Equality 7-2521 risked his life to do this. He had a reasonable purpose for doing this. He was very curious about what was in the tunnel and he wanted to help the Council of Scholars. He wanted to install the light bulbs in the world and become a part of the Council itself. The book itself doesn't explain why Equality 7-2521 made this decision so far but we can make some simple assumptions that he wanted to improve the world. In order to do that, he had to go against the rules: you are not allowed to go in restricted areas, you are to do what you have been told, you work for the group and you work for the community, and you obey the rules of the Council of Scholars because they know everything.
People are obligated to do what they are told to, do their assigned job, and obey the Council of Scholars. Ayn Rand is telling us that this dystopia represents the USSR.
Obviously, what happened in chapter seven isn't what Equality 7-2521 expected to happen. "'How dared you think that your mind held greater wisdom than the minds of your brothers? And if the Councils had decreed that you should be a Street Sweeper, how dared you think that you could be of greater use to men than in sweeping the streets?'" (Chapter 7, Rand) They didn't welcome this new science and they found it as some sort of magic or trickery. I think Ayn Rand is trying to show us that this was what happened in Soviet Russia. The Council of Scholars represent the communist government and Equality represents people that have the courage to express their feelings. Ayn Rand expressed her thoughts about communism through this book but the government didn't accept any "unusual" and "daring" thoughts or ideas.