The Electrical Code

210.25 Branch Circuits in Buildings with More Than One Occupancy. Here we start by saying that loads being applied to the dwelling will only come from that dwellings panel. So that unit doesn’t pay for other peoples electric bill(I have seen this before). And then part of”B” explains that the smoke alarm and common area lighting can come form the individual dwellings. I thought this was incorrect but this explains it to me that apartments can supply power to those areas directly out side of the apartment. If I have to guess this situation is for less then 3 to 5 apartments in the same building. Personally I have never supplied power coming from a panel that is designated for an apartment to give power to anything outside of that apartment.

This is a good article to know if you were ever to get challenged by a tenant asking why they are paying for anything outside of there dwelling. Number one this a legal practice. Number two anything they do power is minimal power usage. I mean if they supply power to a smoke head, and that smoke head consumes right around 7watts then your paying about $10 dollars per year to be safe. the land lord might specify that into there lease that they are pay for that. But its a small price to pay to keep your neighbors and your family safe.

“(A) Dwelling Unit Branch Circuits. Branch circuits in each dwelling unit shall supply only loads within that dwelling unit or loads associated only with that dwelling unit.

(B) Common Area Branch Circuits. Branch circuits installed for the purpose of lighting, central alarm, signal, communications, or other purposes for public or common areas of a two- family dwelling, a multifamily dwelling, or a multi-occupancy building shall not be supplied from equipment that supplies an individual dwelling unit or tenant space.”