A new electricity connection is applied for through ESB Networks, usually once you have planning permission. They quote for the connection based on distance and works required, and energisation follows a valid Safe Electric completion certificate.
Apply early. Where the connection requires new poles, a transformer or a wayleave across third-party land, lead times run to many months and can affect the construction programme.
You will need the site location, planning reference and details of the intended load. Quotations are time-limited, and once accepted the works are scheduled by ESB Networks.