This article conducts related test verification on the accident cause through an electric cabinet accident. In conclusion, it is important to make good contact between cable lug and bushing in separable connector installation. When the cable lug fails to contact the bushing, the cable lug is overheated, of which temperature reaches 200 times as high as that under well contact, resulting in the product failure and hence accident. Therefore, the article explores a Poke-Yoke separable connection application scheme, preventing ineffective contact and overheating between cable lug and bushing of separable connector caused by various reasons, reducing safety concern during electric power engineering construction.