audifanatic
Member
- Location
- Long Island, NY
- Occupation
- Jr. Electrical Engineer
I understand within reason how to size a sub-panel (I deal with commercial buildings, schools specifically). continuous loads vs. non-continuous; heat and air-conditioning won't be running simultaneously, etc.
I would assume sizing a fuse bucket at a distribution panel would be similar. However, since it's commercial, the buckets are feeding other sub-panels (which very well may feed other sub-panels themselves). If any of you have dealt with schools before, they don't maintain anything and a lot of the stuff is original to the building and should be replaced. In my case, the main distribution is from the 1950's and I think it's an old General Electric unit. Many things aren't labeled, if they are, they're scribbled on with a sharpie, and gosh only knows if it's accurate. I could spend a year just tracing everything out. I couldn't imagine what a skyscraper must be like.
Anyway, my scenario is a kitchen renovation. I'm installing a high-temperature dish-washer (it uses no soap, only scalding hot water) that draws 175A. I'm also installing a couple 30A electric hot water boosters (about 30A each). I have no panels that can handle that, so I need to go to the main distribution which is conveniently located in the crawlspace underneath the kitchen.
The client tends to do some work in-house and I happened to catch the electricians one day doing a bus-tap to install a few extra panels. I told them what I planned on doing and I was told "good luck getting anything else in here." The main panel has some empty buckets, but given the statement I received from the in-house electricians, I'm left wondering why would the bus tap been required if there were spare buckets? Maybe my understanding of bus taps isn't fully matured yet.
So I guess my question is two-fold; how to size the bucket without knowing the existing loads and why the need for a tap when there's empty buckets.
Thanks for the help.
I would assume sizing a fuse bucket at a distribution panel would be similar. However, since it's commercial, the buckets are feeding other sub-panels (which very well may feed other sub-panels themselves). If any of you have dealt with schools before, they don't maintain anything and a lot of the stuff is original to the building and should be replaced. In my case, the main distribution is from the 1950's and I think it's an old General Electric unit. Many things aren't labeled, if they are, they're scribbled on with a sharpie, and gosh only knows if it's accurate. I could spend a year just tracing everything out. I couldn't imagine what a skyscraper must be like.
Anyway, my scenario is a kitchen renovation. I'm installing a high-temperature dish-washer (it uses no soap, only scalding hot water) that draws 175A. I'm also installing a couple 30A electric hot water boosters (about 30A each). I have no panels that can handle that, so I need to go to the main distribution which is conveniently located in the crawlspace underneath the kitchen.
The client tends to do some work in-house and I happened to catch the electricians one day doing a bus-tap to install a few extra panels. I told them what I planned on doing and I was told "good luck getting anything else in here." The main panel has some empty buckets, but given the statement I received from the in-house electricians, I'm left wondering why would the bus tap been required if there were spare buckets? Maybe my understanding of bus taps isn't fully matured yet.
So I guess my question is two-fold; how to size the bucket without knowing the existing loads and why the need for a tap when there's empty buckets.
Thanks for the help.
