Multimeter test leads are considered to be an integral part of electrical measurement, for example connecting your digital multimeter to the unit under test. If the test leads are in poor condition this can lead to inaccurate readings and could result in a health and safety concern if live wires are being read as being de-energised. A lead kit for measuring high voltage and high energy circuits, such as distribution system voltages (240V- 600V), needs to be in good condition with the proper markings and ratings. You should always take precautionary steps to verify the condition and rating of the leads before testing to ensure safety in the workplace. There are test lead sets designed to meet the requirements of nearly all applications. Checks before you start: Confirm that the multimeter and multimeter test leads are rated for the category and voltage level appropriate for the electrical environment they will be used in. Electrical measurement category ratings are defined by the safety standard, IEC61010 and have four ratings, CAT I, CAT II, CAT III and CAT IV. Inspect the leads to make sure they are safe to use and able to conduct electrical signals accurately. This includes checking that the leads are properly insulated with no cracks through the cables and also checking the connectors are clean and debris-free. Complete a visual inspection first then conduct simple ohms measurement to confirm they are electrically reliable and able to carry a signal within allowable loss parameters.