MULTIFUNCTION TESTER – SAFETY TESTING

[Barry Atkins]

A Multifunction Tester is an electronic instrument which is used to perform electrical safety tests in several kinds of electrical circuits. A Multifunction Tester is usually a portable, easy to handle instrument whose cost can vary depending on its safety functions, its accuracy and its certification. Multifunction Testers are mainly used by electricians in order to ensure the safety of specific electrical appliances and installations.

But why is electrical safety testing performed and in which cases is this required?
Depending on each country's regulations, it is obligatory to test not only fixed equipment (cables, lights, sockets, etc.) but also portable appliances. In the last case the tests are described as PAT (Portable Appliance Testing) and they concern every appliance that is connected to a mains supply and requires electricity in order to operate.

The frequency of the safety electrical tests that have to be carried out varies depending on the type of the installation (domestic, commercial or industrial) according to each country's legislation. In the UK, the 17th edition of the British Standard BS 7671 "Requirements for Electrical Installations" defines the testing and inspection procedure across a variety of locations and equipment including medical institutions and equipment, offices and computers, or maintenance gangways and electrical circuits.

There are various types of Multifunction Testers. There are testers which simply show a Pass / Fail result. There are testers which display readings for each test and they require interpretation by an authorized person with electrical qualifications. There are battery operated and main power operated testers. There are testers which can store data in their internal memory or communicate with a PC.

Pat Testers - Most of them perform, at the least, the following electrical safety tests:

• Earth Resistance Test: This test measures the resistance between the earthing rod and the connection leads.
• Earth Continuity Test: This test verifies the integrity of the protective bonding of an electrical device. A current (from 100mA up to 25 A, depending on the capabilities of our multifunction tester) is applied for a period of 60 seconds up to a few minutes and then the resistance is defined by measuring voltage.
• Insulation Resistance Test: This test measures the total resistance of a device's insulation by applying a nominal voltage of 500 VDC to line and neutral conductors and by performing a short in both conductors.

There are of course more complicated Multifunction Testers which can perform many other tests. Some of these tests are described below:

• Leakage Current Test: This test can substitute the Insulation Resistance Test, when the later cannot be performed. The test ensures that the leakage current is low enough so as not to cause any accidents.
• Polarity Test: This test is performed in order to ensure that the active and neutral pins of the plug end are correctly connected to the corresponding terminals at the socket end.

Installation Testers carry out amongst others the following tests:

• Phase Sequence Test: The test ensures that the phase sequence of the incoming line conductors (ie. Brown-L1, Black –L2, Grey-L3) remains the same throughout the installation.
• Loop Impedance Test: Loop impedance test is carried out on a circuit to check the resistance of the live (phase or line) conductor to the earth conductor.
• RCD Tests: The 17th edition of BS 7671 requires that all residual current devices (RCD) either portable or fixed must be electrically tested. There are various RCD tests: RCD Ramp Test, RCD FI Trip Time Test, smooth dc sensitive RCD, etc. which may be supported by a multifunction tester.

Barry Atkins

 

[davenn]

Barry you post is bordering on spam
putting that link in took it over the edge
I have removed the google link


Dave

 

[Barry Atkins]

Hi Dave,

My apologies, I never intended for it to come across as spammy.

I understand why you have removed the link.

Barry