An example of the operation of the first of the exceptions mentioned above would be an exempt orphanage operating a retail store and selling to the general public, where substantially all the work in carrying on such business is performed for the organization by volunteers without compensation. An example of the first part of the second exception, relating to an organization described in section 501(c)(3) or a governmental college or university described in section 511(a)(2)(B), would be a laundry operated by a college for the purpose of laundering dormitory linens and the clothing of students. The latter part of the second exception, dealing with certain sales by local employee associations, will not apply to sales of these items at locations other than the usual place of employment of the employees; therefore sales at such other locations will continue to be treated as unrelated trade or business. The third exception applies to so-called thrift shops operated by a tax-exempt organization where those desiring to benefit such organization contribute old clothes, books, furniture, et cetera, to be sold to the general public with the proceeds going to the exempt organization.
26 C.F.R. §1.513-1