As far as I know, the normal pronunciation of 栅 as in 栅栏 is zhà, but there is another pronunciation shān listed in dictionaries. Are both pronunciations in common use?
The pronunciation shān is only really used in certain compound words:
光栅/光柵, a diffraction grating used in optics.
栅极/柵極, the grid of a vacuum tube or the gate of a transistor.
Apparently, it also has another pronunciation, cè, for certain placenames in Zhongshan, Guangdong.