I have a 4000W portable generator I want to use to backfeed my house during power outages. It supports both 120 and 240 output. I know this is a smallish generator so I will turn off all breakers, including the main to the street power, and selectively turn on only the minimum circuits I want to power. I'm familiar with the loads my appliances pull and can manage generator load by selectively powering on different circuits. I wired my detached garage for 240V. I will plug my 240 output into my 240 receptable and let this backfeed to my main house circuit breaker panel. My understanding is this will energize both 120 volt legs of my house breaker panel. Here is my delimma: My generator's 240 output is a NEMA L14-30 receptable which is a 3-pole 4 wire receptacle. My 240 circuit in my garage was wired to operate a 240V electric heater and has a NEMA 6-30 receptacle, which is 2-pole 3 wire. I could make this work by only wiring up the 2 hot les and the neutral between the generator and my 240 wall outlet, except I lose the ability to have a ground fault on the generator trip the breaker. Right? If this is a bad idea then how come it is OK to plug my electric heater into this?