Electrical

Electrical Questions? Ask an Electrician Online.

Electrical

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

three phase service from the...
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
Show More
Show Less
9/9/2013
AssuredElectrical, Master Electrician
Category: Electrical
Satisfied Customers: 4,241
Experience: Contractor-42+ Years in the ElectricalTrade
Verified

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: 4,241
Experience: Contractor-42+ Years in the ElectricalTrade
Verified
AssuredElectrical, Master Electrician
Category: Electrical
Satisfied Customers: 4,241
4,241 Satisfied Customers
Experience: Contractor-42+ Years in the ElectricalTrade

AssuredElectrical is online now

A new question is answered every 9 seconds

• Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
• Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.

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.

JimmyBagley, 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!!!!

AlexLos 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.

GPHesperia, CA

I couldn't be more satisfied! This is the site I will always come to when I need a second opinion.

JustinKernersville, 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.

EstherWoodstock, 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.

RobinElkton, Maryland

< Previous | Next >

## Meet the Experts:

Mike

Master Electrician

1,426 satisfied customers

Licensed Master Electrician - OnQ Certified Data Voice Audio Video Installer

Jason

Service Technician

3,942 satisfied customers

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

Mike G.

Master Electrician

7,826 satisfied customers

Proven Professional 48 years Experience

Kevin

3,870 satisfied customers

31 years Licensed Electrical Contractor in Illinois, Adjunct College Electrical Instructor, Former Electrical Inspector, Diploma: Digital Electronics, FCC Technician License

AssuredElectrical

Master Electrician

4,241 satisfied customers

electrifier

Master Electrician

1,458 satisfied customers

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

Rich

Master Electrician

1,115 satisfied customers

Over 35 years residential, commercial, industrial wiring, install, troubleshoot, service, maintain

< Previous | Next >

Related Electrical Questions
My builder hard wired the ceilings for smoke detectors, but
Hi. My builder hard wired the ceilings for smoke detectors, but there is only one white wire and one red wire. What does this mean?I'm trying to install a nest smoke/carbon monoxide detector and it lo… read more
Mike G.
Master Electrician
7,826 satisfied customers
I'm trying to wire a pass & seymour l630p plug with an
I'm trying to wire a pass & seymour l630p plug with an european cord (yellow/green, blue and brown wires), I have the ground wire (the yellow/green) hooked to the proper terminal, but unsure what wire… read more
Mike G.
Master Electrician
7,826 satisfied customers
Bay light has two wire said it is 220 volt how do you wire
bay light has two wire said it is 220 volt how do you wire it … read more
Kevin
Diploma
3,870 satisfied customers
I have three black wires and three wires I don't remember
I have three black wires and three white wires I don't remember how the light switch was wired so far I have capped all three white wires and I found my hot wire but now the outlet next to the light s… read more
Mike G.
Master Electrician
7,826 satisfied customers
I'm trying to wire up a dimmer...I have 2 black wires in the
I'm trying to wire up a dimmer...I have 2 black wires in the box, a green ground and 2 white wires...how do I connect the dimmer? … read more
George Smith
322 satisfied customers
My deep well 220 pump has one wire and 2 identical wires.
My deep well 220 pump has one green wire and 2 identical gray wires. The wires that attach to them are green, red and yellow. I understand green on green but if the red and yellow are both hot does it… read more
Kevin
Diploma
3,870 satisfied customers
I have 3 wires and 3 black wires, and I'm trying to hang a
I have 3 white wires and 3 black wires, and I'm trying to hang a kitchen light I can't seem to get it to work. … read more
Kevin
Diploma
3,870 satisfied customers
I have 2 black wires, 2 capped together wires., and two
I have 2 black wires, 2 capped together white wires., and two copper wires that are tied together but not plugged into anything. We are trying to wire a motion sensor that has 1 black, 1 red, and 1 ye… read more
George Smith
322 satisfied customers
I have a purple wire, a yellow, wire and grey wire and need
I have a purple wire, a yellow, wire and grey wire and need help installing a fan … read more
Sam I
Electrician
B.S.
474 satisfied customers
I need to wire a 2 speed fan ( red, white, and black wire)
I need to wire a 2 speed fan ( red, white, and black wire) to a 6 pin carling or rocker switch that is ON-OFF-ONI want one side of the on to go to the low and the other to the high switch..Can send pi… read more
Mike G.
Master Electrician
7,826 satisfied customers
Fan with light kit white wire, blue wire and black wire. Try
Fan with light kit white wire, blue wire and black wire. Try to connect to three way switch wires to ceiling box are white, red and black. … read more
Sam I
Electrician
B.S.
474 satisfied customers
Need to wire a 240 volt single phase 3 wire motor. Just
the motor has 2 connections for the hot wire and also has a common… read more
Mike G.
Master Electrician
7,826 satisfied customers
I have 3 black wires and 3 wires and 1 coming out of
I have 3 black wires and 3 white wires and 1 white coming out of electrical outlet, how t … read more
Mike G.
Master Electrician
7,826 satisfied customers
I have a sauna that is wired with 240 two wire for load (red
I have a sauna that is wired with 240 two wire for load (red and black) and a ground -- the neutral line (white) is not used -- currently it is not on a GFI and I would like to put it on a GFI - I wou… read more
Mike G.
Master Electrician
7,826 satisfied customers
TROUBLE WIRING A LEVITON 6683. I HAVE ONE HOT WIRE BLACK/
I AM HAVING TROUBLE WIRING A LEVITON 6683. I HAVE ONE HOT WIRE BLACK/ WHITE /GROUND. I AM TRYING TO WIRE 2 /6683 SWITCHES OFF THIS WIRE TO GO TO DIFFERENT LIGHTS … read more
Mike G.
Master Electrician
7,826 satisfied customers
Had broken wire from outside breaker. changed wire to
had broken wire from outside breaker. changed wire to copper. 60 amp breaker trips when power is turned back on. disconnect wire on 60 amp wire and still have voltage in disconnected wire … read more
Mike G.
Master Electrician
7,826 satisfied customers
How do I wire a motion sensor with black and supply wires,
Hi! How do I wire a motion sensor with black and white supply wires, red (or pink) light wires and red, blue and brown sensor wires? Thanks. … read more
Sam I
Electrician
B.S.
474 satisfied customers
Trying to wire a levity 1201-PLR up. Have three wire cable
trying to wire a levity 1201-PLR up. Have three wire cable in box, White, black, neutral. Thought I had it right but light doesn't illuminate … read more
Sam I
Electrician
B.S.
474 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less