Cuino, a good approximation would be to take the 220 volt of the line most loaded by the amperes read with your amperometric clamp, they give you the instantaneous value, in watts, you divide them by 1000 and they are KWH. multiply by the hours of consumption you have the consumption day, week, month, year, whatever, so for each team you should estimate, when you compare it with what the bill says, there will be a difference influenced by the power factor and others seen and hidden consumptions such as driver warming.