Three Phase Commericial Application

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I am a licensed electrician in Southern Louisiana. I have done only residential work. I contracted a night club with 15 foot ceilings, to be started in 2 weeks. This job requires 3 phase service, (2) 3 phase 7.5 ton HVAC units, and a single phase supply for lighting. My help (25 years experience, old school and unlicensed) is familuar with this application, but I am not. Could anyone recommend a book on commercial 3 phase application, from service installation to rough-in and trim out. All book publishers welcomed.
 

Strathead

Senior Member
I am a licensed electrician in Southern Louisiana. I have done only residential work. I contracted a night club with 15 foot ceilings, to be started in 2 weeks. This job requires 3 phase service, (2) 3 phase 7.5 ton HVAC units, and a single phase supply for lighting. My help (25 years experience, old school and unlicensed) is familuar with this application, but I am not. Could anyone recommend a book on commercial 3 phase application, from service installation to rough-in and trim out. All book publishers welcomed.
I am not sure what you are worried about, and I am not aware of a book that deals with what you ask.

Not that much to it from the construction direction, much more of an issue from the design aspect. Instead of having phase A, phase B and neutral, which count as 2 current carrying wires, you have Phase A,B,C and neutral which counts as 3 current carrying wires. You treat a single phase load the exact same as you do with 120/240 V, but the applied voltage will be 208 instead, so the equipment has to be sutied for that voltage. Most of it is. A resistive load, like a dryer or a water heater will uses less total wattage, but will also not work as quickly. Typically wire colors are designated Black phase A, Red phase B, and Blue phase C
 

Smart $

Esteemed Member
Location
Ohio
... This job requires 3 phase service, (2) 3 phase 7.5 ton HVAC units, and a single phase supply for lighting...
The lighting may be single phase, but I doubt it needs a [separate] single phase supply.

Your service will likely be 208Y/120V 3? 4W, unless it is a really big project. You can power single phase lighting from this supply either as 208V or 120V. For 208V 1? lighting, you can even connect three equal banks in a delta configuration and power it as a 3? load.
 

kwired

Electron manager
Location
NE Nebraska
You may want to educate yourself fast, or at least have someone else design this for you. If you have 120/208 Y system you will prefer to not have a single phase panel and balance loads across all three phases. If you have 120/240 delta system (which will have one phase with higher voltage to ground (208) then you probably do want a single phase panel as well as a three phase panel, as that high leg will be somewhat limited to what it can be used for. That high leg can also present many other issues for you if you have never been around this kind of system and don't pay close attention to it.

If the service voltage would happen to be 277/480 then you likely have to learn all about properly installing transformers (separately derived systems), and dealing with multiple voltage systems in the same premesis also.
 

cameljoc

Member
Location
South Carolina
Installation Books

Installation Books

Your question about a book, your electrician of 25 years should be a good start. your system should be a 120/208v 3 phase 4 wire system. talk to your HVAC sub and ask him what the voltage on his units are. that along with the kitchen equipment that is being installed. different voltages have different loads and efficiency's.


I am a licensed electrician in Southern Louisiana. I have done only residential work. I contracted a night club with 15 foot ceilings, to be started in 2 weeks. This job requires 3 phase service, (2) 3 phase 7.5 ton HVAC units, and a single phase supply for lighting. My help (25 years experience, old school and unlicensed) is familuar with this application, but I am not. Could anyone recommend a book on commercial 3 phase application, from service installation to rough-in and trim out. All book publishers welcomed.
 

kwired

Electron manager
Location
NE Nebraska
Your question about a book, your electrician of 25 years should be a good start. your system should be a 120/208v 3 phase 4 wire system. talk to your HVAC sub and ask him what the voltage on his units are. that along with the kitchen equipment that is being installed. different voltages have different loads and efficiency's.
120/208 might be what most would prefer. Depending on where this is located you may not have any choice but a delta system with wild leg, unless your customer wants to spend a bunch more money so POCO can upgrade things. So you can't just assume that it will be 120/208.
 
Thank to all.

Thank to all.

I made a call to Entergy yesterday (the provider in New Orleans). They just got back to me an hour ago. They said that the service in that area is 3 phase 4 wire 240v. I am assuming that is a delta (with a high leg). The representative also said that to move to a 120/208 (3 phase 4 wire Wye) system would require a separate pole and different transformer--this is an older commercial area near downtown New Orleans. In addition, she said that the city may not be able to pay for that modification change. She suggested that we meet and discuss the problem with a load calculation, and to tell the HVAC contractor not to purchase any equip until we know which service will be delivered. Again, thanks to all for your help. Note: kwired, good insight.
 
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kwired

Electron manager
Location
NE Nebraska
and to tell the HVAC contractor not to purchase any equip until we know which service will be delivered.
Which is good a good suggestion on any project.

Determine your load needs, then go to POCO and see what you can get, or what it will cost to get what you want and work from there. Old business districts are not always easy to get what you want unless maybe you have extra space available to put POCO equipment on - but often these places have limited space - utilities are usually in rear but back door opens practically right into public alley. They may have huge transformer bank on multiple poles that supplies the whole block and are not willing to do much but connect to what is there. By using a 120/240 delta they can easily supply single phase and three phase customers.
 
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