What is the law regarding spotlight/bar light placement on vehicles?

The WA Department of Transport issued a Vehicle Safety and Standards Information Bulletin in August 2015 regarding the use of LED light bars as additional driving lamps. The Australian Design Rules (ADR) 13/00 previously required that additional headlights be fitted in pairs only. This inadvertently prohibited the fitment and use of LED light bars when this later technology became available. Provided they are fitted according to a number of conditions, LED light bars can now be exempted from the original ADR requirement.