You will occasionnally get a slight shock when touching metal on the RV, when plugged in to outlit. I took a Ideal three prong tester and plugged into the storage outlit. The reading came back open ground. I unplugged and started generator. The recepticles inside read correct. I turned generator off and plugged extention card back in. I first checked the outlit again read open ground. I went inside the RV and the reading was correct. I'm asking does this sound OK. Why did the reading inside read correct using the extention cord,when the outlit read open ground. Any help would be appreciated.