of the dedicated ones; putting out nominal current/voltage, but they are fine for most tasks. Fluke’s multimeters are renowned for having the best continuity checkers, being both fast and latching. Multimeter-based ones are usually shared with the resistance position on the dial.
Examples of dedicated testers:
Basic tester for buzzing out wires, fuses, switches etc. A pen-type unit that comes with a 30” test lead / alligator clip.
Sperry Instruments CT6101
Similar to the ET40, albeit a heavy-duty tester. Also pen-type, with a single lead and crocodile clip. Has a bright indicator and okay build quality.
Cont Test Plus
This useful unit by Hi-Tec is a bit more engineered, offering local and remote continuity testing. Pocket sized, it has a remote probe with flashing green/red LED (denoting polarity) and features crocodile clips. Good for diagnosing faults in installed cables.
With the T90 you’re getting into voltage tester territory. It can perform continuity checks to 400kΩ with a loud beep, and measure AC/DC voltage from 12V to 690V. A series of LEDs denotes voltage value. Leads/probes can be neatly docked together. There are other devices in the T range, up to the T150 proving kit.
This cable identifier is a better option for the professional. Especially useful for linemen, it allows one person to test up to 16 lines with its built in transmitter/receiver. This set also includes a basic multimeter featuring voltage and current ranges, and resistance and diode checks. It is CAT-III rated and has an auto power-off mode, along with data hold. Voltage check varies from 5V to 16V.
This unit is a well rated local/remote model. The local tests incorporate an LED and loud buzzer, with the remote part featuring a flashing probe. Features a useful hanging clip.
As to multimeters – as mentioned – if you want a good one that has responsive continuity, look to Fluke. We’ve reviewed dozens of them in this section, with lots to choose from. For example, you can’t go wrong with the Fluke 175; a solid device that features timely continuity tester and auto-ranging with quality build and finish.