Wonder if anyone would mind helping me size this service. I'm going to have to tell the owner that there's going to be a drastic change in his plans of machinery if my calculations are right. A lot of the machinery he has will have to be changed to 480 volts in order for the existing 120/240 service to handle just a portion of the machines he has. What I have is an existing 120/208 service, which I may have to have the power company to retap to make it 120/240, since his name plates specify 230/460 volts.
I have a 200 amp. 42 cir. 3 phase main breaker panel, with a main lug sub panel fed out of the side of it.(someone else done the existing wiring) There is a 100 amp. breaker ahead of the sub panel.( This is a Seimans "plug in type" ) I have a total of 7 pieces of machinery, with a total of 115 amps.including the 125% for the largest motor My supplier has informed me that the 100amp. breaker is the biggest 3 phase "plug in type" that I can get. The only way I can see that this will work, is that the "authority having jurisdiction" ok it, because some of the motors may not be used at the same time. Is my figuring right so far??
Next the total load on the building consist of: "industrial" application
11,700 sq. ft. X 2 wts./ sq. ft. = 23,400 v/a
Since this is an industrial establishment, according to table 220-11, there is no demand factor that can be applied. It is taken at 100%
I have about (35) 120 volt outlets. If I figure these at 180 v/a I get 6,300 v/a
Since there is no demand factor that can be given to the lighting circuit, I must take these at 100% also.
I have:
(1) 10 hp motor at 230 volts = 28 amps
(1) motor with ? HP = 18.2 amps
(1) more motor with = 18.2 amps
(1) machine with 2 motors
2 hp each (6.8amps/motor) = 13.6 amps
(1) more with the same as above= 13.6 amps
(1) 5 hp motor at 230 volts 15.2 amps
(1) 5 hp motor (same as above) 15.2 amps
Note: all above motors are 3 phase
(1) 3 hp single phase 230volt =17 amps
I have:
2 window a/c and heat units (230 volt
single phase )18.8 x 2 = 37.6 amps
(1) 1.6 hp 115v gas heater motor = 4.4 amps

I get a total of 74848 va / 360 = 207.9 amps
Wonder if this anywhere right, if you care to help? Thanks ..Steve

This is not counting at least 94 amps of other 3 phase machinery he wants to put on this same service. Thanks again for the help. It's been a while since I've had to do these calculations, so I've probably missed something somewhere.

Hi,
There is a big problem with your design..

YOU HAVE NO ROOM FOR FUTURE EXPANSION.

This is required by the code..

Save yourself and your client a lot of time and worry and just install a 400 or 600A service. You will be glad you did!

Now if this is just a practice exercise then it doesnt matter.

Why try to pin it down to the very least? That is not code nor is it good designing.

What will you do if he grows a lot in the next six months and wants to add 5 more machines?


good luck

-regards

greg



[This message has been edited by mustangelectric (edited 03-17-2005).]

I once worked in a machine shop where there were hundreds of machines wired up but we only used 2 or 3 at a time.

You should be able to figure actual demand and size the service for that.

greg, I'm only trying to calculate according to what he already has. I will be adding a 277/480 volt service on the other end of the building to take care of other motors. I just want to make sure that my calculations are right. If this was a new installation, I would definitly put in at least a 400 amp. 120/240 service. That is my point in asking, whether to tell the owner that he will have to change the existing service or not. That will bring up questions also, because he is under the assumption that the service is capable of handling the machines, because someone from the inspection office, ( he assumes ), says that the service is alright. I have my doubts about that though, since I don't think he gave them all the necessary information.
According to what I have come up with on my calculations, I take 125% of the largest motor, and add the total amps of the other motors for the feeder for the sub panel, then for the service size, I take the lighting loads and recept.loads per tables 220-3(a) and table 220-11 and other loads, then divide by 360?? Does this sound right. He has other motors he wanted to put on this service, but the way I see it they will have to be changed to 460 volts and taken out of the other service panel that I am to add, if
he can get by with the minimal machines on the exisiting 120/208 service. Since there are no prints for this job, and there is quiet a bit of confusion between the owner and inspection office, and ME, I'm trying to go the simpliest way and the safest way possible under the circumstances. Like I said, if this was a new installation, I would do it quiet different, but we're trying to make what is available work in as much as possible. As last resort, I may have to tell him that the existing service will have to be changed, but I want to make sure I am telling him right. This is a big expense other than the expense he is already taking.Thanks.. Steve ... Also the 460 volt service was already there on the other end of the building, only the previous owner took the panels with him, and only left the parralled service conductors in a 2 X 2 juncion box. As a matter of note here, he must have disconnected them "hot", seeing that there was still power on the wires. Thankfully he did leave them taped up.... I had to get the local power company to kill the power on them Like I said, I'm preparing for what to tell him ...

[This message has been edited by sparkync (edited 03-17-2005).]

[This message has been edited by sparkync (edited 03-17-2005).]

Hi,
Oh I see...you are trying to calculate the existing load...

thats easy!

get a copy of ALL of his electric bills for the last year or so..

no better way than that!

good luck

greg

Hi,
Geo...you said: "I once worked in a machine shop where there were hundreds of machines wired up but we only used 2 or 3 at a time.
You should be able to figure actual demand and size the service for that."
-----------------------------------------------

can you really calculate a load in a industrial building that has hundreds of peices of equipment that are online by using a couple of them to determine the demand factor and calculate the se load/sizing?

that just doesnt sound right to me. i have never heard of that method...what part of the code is that?

would you use intermittent use or non continuous or what?

just curious..

i always thought you had total up all the defined loads including future expansion?

1600 watts on a 20 amp circuit...thats the max right? so if I have two hundred hair dryers in a salon and they say I only get two cuustomners a day...can i install 2 20a circuits?

what if I have an apartment building that has 200 units...not all of them will be used at the same time...the demand factor is what determines the size fo the service...not everyone will be using the electric range at the same moment BUT the service HAS to be sized for a certain percentage of them being in use..

if i used your method...i could just figure willy nilly that oh say 25 apartments will be cooking at the same time and be within code?

please educate us on this if you dont mind..

-regards

greg

[This message has been edited by mustangelectric (edited 03-17-2005).]

No greg, I'm not trying to figure his electric bill, I'm trying to see if someone can verify that my calculation procedure is right for the load that I described. Thanks

If I understand you clearly you have a 120/208 three phase service at 200 amperes. You are installing a three phase 480/277 service in the plant as well. If the power utility will supply a 120/240 volt delta service then you can run some of the three phase motor load off of the existing panel. Your own calculations indicate that that panel would be over capacity with the loads you already know about and the owner has several more loads he wants supplied. I suspect that you will end up with no motor loads on the 120/208 volt service and that the power company will decline to provide a delta 120/240 volt three phase delta high leg service. If you plan for all of the motors to run at 480 volts; 460 being a nominal rating; then you will only have to size the new service for the motor loads and you can run all of your receptacles and lighting from the existing 120/208 service.

You need the answers to a couple of questions. What size are the existing paralleled service entry conductors on the 480/277 service? Will the POCO provide 120/240 volt high leg delta service? Can the existing panel be used in a high leg delta configuration supply?

Your preferred switch gear supplier can provide a lot of support in verifying your calculations and suggesting ways to deliver the needed power. Keep in mind that every circuit that you can build at the 480/277 voltage will be cheaper to build then delivering the same power at a lower voltage. Your best approach may be to run every motor that can be tapped for it at the 480 volt level.
--
Tom H

mustangelectric ---

Perhaps I misspoke. He should not base the service on the number of machines we used. He should base the service size on the number of machines that the customer will be using at one time. That is usually not hard to do.

And as someone else pointed out using the prior electric bills would give a reasonable estimate of usage.

Hi,
Sparky-There is NO BETTER WAY TO TELL WHAT THE LOAD IS FOR EXISTING INSTALLATIONS THAN A REVIEW OF THE POWER CONSUMPTION over a period of time.

There are tons of ways to calculate the size of a service..

In todays age and time..why even bother with a pencil?

You said: "I'm trying to see if someone can verify that my calculation procedure is right for the load that I described."

No it is incorrect.

good luck..

-regards

greg

Greg, there is no way to get prior electric bills, since this building has been vacant for a long time. I don't even know who the previous owner was. The one who is having the work done, has purchased the building, and is having the wiring done, so he can move his existing business from another location into this one. You said my calculations was wrong. Would you care to educate me a little more? If so, I would appreciate it. If not that's alright too. Thanks Steve

Hi,
First - tell us WHY you want to calculate the existing load?

Second - what will you do with the information?

I did not see any mention of these articles in any of your post..

Start by READING the following articles:

220 Part II
220.3(B)(1) thru (B)(11)
411;215.2(A)(1);230.42(A)(1)
220.4(b); 215.2(A)(1);230.42(A)(1)
220.3(B)(6);215.2(A)(1);230.42(A)(1)
220.3(B)(9); Table 220.13
220.3(B)(9);215.2(A)(1);230.42(A)(1)
220.12(B)
220.3(B)(9); Table 220.13
220.3(B)(8)(1);(2)
215.2(A)(1);230.42(A)(1)
215.2(A)(1);230.42(A)(1)
440.34
440.34;215.2(A)(1);230.42(A)(1)
220.14;430.24
220.21
220.14;430.24
220.35
220.35 Ex.
220.22;310.15(B)(4)(c) To Table 310.16
90.8
------------------------------------------

Finally, find STALLCUPS ELECTRICAL DESIGN BOOK and BUY it! There is hardly ANY better reference out there that I know of. I use it EVERYDAY.

I will chew on your list and get back to you.

Thats about the best I can do right now.

DO NOT GET IN A RUSH!

-regards

greg

[This message has been edited by mustangelectric (edited 03-17-2005).]

Thank you Tom for your reply.
In past conversation with the power company, I don't think they will provide the 120/240 delta. As far as the conductors in the previous 277/480 service, they are 3/0 parralled. I intended on installing a 400 amp. main breaker panel back in this location. We are trying to get as many of the motor loads as possible on the 277/480 volt service. Right now not counting the motors I described in my original post, I will have probably (14) 3 phase motors coming off of the 277/480 volt service if possible. That will be 42 circuit panel. (Just now realized that.) I have calculated the estimated amps. as 170.8 amps. I know that would give me ample room to add the other ones probably (as far as amps that is) , but then I now realize I will have to set a sub panel coming off of this one, for future expansion, but some of the motors are not convertible according to the nameplate, and also they are already piped into the 120/208 panel. The 277/480 panel will be a long way off from the locations of these machines also. The other machines I am planning on taking to the 277/480 panel will not be that far from it. The machines that I do plan to tell him that we will have to convert to 460, unless we change the existing 120/208 200 amp. service, may or may not even be able to be converted. Most of the machines are not present in the building at this time, and I am having to go back and forth to get the information I need. When most of the necessary wiring is done, he is planning to move his machines at that time, and do the rest of the "hook ups" etc. He cannot afford to shut down his existing business now to move the machines into the new plant. Hope this helps explain things a little more.. Thanks again for your help. Steve

[This message has been edited by sparkync (edited 03-17-2005).]

Hi sparkync,

It is not a good idea to apply 220.?? demand factors in an industrial environment. As most business owners want to see their business go and will do anything to ensure it's growth, there will be a time when all machines will be operating at the same time.

Also, 180VA per receptacle at 100% is okay for normal use. However, you should also take into account if they have any drill presses or bench grinders, etc. plugged into a receptacle and add those device's load at 100% to the receptacle load.

Additionally, is the general lighting load a 2VA per sq.ft. a reality in this shop? Are you going to add additional lighting that 2VA per sq.ft did not cover?

If the building has a office then the use of NEC 220.?? is good, other than that, I'd stick to 100% load for the working side of the building.

[This message has been edited by DiverDan (edited 03-17-2005).]

Thank you also Dan for your input,
The 2 watts/sq. ft. might not come into play with all his facility, being that for now, a large portion may be considered storage, which would only calculate at 1/4 wt./sq. ft., but I went ahead and figured it at 2, because of the very fact you said. In a shop like this, he will be wide open to put out orders etc., and I'm sure he'll be using it also for production machinery. My general calculations were that I would figure everything at 100%. I was wanting to make sure before I broke the bad news to him, that I was figuring right. My main question I guess was that according to the calculations I done above, if correct, there is absolutely no more room for machine loads on the existing 120/208 200 amp. service with my calculations being in the minimum of 207 amps. And yes, he already has floor fans setting around, a welder, and who knows what else might be there, once he moves in. That's my next decision before I can do more work, is to break the bad news to him, that the existing service will have to be changed to at least 400 amp., to take care of all the machinery he is expecting to use. I just needed some other verification that I was right.... Thanks again for the input.. Steve

Hi,

Dan- You said: "It is not a good idea to apply 220.?? demand factors in an industrial environment."

What?

There is NO way you can correctly calculate the SE WITHOUT applying article 220 and remain within the NEC. (PERIOD)

No offense dan but what on earth gives you that idea?

do you see the list of articles I posted above? each one of those covers INDUSTRIAL applications..you can ignore them if you want to..

if you do your calculation wont be worth the paper you wrote it on.

I will let you guys handle this! Im out!

-regards

Greg



[This message has been edited by mustangelectric (edited 03-17-2005).]

You're right Greg, its late and I'm also tired...so I won't bother with your overly simplified response either. By the way. a Demand Factor is a derating factor and the working side of an industrial environment should not have any applied deman factors (derating). PERIOD! If you think it does then you have never been involved with any format of large or small manufacturing. PERIOD!

I guess I should say something else about NEC 220.??. As you all know, these are application specific "general" branch circuit and service sizing methods, kind of like "black box" engineering. As such, most EE's and Design Engineers do not and will never use them as a valid means of circuit or service sizing. They only use specific device characteristics inconjuction with continuous - non-continuous load factors to size the circuit and service for final presentation. It was with alot of controversy that we included them in Volts. But since many electricans requested their inclusion...we included them.

Greg I got here late but can you explain what you mean by this?


There is no requirement in the NEC to size a service for future expansion.



It is right in article 220




What part of the code says that?

120 x 20 = 2400 watts.

We can load a 20 amp circuit to 20 amps (2400 watts) if it is non-continuous.

If it is a continuous load (on for more than 3 hours at a time) we can only load to 80%.

120 x 20 = 2400 x .8 = 1920 watts.

One last thing Greg, using all capitols is considered shouting and rude.

You are coming on very strong in this thread when IMO you should be asking more questions.

If you are going to say something is 'code' get out the book and tell us the code section you are referring to. That 'laundry' list of code sections you posted does not help.

Thanks, Bob




[This message has been edited by iwire (edited 03-18-2005).]

Hi,
Like I said there is NO WAY to properly calculate the LOADS in a INDUSTRIAL environment without using the following articles:

220 Part II
220.3(B)(1) thru (B)(11)
411;215.2(A)(1);230.42(A)(1)
220.4(b); 215.2(A)(1);230.42(A)(1)
220.3(B)(6);215.2(A)(1);230.42(A)(1)
220.3(B)(9); Table 220.13
220.3(B)(9);215.2(A)(1);230.42(A)(1)
220.12(B)
220.3(B)(9); Table 220.13
220.3(B)(8)(1);(2)
215.2(A)(1);230.42(A)(1)
215.2(A)(1);230.42(A)(1)
440.34
440.34;215.2(A)(1);230.42(A)(1)
220.14;430.24
220.21
220.14;430.24
220.35
220.35 Ex.
220.22;310.15(B)(4)(c) To Table 310.16
90.8
------------------------------------------

that said, anybody that doesnt agree is certainly entitled to disagree. Myself I will stick with Stallcup before I listen to any of the advice that has been posted in this thread.

just for the sake of arguing:

someone said: "By the way. a Demand Factor is a derating factor and the working side of an industrial environment should not have any applied deman factors (derating). PERIOD! If you think it does then you have never been involved with any format of large or small manufacturing. PERIOD!"

you also said: "As you all know, these are application specific "general" branch circuit and service sizing methods, kind of like "black box" engineering. As such, most EE's and Design Engineers do not and will never use them as a valid means of circuit or service sizing."

my response to that? You are a dangerous person and have NO business even being involved with the electrical trade. your comments are ridiculous and nothing more than an attack, this was a discussion, now it is nothing more than a pissing match with someone who OBVIOUSLY doesnt have a clue so I will not even respond to anymore of your comments.--

ANYONE who says that providing room for future expansion IS NOT part of the code is obviously not very knowledgeable in regards to the code and doing electrical work...you are the kind of guy who will go out and installa 32 circuit panel and fill it up and leave no spaces for anything in the future..there are PLENTY of sections in the code that require this...I suggest you either take a course or start all over and go back to sqaure one..i would love to see some of your work..it probably would wind up over there at the "whats wrong with this picture" pages..

if you want to load a 20A circuit to 2400VA go right ahead..once again there are several other articles in the code that would not agree with that...myself, I call it riduclous and DANGEROUS.

someone also said: "One last thing Greg, using all capitols is considered shouting and rude."

my response: that is YOUR opinion...the truth? if I used ALL CAPITALS LETTERS LIKE THIS THEN I AM SHOUTING AT YOU! GET REAL! I was simply EMPHASIZING AND STRESSING THE WORD! your kinda touchy aint ya? have a bad day or what?

someone said: "You are coming on very strong in this thread when IMO you should be asking more questions." I do ask questions...when I want to know the answer to something I dont already know. but thanks for being so friendly!

another ridiculos statement: "That 'laundry' list of code sections you posted does not help."

well i guess James Stallcup is an idiot too and knows nothing about the code?

becasue that laundry list of articles that does not help came from JAMES STALLCUPS "DESIGNING ELECTRICAL SYSTEMS" LOOK IT UP! LOOK at Stallcups electrical design book and go to "SIZING INDUSTRIAL LOADS" after you do that go tell James that he wasted his time printing millions of books and spending millions of dollars putting ou that USELESS information! MAN! some poeple!

I will stick with stallcup.

so now that I have responded to all of these ridiculos comments and attacks, I will bow out of this thread and let the "EXPERTS' have their way.

My sincere apologies if anyone got offended, sometimes the written word doesnt carry the same meaning as the spoken word so forgive me if anyone got upset.

TAKE TWO AND THINK IT THROUGH!

-regards


Greg

Greg,
Unless the bill includes a demad factor, the everything is operated 24/7 a bill does not help you calculate loads.
Don

Hi,

Don- have you ever seen a commercial/industrial power bill? do they not include the demand factor?

and i guess they dont meter power 24/7.

i know for my shop it does.

anyway to make everybody happy---

-"Do not use an electric bill to see what kind of load/power a place may be consuming."

use the methods posted by sparkync,George,DiverDan,iwire,resqcapt19 and anybody else that knows.

hey maybe i mispelled some words too..anybody care to take a shot?

nothing personal on my part guys..

thanks for the comments.

-regards

greg

[This message has been edited by mustangelectric (edited 03-18-2005).]

Thanks for the comments, all. I informed the owner we will have to change his service to do what he wants.... Steve .... end of thread....

Greg it is nothing personal here, it is all about the trade. Don is just as likely to point out when I am wrong as anyone else. I do not take it personal.

The reason you are getting singled out is because you post stuff like this...


...then when asked about it you say nothing.

This section of ECN is called "NEC & other Code issues" as such we try to provide code references.

Please do not take things personal.

Bob

mustang,
Please read article 90.1(B). You may want to retract this statement: "There is a big problem with your design..
YOU HAVE NO ROOM FOR FUTURE EXPANSION.

This is required by the code.."