DUKE ENERGY CORPORATION EXECUTIVE CASHBALANCE PLAN I & II (As Amended and Restated effective January 1, 1999)

Exhibit 10.18.6

AMENDMENT TO

DUKE ENERGY CORPORATION EXECUTIVE CASH BALANCE PLAN I & II

(As Amended and Restated effective January 1, 1999)

The Duke Energy Corporation Executive Cash Balance Plan I & II (As Amended and Restated effective January 1, 1999) (the “Plan”) is amended, effective as of December 31, 2006, as follows:

“12.5 Transfer of Accounts. The Make-Whole Account and Supplemental Account, if any, of each Spectra Energy Participant maintained under the Plan immediately prior to the Distribution Date shall be transferred to the Spectra Energy Corp Executive Cash Balance Plan and assumed by Spectra Energy Corp as of the Distribution Date. Each such Spectra Energy Participant shall have no further rights under the Plan immediately after his or her Make-Whole Account and Supplemental Account, if any, are transferred to the Spectra Energy Corp Executive Cash Balance Plan and assumed by Spectra Energy Corp in accordance with the terms and conditions of the Employee Matters Agreement by and between Duke Energy Corporation and Spectra Energy Corp (the “Employee Matters Agreement”). Capitalized terms used in this Section 12.5 that are not defined in this Plan shall have the meaning set forth in the Employee Matters Agreement.”

This amendment has been executed by an authorized officer of Duke Energy Corporation on December 19, 2006.