Graybar Electric (GRAYBAR) 10-K 2017 FY Annual report

Exhibit 32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

      I, Kathleen M. Mazzarella, President and Principal Executive Officer of Graybar Electric Company, Inc. (the “Company”), certify, pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, 18 U.S.C. Section 1350, that:

(1) The Annual Report on Form 10-K of the Company for the annual period ended December 31, 2017 (the “Report”) 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.

/s/ KATHLEEN M. MAZZARELLA

Kathleen M. Mazzarella

President, Chief Executive Officer and Principal Executive Officer

March 9, 2018