EXHIBIT 23.01 CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM We hereby consent to the incorporation by reference in the Registration Statement on Form S-8 (No. 333-91187) of WESCO International, Inc. of our report dated May 14, 2004 relating to the financial statements of the WESCO Distribution, Inc. Retirement Savings Plan, which appears in this Form 11-K. Pittsburgh, PA June 28, 2004