240v on 110 leg, bad neutral or ground?

QuestionEdit

I changed an old 100A federal pacific panel at a friends mothers house. The basement had been under a foot of water. there is a lot of corrosion. The panel was reading 230v on one leg and 9 on the other. I was told that light bulbs throughout the house had blown recently. I installed a Square D 100A homeline panel. With no load, the voltages are around 120 to neutral and 240 phase to phase. We put one lightbuld in the basement and it was dim. A second lightbulb brought the first to full strength. a third light bulb made the first too bright. I measured 230v or so and around 9v on the other leg. The ground wire from the panel is grounded to a water pipe, but it is not copper and it switches to pvc after 3 feet inside the house. Could my problem be a bad/open neutral before the panel or maybe its not grounded and i may need a ground rod? Any help would be appreciated

AnswerEdit

If your only ground is to the water pipe then you need a ground rod. You cannot depend on the water pipe to be your ground. Instead, we ground the pipe so it will not be energized. Not the other way around.

Yes, you probably have a bad neutral at or before the panel. If it only happens on this one circuit you may just have a problem with a neutral at that circuit.