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Identifying measurement errors from electrical testing

April 24th, 2015 by Tanbir Leave a reply »
     




electrical-testing-page-backgroundWhen it comes to electrical testing, collecting and collating accurate results is crucial. Those responsible for testing, such as electrical installers, inspectors or contractors, must have an effective system in place to confirm and record the precision and consistency of instruments.

If not, test equipment could be giving out the wrong results, which can be quite dangerous and have potentially serious consequences. Despite being built to high standards, test instruments can stop working properly if they have been dropped on site or suffered damage in the back of a vehicle for instance.

On top of that, human measurement errors can also lead to inaccurate readings according to Electrical Safety First. Thankfully, the majority of these mistakes can be identified and rectified fairly easily.

Here is Instrotech, an authorised distributor for a wide range of electricians testing equipment, with a guide on how to identify measurement errors.

Why errors are made

There are various sources of error that can affect the overall accuracy of a test measurement. What’s more, these can also have an impact on the ability to make a meaningful measurement too.

A lot depends on the type of measurement being made as well as the effectiveness of the connections between the instrument and the circuit being tested. Having said that, measurement errors can occur because of the following:

  • Bad probe contact
  • Poorly nulled test leads
  • Weak crocodile clips
  • Faulty leads
  • Leads other than those supplied with the instrument

Error solving examples

  • Test leads – If connectors are poorly maintained or too old, the chances of making a measurement error is increased. Remember that test leads do naturally wear out over time. It is also possible to remove the effect of test lead resistance (including fuses) by the nulling (zeroing) function on many of today’s test instruments.
  • Probe contacts – Although the condition of probe clips will make a difference, other variables include the material to which they are connected and the pressure applied.
  • Crocodile clips – One common problem with crocodile clips is that one side may have a lower resistance than the other. This can also be a problem when nulling and attaching the clips for measurement.

Insulation resistance and loop impedance testing

When carrying out these procedures, measurement errors can occur for various reasons.

  • In-circuit components – Insulation resistance values can be affected by electronic components.
  • Mains noise or disturbances – This can create variations in results, but repeating the test can put your mind at ease.
  • Instrument accuracy and resolution – If circuits do not incorporate RCD protection, each fault loop impedance measurement should be made with the higher test current range (up to 25 A).

In addition to providing operational instructions, test instruments and equipment should also come with information about sources of error. If not, you may want to search online for manufacturer advice should you encounter any inaccurate or variable results.

Alternatively, contact Instrotech for more help and guidance on how to identify and eliminate errors or to purchase the latest electricians testing equipment.  They are on-hand to provide you with the relevant advice that you need

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