Exhibit 23.1 CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM We consent to the incorporation by reference in the following Registration Statements of Cooper Industries, Inc. or Cooper Industries, Ltd. and in each related Prospectus of our reports dated February 18, 2005, with respect to the consolidated financial statements of Cooper Industries, Ltd., Cooper Industries, Ltd. management's assessment of the effectiveness of internal control over financial reporting, and the effectiveness of internal control over financial reporting of Cooper Industries, Ltd., included in this Annual Report (Form 10-K) for the year ended December 31, 2004. No. 2-33-14542 Form S-8 Registration Statement for Cooper Industries, Inc. 1989 Employee Stock Purchase Plan No. 333-02847 Form S-8 Registration Statement for Cooper Industries, Inc. Amended and Restated Directors Stock Plan No. 333-120337 Form S-8 Registration Statement for Cooper Industries, Inc. Amended and Restated Stock Incentive Plan No. 333-24237 Form S-3D Registration Statement for Cooper Industries, Inc. Dividend Reinvestment and Stock Purchase Plan No. 333-101451 Form S-3D Registration Statement for Cooper Industries, Ltd. Dividend Reinvestment and Stock Purchase Plan No. 333-51439 Form S-8 Registration Statement for Cooper Industries, Inc. Director's Retainer Fee Stock Plan No. 333-51441 Form S-8 Registration Statement for Cooper Industries, Inc. Amended and Restated Management Annual Incentive Plan No. 333-37580 Form S-8 Registration Statement for Cooper (UK) Employee Share Purchase Plan /s/ Ernst & Young LLP Houston, Texas February 18, 2005