I just had a case where the homeowner was complaining about excessive billing for the 2 years they were in the house. Utility changed out meter once...no change in bills and they told him removed meter was OK. A smoked HVAC fan motor prompted a call to an electrician who discovered a line-to-neutral imbalance of voltage...like 90-130 or so at the moment. Classic open/bad neutral situation although the homeowner hasn't noticed the other symptoms such as dim/bright lights, etc. Electrician contacts the utility who comes out and does a lot of work. Problem solved...bills down to what the homeowner thinks is reasonable. Now, I am told that the typical Form meter used in single phase 3 wire residential applications is non-Blondel compliant and reads all line-neutral usage at 1/2 the current and twice the voltage. Therefore, an imbalance in line voltages will undermeter some loads and overmeter others...the net effect depends on the load distribution and the imbalance. 240 volt loads will always be metered correctly. Anyone ever heard of this effect?
