How far should a speed camera be placed in relation to the distance from a speed traffic sign?
There is a prosecution guideline that addresses it. I copy the front page and par 1.4 for you.
TECHNICAL COMMITTEE FOR STANDARDS AND PROCEDURES FOR TRAFFIC CONTROL AND TRAFFIC CONTROL EQUIPMENT (TCSP)
Prosecuting Guidelines for Speed Measuring Equipment and Traffic Light Violation Monitoring Equipment
Published: DECEMBER 2012
August 1999 Version 1.1
January 2003 Version 1.2
January 2003 Version 1.3
January 2006 Version 1.4
February 2012 Version 1.5
November 2012 Version 1.6
1.4 Speed Zone Requirements – No prosecution may be instituted where
(i) the speed measurement was taken within 300 meters of the commencement of the speed limit zone.
Alta Swanepoel & Associates