• 100% Satisfaction Guarantee
AssuredElectrical, Master Electrician
Category: Electrical
Satisfied Customers: 4241
Experience:  Contractor-42+ Years in the ElectricalTrade
53189252
AssuredElectrical is online now

# We are working on a datacenter build-out using a 400 amp 480v

### Resolved Question:

We are working on a datacenter build-out using a 400 amp 480v three phase service from the electric company, and would like to know the following:

Is there 400 amps available on each phase?

If using step-down transforms inside of ups's/pdus is the available power once it is stepped down to 120v really 4x the amperage?

For instance 480v @ 400 amps x 3 phases = 1200 amps @ 480v

1200 amps @ 480v x 4 (to go down to 120v) = 4800 amps @ 120v or 2400 amps @ 240v
Submitted: 2 years ago.
Category: Electrical
Expert:  AssuredElectrical replied 2 years ago.

AssuredElectrical :

Welcome. My name is XXXXX XXXXX would be glad to assist.

AssuredElectrical :

The 400 amps, is just that 400 amps. It is not per phase but total. When wiring on 3 phase, you are required to balance the load on each phase so you have uniform phases. But it still equals 400 amps total load If you have 3 phase equipment, it will draw less amperage so each phase is less than it would be if single phase.

AssuredElectrical :

Now, on the 120 volts, if you use transformer to step the voltage down, the 120 volt side will pull 4 times the 480 side approximately. So if you have 100 amps of 120 volt through transformer then the 480 side only sees approx 25 amps.

Customer:

Gotcha, makes sense now

AssuredElectrical :

Using transformers on a higher voltage system allows for a much smaller service than if you had it at 120/240

Customer:

So, on the first question it's just a total load of 400 amps, so you would balance the load and maybe have max ~ 133amps on each phase?

AssuredElectrical :

That is correct. Usually on 3 phase, you have 3 phase equipment connected so pretty much balances itself out.

AssuredElectrical :

Using the transformer for lighting etc, then you get 4 times the power

Customer:

Perfect

Customer:

So would it make sense to use a 250kw generator on this service?

AssuredElectrical :

for 400 amps at 480 volts? generator is 3 phase 480?

Customer:

Ya

Customer:

Looks like from using a calculator it's probably around 300-325 amps @ 480 3 phase depending on power factor

AssuredElectrical :

Ok, the 400 amps at 480 volts is close to 330kw, depends on your power factor.

AssuredElectrical :

Yes, you were writing while I was, lol

Customer:

ok cool :)

AssuredElectrical :

Just Let me know if anything is needed further

Customer:

I think just one more, they will be running it from a CT box from the power company approx. 150 feet to where our main panel will be, what gauge wire would be used for this? and would it make more sense to run it paralleled?

AssuredElectrical :

Only need 4/0 copper , so I do not see any real benefit of trying a parallel feed.

AssuredElectrical :

The length is not an issue with the 480 comes to around 1.3% drop and you are allowed 3%

Customer:

Great, thanks for all of your time, I appreciate it!

AssuredElectrical :

you are most welcome, glad to assist

Customer:

Have a good day!

AssuredElectrical, Master Electrician
Category: Electrical
Satisfied Customers: 4241
Experience: Contractor-42+ Years in the ElectricalTrade

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

### What Customers are Saying:

• You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future. Jimmy Bagley, IA
< Previous | Next >
• You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future. Jimmy Bagley, IA
• Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
• This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
• Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
• I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
• Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
• Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland

• ### Mike

#### Satisfied Customers:

1425
Licensed Master Electrician - OnQ Certified Data Voice Audio Video Installer
< Last | Next >

### Mike

#### Satisfied Customers:

1425
Licensed Master Electrician - OnQ Certified Data Voice Audio Video Installer

### Jason

#### Satisfied Customers:

3871
Over 20 years of experience in all types of installations, troubleshooting, and repairs.

### Mike G.

#### Satisfied Customers:

6511
Proven Professional 46 years Experience

3264

### Kevin

#### Satisfied Customers:

2371
29 years as a Licensed Electrical Contractor in Illinois, 5 year college Electrical Instructor, Former Electrical Inspector, Diploma in Digital Electronics, Former Illinois Licensed Home Inspector

### electrifier

#### Satisfied Customers:

1458
Electrical contractor and electrical inspector for over 24 years with phone and networking expertise