The firm will transfer its Devon arm, which numbers one partner and six lawyers, to Kennedys on Monday (28 July).
RPC managing partner Jonathan Watmough said Tiverton no longer seemed an appropriate base for the firm.
"The lease on the Tiverton building will expire later this year and we had to consider whether concentrating our investment in a regional strategy will provide the best means of serving our clients in the insurance sector, who are increasingly instructing us on more complex matters," said Watmough.
RPC opened its Tiverton office in 2003 after it acquired SJ Cornish & Partners. At the time the firm felt it important to provide its insurance clients with a full service so it needed a high volume insurance claims arm to provide legal advice for both the London market and regional insurance offices.