SHANGHAI, May 30 -- OWNERS of apartments installed with satellite TV dishes should be cautious as Shanghai is entering a season when more lightning strikes can be expected, Shanghai Morning Post reported today.

The metal dishes are perfect conductors of electricity and they have a higher proportion of lightning strikes thanks to their locations – often on the tops of buildings, on surfaces of exterior walls or on balconies.

Shanghai has been identified as a city with frequent lightning strikes as it has an average 49.9 thunderstorm days a year, most of which fall in June, July and August.

Illegal dishes are more dangerous because they usually lack any of the preventive and safety measures against lightning bolts.

"Electrical current from a lightning may reach up to 10,000 amperes while people can absorb 10 milliamperes at the most and still survive," said experts with the Shanghai Meteorological Bureau.

While the bureau couldn't provide detailed figures of injuries to residents or property damage from lightning striking illegal satellite TV dishes.

The city government has banned the production, sale, installation and use of illegal satellite receiving equipment.

But despite the ban, the business has been thriving.

Local residents often receive flyers advertising installation of the dishes with prices varying from around 3,000 yuan (US$392) and more for more channels.

But people from Hong Kong, Taiwan and Macau and foreigners living in Shanghai can apply to local police for a permit to install a dish.