Based on what you've told us, it looks like you're covered by the Plumbing and Fire Sprinklers Award [MA000036].
An employee has to be paid public holiday rates for all ordinary time worked on a public holiday.
To calculate public holiday pay rates, use our Pay Calculator.
Minimum hours on public holidays
Regardless of how long they actually work, when a plumbing and mechanical services employee works on a public holiday they have to be paid for a minimum of 4 hours of work at the appropriate rates.
There are no minimum hours that need to be worked on a public holiday for all other employees in this award.
Check the Plumbing Award for the minimum daily hours when working overtime on a public holiday.
Minimum hours on part-day public holidays
Minimum shifts or payments usually mean that an employee is entitled to be paid for a minimum number of hours per shift, even if they don’t work the full shift.
This will usually apply for every time an employee attends work, even if a shift is spread across a public holiday and a non-public holiday.
Substituting public holidays
An employer and an employee can agree to substitute a public holiday (or part-day public holiday) for another day.
If a public holiday is substituted, then the substitute day is regarded as the public holiday and penalty rates are only paid on the substitute day.
Check the Plumbing Award for other entitlements that can apply when working a public holiday.
To find out more about who this award applies to, go to the Plumbing Award summary.
Source reference: Plumbing and Fire Sprinklers Award [MA000036] clauses 14, 32.2, 33.3 and 37