Exhibit 23.1 CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM We consent to the incorporation by reference in Registration Statement Nos. 333-106268 and 333-111806 on Form S-3, and in Registration Statement Nos. 33-61093, 333-34433, 333-34435, 333-76138, and 333-76140 on Form S-8, of our report dated January 10, 2005, appearing in this Amendment No.1 to the Annual Report on Form 10-K of Piedmont Natural Gas Company, Inc. for the year ended October 31, 2004. /s/ Deloitte & Touche Charlotte, North Carolina January 24, 2005