How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask AssuredElectrical Your Own Question

AssuredElectrical
AssuredElectrical, Master Electrician
Category: Electrical
Satisfied Customers: 3346
Experience:  Contractor-40 Years in the ElectricalTrade
53189252
Type Your Electrical Question Here...
AssuredElectrical is online now
A new question is answered every 9 seconds

Electrical build out question - allowed amps wired up vs incoming

Resolved Question:

Electrical build out question - allowed amps wired up vs incoming amps

Hi, I'm working on a project that involves a lot of power and a lot of drops of electrical wiring for servers, etc.

If we have say 600 amps(208 three-phase) coming into a building, are we limited on how much we can build out in outlets?

I was told we wouldn't be allowed to have more than 10% overage of 30-amp 208v drops because of the incoming amps. So if we get a bunch of 30-amp 208v three phase drops in place, but we're only planning to use 21 of those amps on each, we can't actually max out our 600 amps coming into the building because (by code) we won't be allowed to put in the extra drops necessary to make up the difference. Is this correct?

(Another way to explain my question... 600 amps 3-phase is 215 kW coming in. 35 drops of 30a-208v @ 6.2kW each would use all that power. Would we be allowed by code to put in 60 drops if our plan was to under-utilize those circuits?)

We are located in central Washington state if that changes anything.

Thanks,
Jared
Submitted: 1 year ago.
Category: Electrical
Expert:  AssuredElectrical replied 1 year ago.
Welcome. My name is XXXXX XXXXX would be glad to assist.

To determine if the service is adequate for any additional build out, one must first know the complete electrical as it is now.

The buildings purpose and square footage, the heating and air conditioning loads(sizes and amperage), any other existing equipment in the building (sizes and amperage).
Once you have the total need determined, then you can see what is available for future expansion.


Is all this information available?

Thanks
Customer: replied 1 year ago.

For now assume the other stuff is negligible. We have less than 2 kW of lights running, heating will be disconnected, A/C will be run by us(and we can account for those loads, but just hypothetically assume we have 2 60a 208v circuits dedicated to A/C. There's nothing else in the building except a garage door opener that might pull 2kW at max(but I doubt it).


 


What level of 30amp circuits would we be allowed to add?


 


Thanks, Jared

Expert:  AssuredElectrical replied 1 year ago.
Ok, thanks.

On these "drops" at 6.2kw, how long are they operating per day?
What is the actual load being served?

Are all the drops operating the same amount of time?
Customer: replied 1 year ago.

24/7, actual load is somewhere between 12 and 26 amps.


 


Yes, most but not all drops are active at the same time.


 


I can easily calculate out what we can run on our incoming 600 amps. What I'm trying to figure out is what code allows us to build because we may be in a situation where we need more drops but put less load on each one as time goes on, but if we don't build for it up-front it is more expensive to add it later.


 


Jared

Expert:  AssuredElectrical replied 1 year ago.

Ok, thanks.

When you have equipment such as this operating in an almost continuous manner, you calculate it at 125%.

So, the number for the service load calculation goes up at 6.2 x 125%= 7.75kw

With just guesstimate of AC and lighting, you probably have 20kw.

Leaves you with 195kw at most (not counting anything else in the building)

So, you could have 25 drops of your maximum.

You have to calculate at the maximum usage point that the equipment is capable of operating at any point in time.

Just like on a stove, the entire stove is 6000 watts even though you rarely use it all, only a small portion is normally operated.

But it is capable of the total, so it must be accounted for in the calculation..


Any other electrical will take away from that number as well. Like water heating, outdoor lighting, convenience receptacles, other lighting or more AC needs for heat dissipation etc.

Customer: replied 1 year ago.

Ok, but what does the code allow? What if the maximum load we expected from one device was 12 amps / 2.5kW, would we be able to run more and still meet WA electrical code?

Expert:  AssuredElectrical replied 1 year ago.

It is based on what is in place, not what is expected, but what it is capable of consuming

So, if you have half of your posted 6.2kw in place for operation, then you would have double the amount available, once all existing electrical is accounted for and calculated

That is why it is critical to know what the equipment nameplates state as the wattage.
That is what must be used for the determination.

 

If there is no equipment in place, you can place the drops for possible future movement of equipment. If there is nothing there to operate, there is no load at the time.

Just specify each drop at 2.5kw for your installation.

 


That is the NEC.

Customer: replied 1 year ago.

So so long as we have nothing there at the time of inspection, we can run whatever we want?


 


The reason I am asking is we want to run extra drops to accommodate future possible needs, with full knowledge that plugging in all of them could run us over limits and cause the main breaker to blow. We just can't perfectly anticipate our future needs, but we were told (by a non-electrician) that code only allows for a 10% net overage.


 


Thanks,


Jared

Expert:  AssuredElectrical replied 1 year ago.
Ok, I understand a bit more on the drop situation now. Not all in use and unsure exact needs in the future etc. Makes sense.

The key will be what the drops are specified for, in the permitting portion.

Specify the lowest KW per drop you anticipate in order to get the drops in your various locations. That will keep you from encroaching any limitations.

Or, if you have them calculate the feeder to the various locations in anticipation of future drops, the proper wire size will be installed to all the locations and drops can be added at any point along the way.
Similar to what is done on an assembly line, the feeder runs the entire length but drops are only installed at various points as needed until a later time.

Remember, The entire building will have to be calculated as it is now before any definitive numbers can be determined. So it can change for better or worse on what is available for the drop installations.

Not sure what this 10% overage is about.
You calculate the total needed in loads, existing and new installations added together.
The total KW.
AssuredElectrical, Master Electrician
Category: Electrical
Satisfied Customers: 3346
Experience: Contractor-40 Years in the ElectricalTrade
AssuredElectrical and 5 other Electrical Specialists are ready to help you

JustAnswer in the News:

 
 
 
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.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...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
< Last | 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
 
 
 

Meet The Experts:

 
 
 
  • Mike

    Master Electrician

    Satisfied Customers:

    1425
    Licensed Master Electrician - OnQ Certified Data Voice Audio Video Installer
< Last | Next >
  • http://ww2.justanswer.com/uploads/mikepettinato/2009-9-4_41145_DSC005132.jpg Mike's Avatar

    Mike

    Master Electrician

    Satisfied Customers:

    1425
    Licensed Master Electrician - OnQ Certified Data Voice Audio Video Installer
  • http://ww2.justanswer.com/uploads/WI/WireitUp/2012-6-17_18212_Photo00006.64x64.jpg Jason's Avatar

    Jason

    Service Technician

    Satisfied Customers:

    3278
    Over 15 years of experience in all types of installations, troubleshooting, and repairs.
  • http://ww2.justanswer.com/uploads/MI/MikeG2010/2012-6-7_192640_IMG01612.64x64.jpg Mike G.'s Avatar

    Mike G.

    Master Electrician

    Satisfied Customers:

    5318
    Proven Professional 45 years Experience
  • http://ww2.justanswer.com/uploads/AS/AssuredElectrical/2011-9-13_221243_me.64x64.gif AssuredElectrical's Avatar

    AssuredElectrical

    Master Electrician

    Satisfied Customers:

    2149
    Contractor-40 Years in the ElectricalTrade
  • http://ww2.justanswer.com/uploads/electrifier/2008-12-16_200429_headbob1.jpg electrifier's Avatar

    electrifier

    Master Electrician

    Satisfied Customers:

    1454
    Electrical contractor and electrical inspector for over 24 years with phone and networking expertise
  • http://ww2.justanswer.com/uploads/rich03dungo/2010-3-17_101556_tshirt2.jpg Rich's Avatar

    Rich

    Master Electrician

    Satisfied Customers:

    1115
    Over 35 years residential, commercial, industrial wiring, install, troubleshoot, service, maintain
  • http://ww2.justanswer.com/uploads/UR/urelectrician/2012-9-28_223652_JustAnswerPic.64x64.jpg Kevin's Avatar

    Kevin

    Licensed Electrician

    Satisfied Customers:

    993
    27 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
 
 
 
Chat Now With An Electrician
AssuredElectrical
AssuredElectrical
Electrical Contractor
2574 Satisfied Customers
Contractor-40 Years in the ElectricalTrade