Rv pole with 200 amp outside box. One 30 amp breaker. Ran new wire underground (mobile home type) to small house building in progress. All sockets and lights worked fine up to 2 weeks ago. One overhead light fixture stopped working. Changed to led bulb and it works but flickers. Checked voltage at breaker and it shows 79 volts. Turned all breakers off and removed from both buss bars. One side reads 115. The other reads 89. To ground and neutral same readings. I go back to the pole box it reads 116 on each leg. Changed the light switch for the overhead light but no change. Still will not burn an incandesent bulb but will light an led with flicker. No problems with the other circuits on that leg although they are mostly wall sockets with a few lights. Ideas?