When and why should I start to use height safety equipment? What is considered as working at height?

The Work at Height Regulations 2005 (UK) defines it as:

“Work in any place, including a place above, at or below ground level; obtaining access to or egress from such place while at work, except by a staircase in a permanent workplace; where, if measures required by these Regulations were not taken, a person could fall a distance liable to cause personal injury;”

You should follow the hierarchy of safety when planning, managing or completing work at height. Where possible AVOID work at height by utilising alternative methods and work practices. 

Where it cannot be avoided you should PREVENT falls by carrying out the work from an existing place of safety or utilising methods and equipment which will prevent falls. As a last resort MINIMISE the distance and consequences of a fall, by using the right type of fall arrest equipment (where the risk cannot be eliminated).

Your fall protection equipment could KILL YOU if you DO NOT know how to USE IT correctly. Please always refer to the manufacturers' user Instructions and ensure you are trained in its use."