This article is from the Model Rockets FAQ, by Wolfram von Kiparski with numerous contributions by others.
Both the NAR and Tripoli have HPR safety codes. The two organizations
are working together to produce a consistent safety code to be presented
to the NFPA. These codes specify minimum launch field sizes, minimum
distance to keep from launchers, etc. The NAR High Power Rocket
Safety Code has been published in Sport Rocketry, and is on their web site.
The Tripoli safety code is published in their Members handbook, which is
sent to all new Tripoli members.
EVERYONE WANTING TO GET INVOLVED IN HPR IS STRONGLY URGED TO JOIN ONE OR
BOTH OF THESE ORGANIZATIONS. There are legal restrictions to buying
high power motors. Only certified members of 'legally qualified'
organizations may purchase them. If you want to fly high power you need
to be a member of either the NAR or Tripoli.
The High Power Safety Codes for both the NAR and Tripoli are based on the
NFPA 1127 guidelines. Both organizations recognize the others safety
code, motor certifications, and HPR user certifications.