I bought a portable 7000 watt continuous duty generator. It has a floating neutral. I bought a 4 prong L14-30p plug and was going to wire it to the existing underground wire running from a shed where the generator will be to the house. There is a junction box on the outside of the house where the underground wire will be connected to a 8/3 wire with a ground. From there the 8/3 will go to a 200amp manual transfer switch. Whereby when in the up position I'm on pole power, in the middle no power to the house period and in the down position I'll be on generator power. The problem I have is that the buried under ground cable is only 3 conductor, period, no ground. Can I get around this safely or do I need to bury another cable? Any help would be appreciated. Thanks