You are on a service call in which two 500/1000 watt heaters are plugged into a 120 volt bedroom circuit and are sometimes tripping the circuit breaker. The heaters have low and high settings, and on low they each draw 500 watts. The home owner complains that he wants the heaters to function when set on the high setting, which is the full 1000 watts for each one. The circuit is 15 amp rated. What is the cause and what is the most reasonable and safe recommendation