Sec. 36.121  General.

    (a) The costs of central office equipment are carried in the 
following accounts:

                                                                        
                                                                        
                                                                        
Central Office Switching...............  Account 2210                   
  Analog Electronic Switching..........  Account 2211                   
  Digital Electronic Switching.........  Account 2212                   
  Electro-Mechanical Switching.........  Account 2215                   
Operator Systems.......................  Account 2220                   
Central Office--Transmission...........  Account 2230                   
  Radio Systems........................  Account 2231                   
  Circuit Equipment....................  Account 2232                   
                                                                        

    (b) Records of the cost of central office equipment are usually 
maintained for each study area separately by accounts. However, each 
account frequently includes equipment having more than one use. Also, 
equipment in one account frequently is associated closely with equipment 
in the same building in another account. Therefore, the separations 
procedures for central office equipment have been designed to deal with 
categories of plant rather than with equipment in an account.
    (c) In the separation of the cost of central office equipment among 
the operations, the first step is the assignment of the equipment in 
each study area to categories. The basic method of making this 
assignment is the identification of the equipment assignable to each 
category, and the determination of the cost of the identified equipment 
by analysis of accounting, engineering and other records.
    (1) The cost of common equipment not assigned to a specific 
category, e.g., common power equipment, including emergency power 
equipment, aisle lighting and framework, including distributing frames, 
is distributed among the categories in proportion to the cost of 
equipment, (excluding power equipment not dependent upon common power 
equipment) directly assigned to categories.
    (i) The cost of power equipment used by one category is assigned 
directly to that category, e.g., 130 volt power supply provided for 
circuit equipment. The cost of emergency power equipment protecting only 
power equipment used by one category is also assigned directly to that 
category.
    (ii) Where appropriate, a weighting factor is applied to the cost of 
circuit equipment in distributing the power plant costs not directly 
assigned, in order to reflect the generally greater power use per dollar 
of cost of this equipment.
    (d) The second step is the apportionment of the cost of the 
equipment in each category among the operations through the application 
of appropriate use factors or by direct assignment.