The practices shown in the thread "How many conductors can fit" seem to have once been common.
These two pics are of a typical "in the ground" install at an apartment complex built in the '60's. The heart of the system is a single-gang masonry box, with a 12" nipple of 3/4" RMC exiting the back.
The UF enters the box through the nipple. A concrete block -nicely formed on all sides- completely cases the box and nipple. The box also has a 1/2" plumbing-type "street el" exiting the end of the box, and poking up through the top of the block. The workmanship is so neat and uniform, I can't help but wonder if these things were a manufactured item.
What you see here is a round "Bell" box attached to that street el. Two lampholders were, at one time, attached to the round box.
I say "were", because this entire assembly became buried. A plug cap was screwed into one of the bulb sockets, and buried extension cord was run to a remote light.
At the time I dug this up, the zinc in the Bell box and lampholders was largely corroded away; the lampholders wete corroded completely through at the hinged 'knuckle.' The insulation of the buried extension cord had also completely disappeared- it was not the orange cord you see here- and the three wires were bare, separated only by dirt.
This looks similar to an apt complex I had a call to a while back. After a rain, they called and complained of half the site lighting being out. I found a couple of concrete "pull boxes" similar to this, with old 60's #12 TW made up with regular red wire nuts, simply stubbed from what Im guessing usedto be EMT. Rumor from one of the leasing agents that the maintenance guys used to wire Xmas lights in to that crap come the season!