I'm working on a project right now; one of the things I needed was a generator cutoff box. This isolates your backup generator power source from other components of the electrical system. When I saw this heavy-duty box with a large, positive throw switch, I thought it would work. I ordered it. When it arrived, I looked it over. There were no surprises; it would do what I wanted it to do. It was made of heavy duty steel and the internals were also solid and clearly labeled. There were good instructions, too. I prepared a generator plug and cord, and then I laid out and screwed down the cutoff box and the electical panel it would attach to. Then, I started wiring it. A bit of a struggle was the knockout plugs; sometimes those can be a pain, and these were no different. The plugs can be many sizes, from small to very large. I needed the small plugs removed for romex connectors. I managed, installed the needed romex connectors, and then I inserted the wires. The box is clearly labeled for LOAD and LINE; where LINE is the power source, and LOAD goes toward the appliances. If you aren't sure how to wire this, you can always call an electrician. After the generator wire was ready, I ran the wire to the small utility box and attached the leads to another circuit breaker; this isolates generator power from the household circuit. It's redundant on purpose. You do not want generator power to backfeed your primary power source; you must keep them separate. This is why, in addition to the very positive large switch on this box, I also put a dedicated circuit breaker in the house box. To power the house buss bar from the generator, you have to choose to close two switches. You cannot power the household buss using your backup generator without closing these switches; therefore, you must also act to isolate grid/other power from the box by opening (turning off) the master power circuit breaker. While you can mess this up, you have to try really hard. Then, I tested the circuit with a multimeter. I closed (turned "on") the big, orange lever on the generator control box, then I closed the 220 breaker on the house box. While my generator is 110, I used a 220 breaker on the household box so that the generator would power both legs of the buss. I tested for continuity between the plug and the buss on the household box; see my attached picture. It works. I tested all components of the system, everything worked as it should. This is a sturdy cutoff box. It is very well-made, and the function couldn't be more obvious or positive. Recommended for electricians or knowledgable homeowners.