Kolkata: As many as 20,000 personnel will be deployed for the counting of votes in the assembly polls in West Bengal on Thursday, an Election Commission official said on Wednesday. "There will be 312 strong rooms, 294 counting halls, 294 counting observers and 90 counting venues across the state," the official said. "The observers have arrived. Around 20,000 personnel will (from both central and state government) be deployed," said additional chief electoral officer Dibyendu Sarkar. Counting begins at 8 a.m. on Thursday and two micro-observers will be present in each hall. "Moreover, one micro-observer will be there at each counting table," he said. Three security cordons would be put in place, he said. "The first is the 100 metre periphery and is called pedestrian zone (no cars). Second cordon begins at the entrance to counting premise and from this layer onwards no mobile is allowed. At this level major frisking will be carried out. The third cordon begins at entrance to counting hall and will be manned by central forces," Sarkar said. As many as 78 companies of central forces will be pressed into service to provide security during counting, he said. "No police personnel are allowed inside counting halls," Sarkar said.