Foundation depth is generally light pole height 1/6-1/8, length and width according to your street light lamp type may be, in general, the 600mm-800mm square. , The other should be based on four embedded screws (minimum can not be less than the M20), the screw embedded size is generally 600mm-800mm, do not forget to add embedded PVC casing. As for its overturning resistance, Statistics unto you a year in average wind speed, this can go to the Bureau of Meteorology to check, and then calculate the wind pressure plus a light pole on the light pole itself torque, so you'll know it's the basis of probably should bear the stress, and then down to the actual measurement of the local geological report, will be able to specifically know the street around the foundation required intensity, as how to deal with the most simple is do thirty-seven lime soil.