I saw this question earlier, and wrote a lengthy answer for it (offline, as the text editor is not friendly to embedded graphics). When I went to post the answer, the question had disappeared. It had 0 answers at the time. My best efforts to search for it yielded nothing. So I am re-summarizing the question here, and posting my answer.
I am in the Philippines, and I am getting shocked by my shower with electric hot water heater. The Philippine codes are very similar to American NEC. We are getting new 240V service installed.
While we wait, we are using the old service that was present. This provides 220V/240V between only two wires, and does not provide a neutral. I installed a new 8' grounding rod, and measured from the grounding rod to each wire, and got 120V.
The shower is a Panasonic DH-3JL2P. It wants hot, neutral and ground. It is giving me quite a strong shock. Why is it doing this?