More than 30 countries which North America inclusive use voltage of 110V~130V, while another 120 countries
(including most of the European countries) use a voltage of 220V~230V. The electricity in China is generally
220V, 50HZ, AC (Hong Kong is 220V; Taiwan is 110V), while the supply voltage of Japan is 100V, 50/60HZ. If
you visit Shanghai and wish to bring electric devices for use during your stay, a transformer, which can be bought
in China for CNY100 to CNY200. Most of the hotels in China have both of the 110V and 220V electrica outlets in
the bathrooms, though in guest rooms usually only 220V sockets are available.
As the shape of a socket are different between countries, a portable plug adaptor may also be necessary. It can
be purchased from stores (such as Franzus) or electronics stores (i.e. RadioShack, Best Buy) in your local countries.
Also you can buy it in China. Or some of the 5-star or 4-star hotels have the portable plug adaptor available. You
could borrow it from the hotel reception desk.
Here under are the photos of Chinese standard sockets.