Define Common Resource Charges

Hi;

We want to define number of machines as Resources in the system and  its depreciation in a way so that it is easy to maintain its cost; for example electricity rate will be same for all machine, if we change cost at one place it should effect on all machines. Please advice how to handle this. This is in the context of charging resources on Job,

Normally we define different machines M1, M2, M3 ... on different routing/operation as it is conversion rate. Issue in this if there is a change than have to change cost in all machines. For maintenance point of view this will be difficult. Electricity charges is one of the example there are more of similar type.