HVAC & REFRIGERATION SHOW PREVIEW
Many contractors are now turning to complete safe isolation kits, which include all the necessary equipment to safely lock off the circuit being worked on and prove dead.
The latest kits now include matching voltage indicators and proving units and contain a complete range of locking off devices and hazard warning labels for all types of site and installation.
The kits keep everything to hand and simplify any compliance issues with the latest test equipment standards.
Proving dead to stay alive
It should never be assumed that equipment is dead because a particular isolation device has been placed in the OFF position. There are recorded instances where neutrals lines are ‘borrowed’ and while this is not permitted by wiring regulations, it is unfortunately not uncommon.
In this instance, although a particular circuit may be locked off , the neutral conductor can become live if an energised load on another circuit is connected to it. The guidelines require that the circuit be proved dead before any work is carried out.
As Electrical Safety First states, electricians and maintenance teams should use a dedicated voltage indicator and a proving unit when carrying out this procedure of locking off and proving dead.
In line with guidance that a voltage indicator must be able to work without the need for a battery, many voltage indicators, such as the VI13800 and VI-15000, do not require batteries and are dedicated to measuring voltage only, avoiding any potential errors which may occur from using a tester on the wrong setting.
The proving unit is required to prove the correct functioning of the voltage indicator before and after testing that the supply is isolated. Whilst operators can use a known live source to test a voltage indicator is working correctly before and after checking the circuit is dead, it is recommended that a dedicated proving unit is used.
A known live source will only light some of the LEDS on the tester, whereas a matched proving unit will ensure that even the higher voltage LEDs are functioning correctly. Often, there may not be a known live source close by that can be accessed safely.
Fujitsu
www.acr-news.com
December 2017 31
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