"We found wires that led to strange little globes of glass on the walls; they contained threads of metal thinner than a spider's web." -- Part 3, paragraph 4
This part made me think that the little globes of glass on the wall would be fuses, and I started to think more about the Unmentionable Times. What if the same thing that happened in The Hunger Games happened in Anthem? In The Hunger Games, there is an uprising and District 13 is destroyed. The Hunger Games are created so people remember that the government always wins. Maybe in Anthem, before the Unmentionable times, people had more freedom, and also had better technology (which got destroyed.) Since Equality 7-2521 didn't know the name for the fuse, I think they were used before the Unmentionable Times, and got lost along with other technologies.
"It is cooler in the fields," they said, "and there is water to drink. Are you thirsty?"
"Yes," we answered, "but we cannot cross the hedge."
"We shall bring the water to you," they said. -- Part 4, paragraph (2?)
This book reminds me again of Divergent because the Amity faction works in fields, and factions aren't supposed to go to the other factions or mix with each other. Tris is in Dauntless, but her mom who is in Abnegation comes to talk to her near the fields. A Dauntless man catches them, but her mom is gone before he can do anything. Tris also visits her brother Caleb in Erudite. It is not prohibited, but I could tell that the factions aren't supposed to mix. In Anthem, the rules are more strict. Equality 7-2521 can't even cross the fence of the field, so Liberty 5-3000 has to bring him the water.
As you can see in this image, everyone sits in their own faction, and there is even a quote that states: "Faction before blood."