# 3000 amp service



## erics37

Sorry we don't have direct access to your hard drive :laughing:


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## Vintage Sounds

You need this thread.


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## wjcarty10

thanks for your help man.. as you could tell im not the best with computers


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## erics37

wjcarty10 said:


> thanks for your help man.. as you could tell im not the best with computers


Looks like a bitchin' project!


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## HARRY304E

wjcarty10 said:


>


Good stuff..:thumbup:

Welcome to ET..:thumbsup:


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## Vintage Sounds

Now we're talking. That looks awesome!


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## BBQ

It looks great and it is fun work. 

Next time you might want to consider doing it like this, it saves a lot of chris crossing














> 300.3(B)(1)Exception: Conductors installed in nonmetallic raceways
> run underground shall be permitted to be arranged as isolated
> phase installations. The raceways shall be installed in
> close proximity, and the conductors shall comply with the
> provisions of 300.20(B).


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## EBFD6

Should have used MC, it's cheaper.


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## Big John

EBFD6 said:


> Should have used MC, it's cheaper.


 :lol:

Do you have rigid sweeps or something in that run? Otherwise, I agree, separate out the phases can make termination a lot easier.

You guys use Simpull for all your large runs? Looks good.


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## EBFD6

Big John said:


> You guys use Simpull for all your large runs?


IMO, there's no other way. That stuff is awesome.

Colored wire is also a huge time and mistake saver. It's especially nice when the whole pull comes on 1 reel with the pre-made crimped pulling head. Just hook it up and go. With the tuggers and wire feeders we have now it hardly feels like work anymore.


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## ponyboy

BBQ said:


> It looks great and it is fun work.
> 
> Next time you might want to consider doing it like this, it saves a lot of chris crossing


Is that the only exception to allow this or are there more? My books outside


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## BBQ

ponyboy said:


> Is that the only exception to allow this or are there more? My books outside


Get off your butt and walk outside. :jester:






As far as I can remeber that is the only one.


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## erics37

BBQ said:


> It looks great and it is fun work.
> 
> Next time you might want to consider doing it like this, it saves a lot of chris crossing
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 300.3(B)(1)Exception: Conductors installed in nonmetallic raceways
> run underground shall be permitted to be arranged as isolated
> phase installations. The raceways shall be installed in
> close proximity, and the conductors shall comply with the
> provisions of 300.20(B).
Click to expand...

That is what I would call a preemptive code reference :laughing:


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## farlsincharge

I don't think that installation would be legal here, but if I had to do something with 8 parallel sets I would be looking into it pretty hard.


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## Deep Cover

Looking at these pics brings up a conversation we have been having at work. What is an acceptable difference in length between parallel conductors? Ideally we would like them exact, but do you pull off the conductors from the reel and measure each one out? Or do you take the supply house's word for it?


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## erics37

farlsincharge said:


> I don't think that installation would be legal here, but if I had to do something with 8 parallel sets I would be looking into it pretty hard.


I think it's a good code allowance. The requirements referenced in the code article BBQ posted basically say to avoid running your conduits and conductors in such a manner as to prevent inductive heating of metal enclosures and such. Would be a moot point in an open-bottom piece of equipment.

I like saying open-bottom.


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## EBFD6

Deep Cover said:


> Looking at these pics brings up a conversation we have been having at work. What is an acceptable difference in length between parallel conductors? Ideally we would like them exact, but do you pull off the conductors from the reel and measure each one out? Or do you take the supply house's word for it?


If the conduits are routed the same way, and the wires take the same route to the terminations once they exit the conduits, your lengths are going to be close enough. A variance of a few inches from conductor to conductor isn't going to be an issue. If they are off by a few feet you may have a problem.


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## ponyboy

BBQ said:


> Get off your butt and walk outside. :jester:
> 
> As far as I can remeber that is the only one.


Haha thanks. For some reason I thought it only worked with four or eight parallel sets not sure why. It's good to know that exceptions out there but every time I remember it exists I kick myself for all the massive services I neglected to use it on


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## Big John

Deep Cover said:


> ...Ideally we would like them exact, but do you pull off the conductors from the reel and measure each one out? Or do you take the supply house's word for it?


 Maybe there's a more precise way to do it, but my method was always to find out the differences between the longest and shortest true-tape measurement for the pipes, and then just use a tape measure to add conductor length to the shorter runs on each end of the termination.

I figure it's good within <12" of actual.


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## Deep Cover

Big John said:


> Maybe there's a more precise way to do it, but my method was always to find out the differences between the longest and shortest true-tape measurement for the pipes, and then just use a tape measure to add the difference to the short ones on each end of the termination.
> 
> I figure it's good within about <12" of actual.


How long of a run are we talking about here? 10' or 100'?

Reason I ask, is when this question was brought up in a code seminar, the inspector stated 10% should be good enough. We thought that was really high.


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## EBFD6

Deep Cover said:


> How long of a run are we talking about here? 10' or 100'?
> 
> Reason I ask, is when this question was brought up in a code seminar, the inspector stated 10% should be good enough. We thought that was really high.


10% seems pretty high, but I have nothing to really back that up. I think 1 or 2% would be more realistic.


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## ponyboy

Deep Cover said:


> How long of a run are we talking about here? 10' or 100'?
> 
> Reason I ask, is when this question was brought up in a code seminar, the inspector stated 10% should be good enough. We thought that was really high.


I don't think inspectors should be throwing numbers out their ass on variance. The code is clear on the requirements of parallel conductors and I try to do everything within reason to make them as close as possible


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## Big John

Deep Cover said:


> How long of a run are we talking about here? 10' or 100'...?


 Any parallel run. Seems like on a short run I was a lot more likely to end up with a significant difference anyway, because maybe one pipe had all the outside bends, or maybe the lug arrangement required one set to be a couple feet longer. 4 feet out of 25 is much more significant than out of 250.


> ...Reason I ask, is when this question was brought up in a code seminar, the inspector stated 10% should be good enough. We thought that was really high.


 I agree with _pony_ I don't think he should be making stuff up off the cuff, and I think realistically, you're often gonna be within 10% even by accident.

But even 10% doesn't seem like a huge deal. 10% length = 10% resistance = 10% current difference. If you're pushing 400A per cable, it means one might be carrying 440A.


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## BBQ

ponyboy said:


> I don't think inspectors should be throwing numbers out their ass on variance. The code is clear on the requirements of parallel conductors and I try to do everything within reason to make them as close as possible


The inspectors have to do that, the NEC leaves them no choice but to do that.

The code says 'the conductors shall be the same length' without giving any tolerance to it. That makes the section imposable to comply with.



> 310.10(H)
> 
> (2) Conductor Characteristics. The paralleled conductors
> in each phase, polarity, neutral, grounded circuit conductor,
> equipment grounding conductor, or equipment bonding
> jumper *shall comply* with all of the following:
> 
> (1) *Be the same length*


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## Deep Cover

BBQ said:


> The inspectors have to do that, the NEC leaves them no choice but to do that.
> 
> The code says 'the conductors shall be the same length' without giving any tolerance to it. That makes the section imposable to comply with.



Shouldn't THAT be what they are saying tho?


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## BBQ

Deep Cover said:


> Shouldn't THAT be what they are saying tho?


How can they require something that is impossible?

You cannot make two conductors 'the same length' at some point you have to say close enough.

Maybe 10% is kind of high, but the code should give some percentage be it 1, 2, 5, 7% etc so that it could be complied with.


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## ponyboy

BBQ said:


> The inspectors have to do that, the NEC leaves them no choice but to do that.
> 
> The code says 'the conductors shall be the same length' without giving any tolerance to it. That makes the section imposable to comply with.


I see your point and its absolutely true. inspectors gotta do what they gotta say but i think its the installers responsibility to try and make the conductors as close as possible every time instead of relying on a made up tolerance. the other point is that this code section is almost impossible to enforce or even check and see if they're the same length so the whole point is moot. its been years since any of my works been inspected but i do try my damndest to try and make my parallel runs identical


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## BBQ

ponyboy said:


> I see your point and its absolutely true. inspectors gotta do what they gotta say but i think its the installers responsibility to try and make the conductors as close as possible every time instead of relying on a made up tolerance. the other point is that this code section is almost impossible to enforce or even check and see if they're the same length so the whole point is moot. its been years since any of my works been inspected but i do try my damndest to try and make my parallel runs identical


I agree on all points. (How often does that happen? :laughing


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## Deep Cover

BBQ said:


> How can they require something that is impossible?
> 
> You cannot make two conductors 'the same length' at some point you have to say close enough.
> 
> Maybe 10% is kind of high, but the code should give some percentage be it 1, 2, 5, 7% etc so that it could be complied with.


I understand what you are saying, but the problem is that the way it is written, every inspector out there will have a different opinion. Without a State amendment, he is just talking out of his ...


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## BBQ

Deep Cover said:


> but the problem is that the way it is written, every inspector out there will have a different opinion.



Exactly, it is written in a way that leaves no choice but to do the best we can. It really needs to be changed a bit.


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## xlink

Has anyone measured the amperage of parallel runs to see what the normal difference in current actually is?

All that work looks pretty nice. I did 7 parallels of 4 conductor 750 cable a few years ago. No way would I post of picture of that. It wouldn't have looked good even if I cut the conductors to different lengths.


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## Peewee0413

Does anyone know what happens when one conduit is right next to rebar?


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## piperunner

Peewee0413 said:


> Does anyone know what happens when one conduit is right next to rebar?


Well nothing happens if your thinking induction effecting the rebar at 60 hz 
and at less than 1000 volts nothing to measure .
Now ask how we know this .


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## BBQ

Peewee0413 said:


> Does anyone know what happens when one conduit is right next to rebar?


Nothing unless it encircles the conductors.


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## Peewee0413

Metal running in between two of the three doesn't conflict? I might need to check into it I guess....


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## BBQ

Peewee0413 said:


> Metal running in between two of the three doesn't conflict? I might need to check into it I guess....


If you had a rebar that ran between isolated phases and was electrically continuous with other rebars that ended up enclosing the single isolated phase I think you could have some heating.

But a single isolated rebar should not be a problem.


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## Peewee0413

Makes sense...


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## piperunner

Peewee0413 said:


> Metal running in between two of the three doesn't conflict? I might need to check into it I guess....


Go back to basic induction theory at 60 hz it would cancel out plus its like a Faraday cage rebar in a deck or wall . 
Ive done high tech sound & audio rooms at universal studios and at Disney were we actually installed a copper cage in the walls rebar does the same .
unless its at a perfect right angle at exact distance and only one phase is induced nothing. Like i said the distance from rebar to the conductor would be so close it would never happen . Read up on induction heating you need high current a coil one loop would heat the rebar and actually melt it . Thats why PVC is used only when you isolate phases .


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## Peewee0413

Im only creating and continuing conversation ....I seen the same pic and conv. Weeks ago on a dif site.


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## piperunner

Peewee0413 said:


> Im only creating and continuing conversation ....I seen the same pic and conv. Weeks ago on a dif site.


Well what was there input on it ? 

Personally if you do this isolation it looks better terminating but effects then length because of stacking conduits underground . 
When you get into distance of length of each conduit of a multi run there never the same length underground there stacked if you measure each the length of one conduit from the next conduit it will be on the average of one foot to 3 foot so this becomes a resistance problem.
Wire heating over time insulation damage . For years what electricians and the NEC should do is install a pull box under gear and eliminate the crossing and the mismatch of length . But thats my thoughts When you separate for looks you add length and now have a increase in current which has more heat generated in this area thats why Florida power will not let secondarys to be installed like this . Resistance of conductors is 
the problem more current will pass in the one thats lower in resistance 
it gets hotter it melts down insulation .


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## BBQ

Peewee0413 said:


> I seen the same pic and conv. Weeks ago on a dif site.



If you are talking about this pic










I can give you a little background on it. 

A friend of mine took this picture while he was doing an IR survey of this gear. He sent me the pic and I have been posting it on the net for a lot of years now.

He had no idea who did the installation or how the conduits are routed out to the pad.


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## don_resqcapt19

If the only difference between the impedance of 8 runs of 500 kcmil is the change caused by length and if the first run is 50' and the other runs increase by 1' each the the 3 shortest runs will be over the 380 amp rating if there is a 3000 amp load.
Note that is it very easy to have other factors, such as the conductor arrangement and terminations that will cause a larger change in the impedance of the paths than the change caused by increasing the length.


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## piperunner

don_resqcapt19 said:


> If the only difference between the impedance of 8 runs of 500 kcmil is the change caused by length and if the first run is 50' and the other runs increase by 1' each the the 3 shortest runs will be over the 380 amp rating if there is a 3000 amp load.
> Note that is it very easy to have other factors, such as the conductor arrangement and terminations that will cause a larger change in the impedance of the paths than the change caused by increasing the length.


Well a typical 4000amp service lets say it has 13 runs of 750 mcm alu this would include voltage drop per engineer design . When your run these underground 4 runs will be 3 ft longer 4 runs will be 2 ft longer and 4 runs will be 1 ft longer and the last one of 13 will be the shortest run you can not install these underground any other way they will be off . To adjust for length make all the runs the longest length and the shortest conduit runs will have the extra slack which looks like crap inside gear .
What iam saying is no one in the field ever does this ever its not done they make up the gear and its done . Today with Infa red testing its a issue you can see the hotter conductors . Also the engineer always sizes the conductors larger on most projects . Which i see as a buffer to correct the minor problem .


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## Deep Cover

That is exactly the way we do it. Cut the conductors at "equal" lengths, and find room to bend the conductors around so they fit in the gear.


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## xlink

Deep Cover said:


> That is exactly the way we do it. Cut the conductors at "equal" lengths, and find room to bend the conductors around so they fit in the gear.


If you were to run cables, there is no other way. Usually you have to cut them anyway, so you just cut the same amount off each same phase.

It's pretty rare that a 4000 amp service actually runs at 4000 amps and if it does it probably wouldn't be for very long. Heating takes time so the wires that are overloaded don't have much time to heat.

I've measured the current on parallel runs and sometimes it's pretty even, but I've seen them off about 10% too. Maybe the connections aren't all the same. It's hard to tell with a fluctuating load and only one meter.

I've also seen short runs that were very different. Not everyone cares, it seems. The stuff keeps running.

I've seen #2 parallel runs (min here is 1/0). No problems.

I've seen 500 parallel with 1500. As long as the 500 can handle its share of the load - no problems.

The discussion starts to seem academic when nothing bad ever happens. So, just do the best you can. Given the choice between bending a high voltage cable too tight and cutting it a few inches short, I would cut the wire (again).


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## Shockdoc

BBQ said:


> It looks great and it is fun work.
> 
> Next time you might want to consider doing it like this, it saves a lot of chris crossing


 Who hacked that lower cut around the conduits?


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## piperunner

Well heres some terminations we try to get them the same length but its not easy it depends if you have space also not just service mains but other feeders . Some times you cant they do not have room inside to leave the extra length req by the NEC i think they should make gear bigger .


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