Unexpected high current on 3 ph induction hob.

There are indeed many voltages in the USA, the most common systems are,


3 phase, 4 wire, at 120/208 volts. The norm for smaller business premises and for blocks of apartments.

Single phase, 3 wire, at 120/240 volts. The norm for single family homes.

3 phase, 4 wire at 277/480 volts. Prohibited domestically but popular for industry and larger offices and supermarkets.

3 phase, 4 wire delta, at 120/240 volts with 208 volts between the "high phase" and the neutral. Used to be popular for farms and homes with a largely single phase 120/240 volt demand, but that also need 240 volts three phase for central air conditioning or farm machinery.


The drawback of these systems is the availability of three voltages that are "in the same ball park" but not close enough to be easily interchangeable. 208 volts, 240 volts and 277 volts are all popular.

Small appliances and domestic lighting are virtually always 120 volts. Large domestic appliances such as cookers, water heaters, clothes dryers and the like might be connected to either 120/208 or to 120/240 volt systems. Very few such appliances are made specifically for 208 volts, they are usually listed for operation on either voltage but with reduced performance on 208 volts, and worse still if the nominal 208 volts is actually under 200 volts.

There are indeed many voltages in the USA, the most common systems are,


3 phase, 4 wire, at 120/208 volts. The norm for smaller business premises and for blocks of apartments.

Single phase, 3 wire, at 120/240 volts. The norm for single family homes.

3 phase, 4 wire at 277/480 volts. Prohibited domestically but popular for industry and larger offices and supermarkets.

3 phase, 4 wire delta, at 120/240 volts with 208 volts between the "high phase" and the neutral. Used to be popular for farms and homes with a largely single phase 120/240 volt demand, but that also need 240 volts three phase for central air conditioning or farm machinery.


The drawback of these systems is the availability of three voltages that are "in the same ball park" but not close enough to be easily interchangeable. 208 volts, 240 volts and 277 volts are all popular.

Small appliances and domestic lighting are virtually always 120 volts. Large domestic appliances such as cookers, water heaters, clothes dryers and the like might be connected to either 120/208 or to 120/240 volt systems. Very few such appliances are made specifically for 208 volts, they are usually listed for operation on either voltage but with reduced performance on 208 volts, and worse still if the nominal 208 volts is actually under 200 volts.