Most electrical testing programmes involve a number of different tests to be carried out against limited time constraints. This means the electrician needs a testing instrument that is versatile and adaptable as well as being practical and of course accurate. A great example of this is the open-jaw multi-tester.
What is an open-jaw multi-tester?
An open-jaw multi-tester is a non-contact current, voltage and resistance detector which can usually also test for phase rotation and carry out a resistance test. The tool is a slim, handheld instrument with two open jaws at the top to clamp around load points on test equipment. There are also two test probes which can be stored on the reverse of the unit. The front face of the tool has operation buttons and usually a large LCD screen for viewing the test results.
The open jaw design of this instrument allows the current and fixed test leads to be measured for two-pole testing. Just one of the probes can also be used for a single pole voltage test. Using an open jaw instrument means you can check the current without breaking the circuit.
Usually you are able to measure AC up to a certain amperage, typically 200A.
Using an open-jaw multi-tester
The first thing to note about using an open-jaw multi-tester is that it needs to conform to IEC 61243-3:2014 if it needs to be used for safe isolation. The built-in voltage tester on the TIS 8000 instrument supplied by Test Instrument Solutions, for example, means it can be used for safe isolation.
Another feature when using the TIS 8000 is that the test leads that are plugged in to the bottom of the unit can be replaced if they get damaged. This is not possible with all types of open-jaw multi-tester and sometimes will necessitate purchasing a whole new instrument.
So if we are testing a piece of equipment for AC current, we need to turn the unit on and place the jaws of the instrument around one of the live conductors of the equipment. For this example we are testing a fan heater with a 2.5 kW load. With the instrument set to AC you will receive an immediate reading of the amperage when connecting with the jaws. If you get a 10 amp reading, for example, you can compare this with the 2.5 kW load to see if the reading is correct.
By pushing the top button on the front face of the instrument you can scroll through the different tests which include AC voltage, DC voltage, Ohms, diode test, frequency and non-contact voltage. To carry out a voltage test you can connect the two probes directly into a live socket and as soon as the instrument picks up voltage it gives a reading for the voltage that is present at that socket. You can also carry out a single probe voltage test by placing just one probe into the live socket or exposed metalwork - this, together with the non contact voltage function is particularly useful for checking PEN faults before commencing any work.
Readings given by the TIS 8000 are immediate and clearly displayed on the LCD screen.
Open-Jaw multi-tester video demonstration
Below you can check out a product demonstration test for the TIS 8000 open jaw multi-tester:
Please note that this section is for information purposes only. Anyone using equipment referred to in this section must be suitably qualified and/or experienced within the respective field. If in doubt before use, please consult a qualified electrician or engineer & thoroughly read all instruction booklets.