You can get in the door at 27 but, from the bridge onwards, all enemies will be immune. I did it with my Warlock at that level with WriteThatD0wn and Mazin dragging my sorry ass through it
When I levelled my Warlock, I didn't purchase any of the vendor armour perks as I didn't want to waste the Hadronic Essence. Luckily, that first run through on CE NM netted me the raid boots and helmet. Took about another 10-12 run throughs to get the gauntlets though!
If I remember, you started that raid as a Lvl 27 and ended it as a 30
