NSW teachers walk off the job

NSW teachers are set to walk off the job, leaving parents to figure out where their children will spend the day.

About 750,000 students at 2200 public schools and TAFE colleges are expected to be affected as up to 67,000 teachers walk off the job over a 2.5 per cent cap on public sector wages.

Their 24-hour strike action directly defies an 11th hour ruling from NSW Industrial Relations Commission (IRC) judge Frances Backman.

It signals the start of a fresh stoush between the NSW Teachers Federation and the state government, which is threatening to fine the union.

Teachers will join police, firefighters, bus and train drivers, and nurses marching on the NSW Parliament House in what unions promise will be the biggest mass demonstration in two decades.

The public sector workers will be demonstrating against the NSW coalition government's plan to cut 5000 back-office jobs in the public service.

A crowd of 20,000 is expected to gather at the Domain and St Mary's Cathedral, in central Sydney, from 11.30am (AEST) before taking their message against the public sector wage cap and job cuts to Macquarie Street.