Prior to the aforementioned renovations described in my previous post, my building underwent an electric upgrade. It didn't include rewiring the entire apartment, but rather installing new feeders and a little work on individual wiring circuits. I remained in occupancy as did all the other tenants; it wasn't even proposed that we relocate. Since that time I've seen several apartment rewiring jobs in my building with tenants remaining in occupancy, and on occasions I've had electric work performed related to upgrading wiring in individual rooms all done with me occupying the apt.
The job can be done with you remaining in residence. The LL is entitled to make whatever demands he wants, but in my opinion (I'm not an attorney) it's unsupported by legal precedent in NYC. There's no legal requirement (to the best of my knowledge) for the electric work to proceed; it's a voluntary action on the part of the LL.
It seems to me that the ball is in your court. if you want the upgrade, then accommodate the LL and in accordance to terms that you find agreeable. If the LL won't comply with your terms, then you can refuse the work. If you don't want the upgrade you don't have to meet the LL half way, you can simply refuse the work and refuse to grant access.
If the LL is an argumentative or litigious type and will not take 'no' for an answer, then you can tell him that according to the law there's no legal requirement for the upgrade. Until such a time as he can produce a court decision ordering the electrical renovation in addition to a court decision specifically ordering the work to be performed in your vacated apartment, you will consider the issue closed and will no longer entertain any communication on the topic. Then get on with your life. : )