Exhibit 99.1 CERTIFICATION PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002 I, Robert G. Ruhlman, President and Chief Executive Officer, of Preformed Line Products (the "Company"), certify, pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that: 1) The Annual Report on Form 10-K of the Company for the period ended December 31, 2002 which this certification accompanies fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934: and 2) The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company. March 18, 2003 /s/ Robert G. Ruhlman ---------------------------------- Robert G. Ruhlman President and Chief Executive Officer (Principal Executive Officer)