(a) Said City, when engaged in the business of distributing and selling electricity or gas, is hereby authorized and empowered, as part of such business, to engage in the sale, installation, and servicing of such merchandise and equipment as is incidental or auxiliary to the use of electricity or gas or necessary to properly serve the interests of its customers and to promote the sale and use of electricity or gas.

(b) And all acts heretofore done by said City and any of its officers and employees in connection with the sale, installation, or servicing of such merchandise and equipment are hereby confirmed and made valid to the same extent as though this article had then been in effect.