If my residential rental only has a Certificat of Occupancy for commercial use, is my lease valid?

Do a little bit more digging.  Is your C of O for a manufacturing or other commercial type business?  Then ten to one your apartment is illegal and the lease is not only "voidable" but actually void.  Many landlords have illegally converted apartments in what were commercial manufacturing spaces into lofts for residential use.  This has been in part to a lack of commercial manufacturing business and the buildings being located in an upcoming area close to a major transportation to a large city (Williamsburg Brooklyn comes to mind here).  These situations have resulted in a plus for tenants and a real problem for landlords, because landlord s can not collect rent or utilities from these tenants not evict them or sue for back rent.  So take your case to an attorney in your area and double check your status.  Good luck.

You are facing multiple issues with respect to your rental and lease agreement.  First and foremost, your lease could be voidable because it is not a residential unit and residential leases have certain protections commercial leases do not have.  Further, your landlord cannot simply kick you out in retaliation for discovering what occurred and reporting it to the proper authorities like building and safety and your state or county prosecutor's office.  Most states have slumlord laws so you want to make sure you tap into that avenue in case your landlord's actions equate to such violations.   In terms of electric service, if you did not have an agreement with your landlord to pay the electric service and he failed to get that agreement with you prior to you signing the lease and you were led to believe electric service was included in your lease, he cannot now back bill you.