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Old 03-21-2008, 09:12 PM   #1
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I am a new login but I have been visiting the site for about a year. So much good info here. I do have a question, I am trying to figure out the size conductors for a 600 AMP service. I do not know all the specs on the building but I do know is is appro 4500 sq ft. I will have a repair garage, 2 apts, and 4 office spaces. The apts are all electric except for heat. And 1 owners panel. I did the service size for parallel 500 with the derating of 30% for 6 conductors in 4# PVC. The amp I come up with is 532. Does this sound right ? Also Only 4 spaces will be condidered continuous. Am I thinking correctly. Thanks for your help.

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Old 03-21-2008, 09:38 PM   #2
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overhead? underground? i'm assuming 1ph by the 6 conductors comment...are you planning on pulling 6 500MCM in 1 4" conduit? i sure hope not...

if you run 2 4" conduits, with 3 500's each, life will be easier and you will be fine...no derating necessary...

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Old 03-21-2008, 09:41 PM   #3
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Single- or Three-phase?
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Old 03-21-2008, 10:11 PM   #4
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first, you need to tell us, are you simply looking for the conductors for a 600 amp service or are you trying to determin if the 6oo amp service is correct.?

Derating for 6 conductors is only 80%, not 70% but as oldman said, I would run 2 pipes but the question comes up, why are you running 500's for a 600 amp service?
you can run paralled 300's (I think) or at the greatest, parraled 350's.

been a while but unless I am mistaken, you can go to the next size standard breaker for a feeders ampacity. Twinned 200's would be 570 amps so I believe it would be alllowable to run a 600 amp service on these.

using the correct size feeders, you could definately reduce the pipe size as well.

a set of 500's is adequate for a 400 amp service. twinned is good for an 800 amp service.
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Old 03-21-2008, 10:21 PM   #5
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nap...i didn't even want to get that deep...my gut feeling is he is over his head and needs someone local with experience to guide him...too much to do over the internet...
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Old 03-21-2008, 10:36 PM   #6
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the fact he is considering running twinned 500's for a 600 amp service defniatelty shows he is in over his head. He is going to cost somebody a lot of extra money that is should not cost.

actually, I had to go back and look. If he is talking about aluminum, he would be pretty close to correct size although he could use 400's instead of 500's but his numbers (derating) would make me believe he is talking copper.

you could be right about the capabilities.
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Old 03-22-2008, 06:21 AM   #7
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Step one - do a service calculation, for each part of the building ( each apartment, each office, garage, and house panel) then for the full service.

Everything else follows from this.
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Old 03-22-2008, 07:35 AM   #8
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First thanks for the help. I was looking at wrong coorrection factor. 20% instead of 30%. Also I am not in over my head I was just looking for a little help and I goes to show when your tired do not try to figure this out. I looked in the wrong place. If I do need help I have other local EC's . But thanks again for the help.
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Old 03-22-2008, 08:07 AM   #9
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Quote:
Originally Posted by Sparks33 View Post
I am a new login but I have been visiting the site for about a year. So much good info here. I do have a question, I am trying to figure out the size conductors for a 600 AMP service. I do not know all the specs on the building but I do know is is appro 4500 sq ft. I will have a repair garage, 2 apts, and 4 office spaces. The apts are all electric except for heat. And 1 owners panel. I did the service size for parallel 500 with the derating of 30% for 6 conductors in 4# PVC. The amp I come up with is 532. Does this sound right ? Also Only 4 spaces will be condidered continuous. Am I thinking correctly. Thanks for your help.
Sparks, with all due respect, I call shennanigins.

Gimme a break, a repair garage, 2 residential apartments, a house panel and 4 "office spaces." I know a service calculation test question when I see one. Do your own homework.

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Old 03-22-2008, 08:31 AM   #10
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As I said in my first post I have not done the load calc yet! I was just looking for a little help with I found. I looked in the wrong place. This is not a test question nor over my head. I thought soming I was figuring did not look right, So I asked for help. When you get answers that some people decide to give it make you wonder if people are just mean spirited. I am man enough to no when I make a mistake or I need a little help. So I am soory I bothered with asking for a little help.
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Old 03-22-2008, 10:24 AM   #11
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Don't get scared away, 33. We're just trying to help you here. No question I've ever seen here is one I would consider stupid, so keep asking!
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Old 03-22-2008, 10:43 AM   #12
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I will not get scared away. I thought I was just asking a legit question.I do know I did not explain everything in detail. This is going to be a single phase going to a 6-gang meter main bank. 4 of the panels are going to be within 10' of the meter. The other 2 witll be roughly 150' ft the meter piped on the outside of the buildin. One of the panel will be thefor the repair facility. Thanks 480 for being the sound of reason.
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Old 03-22-2008, 11:47 AM   #13
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Quote:
Originally Posted by Sparks33 View Post
I will not get scared away. I thought I was just asking a legit question.I do know I did not explain everything in detail. This is going to be a single phase going to a 6-gang meter main bank. 4 of the panels are going to be within 10' of the meter. The other 2 witll be roughly 150' ft the meter piped on the outside of the buildin. One of the panel will be thefor the repair facility. Thanks 480 for being the sound of reason.
Now you have changed everything you ever asked.

Do you want help with the load calcs or the feeders? If you already have the service size, then you are working on feeders.

If you do not have the service size, the feeder size is irrelevent at this time as it is a total unknown.

Now that you have tossed a multipak meter, that changes a lot.

You need to calc each unit individually to determine the overall service.
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Old 03-22-2008, 01:03 PM   #14
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I have not figured out any calcs yet. My main question was if I was fiquring out the service feeder size for a 600 AMP correctly. I had felt that I had missed something. I had looked up the ajustment factor for 4-6 wires but I looked at 30% instead of 20% somebody had pointed out . Now I can figure what size feeders I need to run for a 600 Amp service If this is what I need. Just wanted to know where I went wrong in my calc for the wire size.
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Old 03-22-2008, 01:47 PM   #15
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Here's the problem with your question Sparks:

Quote:
I am a new login but I have been visiting the site for about a year. So much good info here. I do have a question, I am trying to figure out the size conductors for a 600 AMP service. I do not know all the specs on the building but I do know is is appro 4500 sq ft. I will have a repair garage, 2 apts, and 4 office spaces. The apts are all electric except for heat. And 1 owners panel. I did the service size for parallel 500 with the derating of 30% for 6 conductors in 4# PVC. The amp I come up with is 532. Does this sound right ? Also Only 4 spaces will be condidered continuous. Am I thinking correctly. Thanks for your help.
Everything in bold has nothing to do with the answer you seek.
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Old 03-22-2008, 02:01 PM   #16
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you are using copper, correct?

table 310.16

presuming thwn

500mcm is rated for 380 amps. Twice that is 760 amps. I can't remember the section offhand but if you can go to the next standard sized breaker so a double 500mcm would allow an 800 amp service. Due to the derating factor and the difficulty in installation, it is preferred to install in 2 seperate conduits.


300mcm is rated at 285 amps so a double would be 570. Next standard size breaker is 600 amp.

This would be easier to install in one pipe than the 500's but if doing so, you would need to derate to 80%. That would give 456 amps 500 is the next standard size so this is not large enough wire if you need to derate. You would need to upsize to 350's.

310 x 2=620 x .8= 496

whoops still not large enough.

400's

335 x 2=670 x .8=536

Now, you are back to really should use 2 pipes so you can go back to the not-derated ampacity and use 300mcm doubled.

whatever you lose in the cost of the extra pipe, you will more than make up for in the savings in the cost of copper and you will have hair left and skin on your knuckles when you are done.

just a side note: a building of this size and construction will have an architect and engineer making the calls. I would suspect they have the demand already calc'd. That does tend to make this look like homework more than a real life situation. It's not that I have trouble helping with homework but if it is, it is better to let us/me know. I do speak differently to a person that is trying to learn and one that should already know what is being asked but for some reason does not.

Last edited by nap; 03-22-2008 at 02:07 PM.
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Old 03-22-2008, 02:17 PM   #17
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I do understand the mis info I had provided had nothing to do with the sizing it was just a little extra info. I would love to have muilitple conduits but the meter bank only allows for 1 pipe upto 4". All wiring will be copper.
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Old 03-22-2008, 02:32 PM   #18
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can't fit 2 2 1/2 inch pipes in there diagonally?

LB's on the side?



Cost factors would make me look really hard at finding room for a second pipe.

post the manufacturer and model of the meter pak if you can. I find it hard to believe you cannot put more than one pipe in there.
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Old 03-22-2008, 02:52 PM   #19
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It is a Millbank U4376-XT5T9

It can be found at http://www.milbankmfg.com/Products/Catalogs/index.asp

Catalog NEAC 12/04

Found on pg 20 and K.O layout on 21.
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Old 03-22-2008, 03:16 PM   #20
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ok, now you are really sounding like you are a bit lost.

that is a 320 meter, which is essentially a residential 400 amp meter. Previosly you spoke of a 600 amp 6 gang multi meter.

besides, the drawing they show only shows the ko's already there. you can most definately put 2 2 1/2 inch pipes in that line side. the line side section is at least 12 inches wide but since it is only a 320 meter, you would not need the wires we have been speaking of.

scroll down to page 18 and 19 of this site

http://www.milbankmfg.com/Products/C...pdf#multimeter base

You really need to sit down and figure out what you really want and need. As it stands, you are quite confused as to what is happening.

it seems the only meter they have that would fit your specs would be their U2866-X-HSP


Last edited by nap; 03-22-2008 at 03:19 PM.
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