Mystery pipe

I am assuming you want to open the area containing the pipe. There is no other way but to take the risk of taking out selected power and have your contractor be willing to reroute and reconnect it very quickly (they should be able to do it in less than 30 minutes). Naturally you also risk building management being upset.

Also better be sure it is an electrical riser not some other riser like steam.

Just cut it and see who complains. Then you will have your answer.

During one of our combinations, we ran into a pipe of mystery as well. Turned out it was an intercom riser. We had to call in the building engineer, get our building's intercom company involved, schedule a building wide intercom outage, and then the engineer to inspect the final result. (moving it 3 feet and making the accessible behind a small door in the wall) $2,500.00 later, done.

Yes, 300, I should have mentioned--this is directly in the middle of the combined foyer so we want it gone. I think everyone involved is satisfied it's not steam or plumbing of any sort, which leaves electrical, intercom or maybe an old antenna. From what we can tell, the intercom risers are adjacent to the electrical risers in all the apartments, so it probably isn't that.

Selborne, how did you identify what it was? Open it up?

It is no big deal to make a small cut with a handsaw carefully in an electrical pipe and see what is inside.

Thanks. That's what the GC was thinking. I think the electrician was being a bit alarmist, maybe trying to get paid more. He was saying even if we can move it we'd have to rewire whoever's apartment it leads to. Based on my expert googling skills, it seems that code permits you to splice and extend a feeder. I'll follow up when we figure this out.

Just cut into the pipe.(carefully). About 10 pairs of twisted low voltage wires in there.

Exactly and no one needs to know as it is your apartment. Splicing main electrical riser would have been problematic but even that can be done.

I don't understand the lack of basic information from the contractors. The electrician should have a device that can tell whether there is line voltage, low voltage or no voltage in the "pipe" without first cutting it. You describe this as "pipe," but what is it? What is the vintage of the building? Line voltage needs to be run in EMT, not pipe. Low voltage often is not in any sort of conduit. When we gutted our apartment in a circa 1905 building, there were abandoned pipes in the walls from its previous factory history. But there was also a 3" waste riser in a peculiar place unassociated with any plumbing that appeared to originate from the floor drain in the elevator room on the roof. Moving that was no small task, and would have been impossible if we are on a different floor.

Update: the electrician opened it up, it's an electrical riser. Now we need to trace it.

Let us know what process you end up following to move it. Good luck!

It's gone! We were able to trace it to a single apartment two floors above us, and the owner and superintendent were sympathetic to the problem and were fine with us moving the riser. It was traced by getting permission to flip a few neighbors' breakers in the main panel and testing the line voltage. I wasn't there for the party, but it looks like they were able to cut the conduit and put in a turn, rerouting it wire 3 feet horizontally into a wall that we just put up. The junctions are in that wall and the box covers obviously be permanently visible. There will be small a soffit over the entryway to conceal where the line goes back into the ceiling. Could be worse! The contractor was able to dig out enough of the cement that the conduit will sit below the floor level, we don't need a saddle or anything.

That could have been a lot worse.

Congrats! That is awesome. So few people appreciate how difficult it can be to renovate in a building where so much is shared. Your example helps give others some perspective. Thank you for sharing.

Congratulations!! Glad you got the cooperation of the neighbor and super.