The company confirmed this morning that its manufacturing division at its site in Bishopstown in Cork is to close.
The facility was set up in the early 1980s and was previously known as Sensormatic, making amongst other things, fire detection products and security tagging devices for shops.
Before the meeting, workers knew there were going to be job losses, but they were not sure of how many - there had been talk of 200 or so redundancies.
Tyco says it will provide severance packages and outplacement services for all 320 being laid off. It will retain only 20 staff in its shared services centre.
The company said that great efforts had been made by employees in Cork to lower operating costs, but it was not enough and manufacturing operations were being moved abroad.
Other branches of the Tyco conglomerate which operate in Ireland are not affected by the job losses.
93 jobs to go at Armagh forklift firm
Almost 100 jobs are to be lost at a forklift truck manufacturing firm in Co Armagh.
The 93 posts are to go at NACCO Materials Handling Group because of falling demand.
The company is the third largest producer of the equipment worldwide and positions will be made redundant over the coming months, with talks now beginning with staff.
Plant manager Alan Little said: 'For the last few months we have seen a significant reduction in demand within the European forklift truck market.'
He said the company was committed to safeguarding as many as is possible of the 712 jobs at the Craigavon plant.
Staff were told the news this morning but management said it had communicated closely with employees over recent months.
Concern for jobs at Kilkenny mine
RTÉ News has learned that unions at Galmoy mines in Co Kilkenny are concerned about possible jobs losses at the site over the next three years.
Meetings are understood to be taking place at the company regarding redundancy payments. Zinc and lead are mined in Galmoy.
The mine is owned by a Canadian company who took over from Arcon a number of years ago.
It is understood the difficulties centre on the high cost of mining zinc and the low selling price for the mineral.
It is believed redundancies are to begin in a few months' time.
