The maximum spacing of manholes specified by Indian standard in sewers upto 0.3 m diameter is A. 20 m B. 30 m C. 45 m D. 75 m

The correct answer is A. 20 m.

The Indian Standard IS 4584-1989 (Code

of practice for design and construction of sewerage systems) specifies that the maximum spacing of manholes in sewers up to 0.3 m diameter should be 20 m. This is to ensure that access to the sewer is possible for maintenance and inspection purposes.

Option B is incorrect because it is the maximum spacing for sewers with a diameter of 0.45 m. Option C is incorrect because it is the maximum spacing for sewers with a diameter of 0.6 m. Option D is incorrect because it is the maximum spacing for sewers with a diameter of 0.75 m.