Re: Emergency Lighting Load for Generator Sizing
For pre-1975 high rises in chicago, you only need em power for the Emergency Lighting. On this particular job, the only way to figure what the lighting load would be, is to get floor plans for every floor and lay it out. There are not floor plans available. The emergency lighting is not all currently fed from the existing em ltg panelboard. They have taken out the em ltg on two floors and replaced it with battery packs. So an amp draw or fixture count will not give me an adequate connected load either. The generator size that we are putting in, is more power than the existing em ltg panelboard is rated for, by quite a bit actually. The reason I asked the question, is that the owner wants to do the job for $12,000. The way we designed it was about $50,000 if I remember the quote correctly. But the $12,000 number was given to him by a contractor who had proposed a much smaller generator. He had also proposed feeding the existing 208v single phase em service with a 240v single phase generator. But all the owner thinks about is the initial quote of $12,000 and how much cheaper it is than reality. So I asked the question of what other people use for a VA/SF basis to size generators based on previous experience. Even for new jobs you can use a VA/SF to get started and then massage it to what actually ends up being connected as the design progresses. That is why it is a useful number.
For pre-1975 high rises in chicago, you only need em power for the Emergency Lighting. On this particular job, the only way to figure what the lighting load would be, is to get floor plans for every floor and lay it out. There are not floor plans available. The emergency lighting is not all currently fed from the existing em ltg panelboard. They have taken out the em ltg on two floors and replaced it with battery packs. So an amp draw or fixture count will not give me an adequate connected load either. The generator size that we are putting in, is more power than the existing em ltg panelboard is rated for, by quite a bit actually. The reason I asked the question, is that the owner wants to do the job for $12,000. The way we designed it was about $50,000 if I remember the quote correctly. But the $12,000 number was given to him by a contractor who had proposed a much smaller generator. He had also proposed feeding the existing 208v single phase em service with a 240v single phase generator. But all the owner thinks about is the initial quote of $12,000 and how much cheaper it is than reality. So I asked the question of what other people use for a VA/SF basis to size generators based on previous experience. Even for new jobs you can use a VA/SF to get started and then massage it to what actually ends up being connected as the design progresses. That is why it is a useful number.