What is the electrical current/voltage in Ireland?

Will I need to pack a converter or plug adapter??

The electrical supply in Ireland is 230v 50hz.

The plugs and sockets are different from the USA involving a three-pronged formation.

The same as those used in the United Kingdom. If your appliances operate on a different current (such as those from North America) you will need a power converter and plug adapter.

Plug adapters do not change the electricity supplied to equipment, they simply allow it to be plugged into a different type of wall socket or outlet. 

All Hotels and most other accommodation in Ireland & the UK will have a two-pin 110v to 120v plug for shavers in the bathroom which will accept an American style plug and allows 120v shavers to run safely. You will require no additional equipment if you are only bringing a shaver.

DO NOT use this power outlet for anything except shavers. It is specifically designed for that one item only and will cause damage to anything else.