[A Good Electrician]

Hey Guys. So, Im here at Raytheon Again in Los Angeles. They are upgrading a lab and pulling an 800amp feed from a Substation to feed the panels being added. So, my question is about the 800amp feeder/raceway. The in house engineers have called for a 200%neutral and sized the ground at 500MCM as well for a total of (6) 500MCM's in a 4" Rigid. Now, according to the NEC that is fine. You can put (7) 500MCM's in a 4"rigid. But it leaves little room and we have one standard (not a big sweep) 90 degree bend. Can I get some thoughts on the difficulty here with such a tight fit. Or, it is what it is and we need to just soap that baby up? Any help would be much appreciated. Tahnk guys.

Ben

 

[Awg-Dawg]

Wow, Ive never seen that many in one raceway.

How long of a run?

 

[MWayne]

How long of a pull? The guys here who are experts at this will need to know.

 

[fp.unit]

First big conductors I saw we're 4x 750s in a 4" pipe and I thought that was packed. We ran multiple sets of 4 in multiple 4" pipes with a 5 guys and a tugger

 

[piperunner]

Hey Guys. So, Im here at Raytheon Again in Los Angeles. They are upgrading a lab and pulling an 800amp feed from a Substation to feed the panels being added. So, my question is about the 800amp feeder/raceway. The in house engineers have called for a 200%neutral and sized the ground at 500MCM as well for a total of (6) 500MCM's in a 4" Rigid. Now, according to the NEC that is fine. You can put (7) 500MCM's in a 4"rigid. But it leaves little room and we have one standard (not a big sweep) 90 degree bend. Can I get some thoughts on the difficulty here with such a tight fit. Or, it is what it is and we need to just soap that baby up? Any help would be much appreciated. Tahnk guys.

Ben

Well on our project right now I have 200% neutrals all over the building this is our engineers design a 800amp feeder gets 500 MCM phases 500 MCM for neutral x 2 and a 250 mcm ground now if we have 200% neutral with a isolated ground then its two grds We have no trouble pulling this in a 4 inch conduit we bend our EMT but why 6x500 MCM that's over kill .Is it a long one voltage drop ?
We been pulling 6 or 7 wires in for 4 months lots of fun why the big ground must be long how long.
And we don't use soap simpull wire



TYPICAL RUNS 800 amp 4 runs 500mcm ph 500mcm x 2 neutral 200 % a 250 mcm ground 4 inch conduit
1200amp 4 runs 500mcm ph 500 mcm neutrals 250 mcm ground 4 inch conduit
600amp 2 runs 500 mcm 500 mcm neutrals 2/0 ground 4 inch conduit

2000 amp 6 runs 4 inch 600 mcm phases 600 mcm neutral x2 500 mcm ground x2 if isolated ground this is all alu wire simpull 3 men feed one man tugs we use a Greenlee UT10 tugger wire feeder Greenlee even with out the wire feeder we use 3 men feedering we get our wire on one spool by south wire all phases neutral and ground one spool.
The tugger maxed out at 2000 lbs to 4000lbs at times but slides right in and we are pulling most of the time via two pull boxes straight with 6x90 degree bends total bends . Simpull wire that is the best wire today you can not damage it with no soap used . That's a 500 kva 6 runs in the photo we have 12 of these on site with 200 % neutrals and isolated grounds 7 wires .

 

[micromind]

How long is the run?

With one 90, it would be fairly easy if it's short.

If it's really short, like less than 20', I'd try pushing them in one by one. Yes. it'll go; I've done it a few times with big wire even if the pipe is stuffed.

 

[cal1947]

tofer1947

Wow, Ive never seen that many in one raceway.

How long of a run?

i would not try that on anything over ten foot with a 90 , plus you have to derat the condutors

 

[Awg-Dawg]

plus you have to derat the condutors

Why is that?

 

[HawkShock]

Why is that?

Make sure there are no rats in the conductors, that is why. Rats aren't very conductive.

 

[Awg-Dawg]

Make sure there are no rats in the conductors, that is why.

I was reading this and was thinking WTF?

I went back and read the post.:laughing:

 

[bkmichael65]

In addition to rats in the conduit, if they stuff 6 current carrying conductors in one pipe, they're going to have to derate 80%

 

[Awg-Dawg]

if they stuff 6 current carrying conductors in one pipe, they're going to have to derate 80%

Am I reading the OP wrong?

 

[bkmichael65]

Am I reading the OP wrong?

Either that or I'm reading it wrong

 

[Awg-Dawg]

Either that or I'm reading it wrong

A,B,C, N,N,G


6 conductors each pipe.

Because of the increased Nuetral do you consider it current carrying?

 

[A Good Electrician]

A,B,C, N,N,G


6 conductors each pipe.

Because of the increased Nuetral do you consider it current carrying?

I will admit I don't know what code to quote in my answer, this is just my educated opinion. Yes. It's purpose is to absorb additional current flow as a result of linear loads. Again, I would say yes. And, I'm not sure if i mentioned in original post but the raceway is (3) RUNS 4" rigid conduit. (6) 500MCM per conduit. A,B,C,N,N,G as you mentioned.
However, my concern is the pulling of these (6) conductors in a conduit that Technically can hold (7), but seems very tight. Has anyone pulled in this or a similar situation? There will be (1) 90 degree bend in this run.

 

[A Good Electrician]

Only 26'. One 90 degree bend coming from the top of a substation and then straight into the back of a large pull box directly above the distribution panel it will feed.

 

[A Good Electrician]

I agree with you about the ground as well. I have a confirming RFI already submitted to change ground to 250MCM.

 

[bkmichael65]

A,B,C, N,N,G


6 conductors each pipe.

Because of the increased Nuetral do you consider it current carrying?

No, I was reading the OP wrong. That's going to be a tight fit. He may want to stagger the conductors so they don't come through that 90 all at once

 

[Ultrafault]

I agree with you about the ground as well. I have a confirming RFI already submitted to change ground to 250MCM.

They probably did that on purpose. Some idiot ees think the ground is magic and more of it makes electric more betterer.

 

[piperunner]

I agree with you about the ground as well. I have a confirming RFI already submitted to change ground to 250MCM.

Well I see there already on you about derating you don't have to derate .
the neutral is one counted as one the current splits .
The code says number of current wires in a conduit it may but the code issue or comments is wrong in this condition .Even with the four if you derate your wire is way beyond the ampacity of what your 800 amp breaker is so your ok .

Just another code rule that needs to be changed or rewritten to include all types of work . The only rule we follow is the 25 foot tap rule on theses.LOL