There are a huge number of test leads that are available on the market today with prices ranging from a few pounds to over a hundred. How do you work out which leads are suitable for the tests that you wish to run?

The first thing you should consider is how many amps will be running through this cable? This is vital as high ampage will very quickly cause a wire to heat up and cause damage to the wire and its surroundings.

Many test leads are fused; this means that the test lead will contain a fuse. This provides an added level of protection to any tester. To help save time and money it is worth ensuring that the fuse limits are appropriate for the tests that are being performed.

All test leads feature standard 4mm connectors meaning that the majority of leads can be used with any piece of test equipment. The exception to this is the new Megger leads. They have short 4mm contacts that typically will only fit in Megger testers.

One important thing to remember when using new leads is that the accuracy of the readings can be affected by a number of different factors.  These can include the length of the lead and if any fuses are present. This can be solved by zeroing a tester before use.

The recommended method to achieve maximum accuracy from your test meter is to ensure you are using the exact leads that are specified with your tester.  This could ensure better results and is one less thing for you to worry about if ever there is a problem.

The most common issues that any cable may have tend to occur because of wear and tear. These problems include:

  • Winding wires too tightly as this can cause the production of heat
  • Nicks and damage to the insulation through either excess heat or direct damage
  • Damage to the core of the wire due to excessive bending or being crushed
  • Dirt or oxidization on the connectors them selves

Many of these problems can be prevented with due care and attention but eventually you will be looking at a having to purchase a new set of leads.

In order to help protect your cables for the maximum period it can be important to ensure that the coating on the leads is appropriate for the environment is will be used in. PVC coated leads are amongst the toughest leads available but can be more rigid compared to other materials. By comparison silicone coating provides a much more flexible lead but is also more likely to suffer damage.

Caged probes used to be incredibly popular because of the way they expand to provide better contact and therefore readings. They are however falling out of favour. To comply with regulations most test probes are shielded, this means that a engineer is protected from the high voltages that may be running through a probe and also provide a extra level of protection against accidental injuries such as stabbing yourself.

The main consideration when purchasing new test leads should be first that the leads are capable of the amps that will be applied and secondly that they are the leads for the tester you own this will ensure a long life for your leads as well as highly accurate readings.


Written by Barry Atkins at