Frequently asked questions

Qualified people; specialist advice

  • Height safety
  • Rope access
  • Confined space and rescue

Call Height Dynamics on 07 3862 2533 with your technical questions

Rope Access

What is in a rope access kit?

There is a large variety of equipment that rope access technicians use in their rope access kit. Download our Rope Access Equipment List for an overview.

There you will find items that have become industry standards such as the Petzl ID Descender or the Petzl ASAP Lock through to as well as items that are less commonly used like the ISC D4 or the CT Sparrow.

If you are new to the Rope Access industry training in the correct use of this equipment and the techniques used are mandatory. Further information on our Rope Access training courses can be viewed on our website.

While the Rope Access Equipment List covers the basics it is no substitution for advice from specialist equipment suppliers. Contact Height Dynamics experienced sales team for more information.

Height Safety

Do lanyards need a shock absorber?

To meet AS/NZS 1891.1 2007, which is the standard that fall arrest lanyards are manufactured to, a lanyard must have either integral energy absorbing properties or a personal energy absorber attached to it. The energy absorber is tested to ensure that the force to the anchor point (and user) is no more than 6kN.

Even when using the “restraint technique” to prevent a fall from heights Section 5.2 of the Code of Practise* states that the restraint system (anchor, lanyard and harness) must conform with AS/NZS 1891 Industrial Fall-arrest Systems And Devices series.

*Download a copy of the Managing The Risk Of Falls At Workplaces Code Of Practice 2015 here

What fall arrest harness should I choose? 

compliance level fall arrest harness will have limited or no extra features while a specialty harness will have unique features to meet specific applications or non-standard environments.

To assist with your choice consider the following questions

  • What tasks do you need the harness to perform?
  • How often will you be using your harness?
  • Does the harness fit correctly?
  • What extra features do you require your harness to have?

For more information about fall arrest harnesses refer to our article Choosing a Fall Arrest Harness or contact our technical sales team.

What is the difference between fall arrest and fall restraint?

Simply put a fall arrest system will catch you if you fall, a fall restraint system will stop you from falling in the first place. The “restraint technique” still uses uses fall arrest rated equipment. However, it is used in a way that limits or restrains the user travelling to a position that free fall or fall arrest can occur.

Our article Fall Arrest vs Fall Restraint provides more information on using the "restraint technique"

How do I calculate fall clearance?

When working at height, knowing the required fall clearance is crucial to protecting yourself in case of a fall. The position of the anchor, the length and tear out distance of the fall arrest lanyard and the free fall distance are all factors that must be considered. There are three parts to the equation to work out the fall clearance that is required.Our article What is Fall Clearance provides detailed instructions on how to calculate fall clearance. Alternatively you may want to head to our web based Fall Clearance Calculator and have us do all the calculations for you.

What are the strength requirements for certified fall arrest anchors? 

A certified fall arrest anchor must meet the requirements of AS/NZS 1891.4 and the Work Health and Safety Regulation 2011.

To meet these requirements

  • The rating of the fall arrest anchor must be 15kN (approx 1500kg) for 1 person and 21kN (approx 2100kg) for 2 people.
  • The anchor must withstand this force in all directions in which the force could be applied.
  • A competent person must inspect and approve the anchor point before it is first used.
  • A competent person must assess the strength of the building or structure.

If any doubt exists in the structural adequacy of the anchorage, an engineer must make the assessment.

For more information contact Height Dynamics technical specialists

Confined Space

Gas detector calibration vs Bump test. What’s the difference?

A gas detector calibration is more thorough and confirms the accuracy of gas detection. Bump tests just check the sensor and alarm actually work.

A bump test doesn’t tell you anything about the accuracy of the gas detector’s performance, but it does give you confidence that it is working and is therefore suitable for use.

The gas detector calibration process involves testing the gas detector’s sensors against a known calibration standard (i.e. the contents of your bottle of calibration gas), and adjusting the gas detector to correct for any inaccuracies.

How often should bump tests be carried out?

Best practice for a bump test is daily, and prior to use. Bump testing is the best way to make sure your gas detector actually works before you use it.

How often should gas detectors be calibrated?

Calibration frequencies differ between gas detectors and the manufacturer’s recommendation should be heeded. Height Dynamics calibrate all leading brands. Contact our team if you need help.


How often should refresher training take place?

Competency maintenance is a requirement under the Australian Standard AS/NZS 1891.4. Appendix E4 states that;

"Persons should be reassessed, at appropriate intervals, to confirm ongoing competency relevant to their tasks associated with working in a fall risk environment, in particular persons required to perform emergency rescues need to be reassessed on an annual basis. A person should be retrained whenever they cannot demonstrate ongoing competency. The duration of retraining should be sufficient for the person to demonstrate the required competencies."

Height Dynamics recommendation for refresher training is 2-3 years. For workers not utilising the skills regularly it may be worth having the refresher at 1-2 years to ensure competency.

Our frequently asked questions page attempts to provide answers to common questions our customers are faced with when working at height or in confined spaces.

Naturally, given that workers encounter many height safety scenarios, this list is not exhaustive.

So if your question isn’t answered here, get in touch and someone from our team of height safety specialists will be happy to help.