Measuring amps phase to phase vs neutral and getting odd readings
With Measurements made on loads that have nonlinear characteristics the totals don't always add up the way you would expect. Variable speed motor drives, dimmer circuits, modern flouresent ballast are all devices that can cause interesting voltages and diferent amp draws on each leg. I thought I would also add on a 20 amp electronic furnace I recently worked on when running at low speed had over 9 amp imbalance but at full speed the the imbalance was less than 1 amp. For this reason the NEC considers the neutral to be a current carying conductor with nonlinear loads.