The two units, bought by Rathmines Chamber of Commerce because they can be safely used by people with no training, were demonstrated at Rathmines yesterday.

"We heard about the St John Project Heartstart and how important it is to have defibrillators on hand if someone collapses and decided that we needed some in the Rathmines community," Chamber vice president Steve Smith said.

St John Regional Manager North, Raelene Tate, said she hoped Rathmines would inspire other small communities to acquire defibrillators.

"These units are incredible. They are self diagnostic, only work if the patient has a genuine heart problem and literally talk the operator through each step. There's a 10 minute window to bring a person back after they have collapsed with heart problems and having one of these units on hand is going to beat the ambulance on most occasions," Ms Tate said.

"We have 350 of these units across the country and we know at least 13 lives have been saved as a direct result."

Mr Smith said one unit would be installed at Macquarie Manufacturing, a metal fabrication company in Immarna Street at Rathmines Industrial Estate.

"The other will be installed at Rathmines Physio in the shopping centre because it is open until 9pm," he said.

Mr Smith said that now the Chamber has the units, a community awareness program would begin.

"We will use a letterbox drop and fridge magnets to let Rathmines residents know where the units are and how to get at them. In the event they can't get to a unit, there will be a telephone number for somebody to get a unit to them," Mr Smith said.

According to St John (NSW), Chief Executive Officer, Sean Gavin, defibrillation is the best chance people have of surviving a sudden cardiac arrest.

"Sudden cardiac arrest (SCA) is Australia's biggest killer, taking the lives of nearly 20,000 people every year. The most successful treatment is defibrillation within a few minutes of the event," Mr Gavin said.

"Defibrillators are the safest and most effective way for people to save lives from sudden cardiac arrest. They are a critical step in the chain of survival. Every minute defibrillation is delayed, a person loses approximately 10 per cent survival chance and that's where these units help."