Pretty simple This shows how switches work (sort of) Here's the system: Switch One turns on. Switch Two only turns on if Switch One is on. If Switch One is turned off when Switch Two is on, Switch Two also turns off. Switch Three only turns on if Switch One and Switch Two are on. If Switch Two is turned off when Switch Three is on, Switch Three turns off. If Switch One is turned off when Switch Two and Switch Three are on, Switch Two and Switch Three turns off.