One Leg or Two?
Dear Swami, If a load draws 10 amps at 208 volts, is that 10 amps per leg or 10 amps total?? I recently worked on a show where I calculated 10 amps total and I was shocked to find I was short of amps. Please clarify. Signed, Shorty Dear Shorty, What you have done is a classic miscalculation when you are using 3-phase power. When you connect a 208V load across two legs, you are completing a circuit in which the current is passing through both legs, therefore that would be a total of 20 amps. But something happens when you connect a second 208V load that is not using the same two legs of your 3-phase system. It will also draw 10 amps through both legs, and since one leg will be shared (there is no other option), then the current passing through the shared leg is the combination of the 10 amps being drawn by one of the loads and 10 amps being drawn by the other. The trick is that the currents are 120 degrees out of phase with each other, meaning that the alternating current wavefo...