Up to 600 workers face redundancy under plans by Powergen to merge the East Midlands and Midlands Electricity companies.
The jobs are being lost across the Midlands at the enlarged new-look electricity firm - named Central Networks.
Sites affected include Birmingham, Hereford, Telford Northampton, Ludlow, Evesham, and Walsall.
Powergen hopes most redundancies will be voluntary.
The small corporate office at Whittington will also be closed and activities transferred to Powergen's HQ in Coventry.