depends on your turnover, previous claims history and number of employees. it also probably depends on the type of work you will be doing. icould be wrong, but I presume if you were doing work in somplace like Intel, it would be more expensive than farm buildings, because of the high cost if claim if anything unfortunate occurred. talks to a broker or insurer
Try and get a quote via reci or ecssa . both have a special deal done with different companies to cover electricians only. full insurance with no claims and no staff €700.00 aprox