OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 33 Explosives Safety

Section 495 Testing detonators and circuits

Subsection 495(1)

Verifying proper operation of the detonator and complete firing circuit ensures that there are no broken wires or short circuits and the resistance of the circuit is compatible with the capacity of the power source. In the event of a misfire, section 509 requires that the worker wait for a period of 10 minutes before approaching the misfire. Doing so prevents the worker from being injured by a slow-to-fire electric detonator. Testing each detonator and its firing circuit detects suspect detonators and avoids the 10-minute waits associated with a misfire.

Subsection 495(2)

Standard ohmmeters or multimeters cannot be used for testing blasting circuits because they can introduce a test current capable of unintentionally and unexpectedly detonating the detonator under test. As written, this section does permit the use of alternate test instruments as long as they are “designed for use with detonators”. Either the product’s manufacturer or a professional engineer can confirm that a particular test instrument is appropriate for use with detonators.