in Montgomery County and southern Prince George's county you'll see many powerbrackets all over a private property.....and parking lot and all that....in some cases you could see a scene with more than 10 brackets!
in my Area the Powerbracket is Many Times more common than the AEL Ballast in Arm 165.....Nearly all in my Area are Mercury Vapor....a Select Few are HPS and One in another nearby city is the only MH one i know of.