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500MCM for the first time

16K views 59 replies 25 participants last post by  Tsmil 
#1 ·
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
 
#5 · (Edited)
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 .
 

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#22 ·
ghostwriter said:
See 310.15(B)(2): Each current carrying conductor of a paralleled set of conductors shall be counted as a current-carrying conductor. As the engineer is increasing the neutral, I am under the assumption that a major portion of the load consists of nonlinear or harmonic loads. I would consider this as 5 current carrying conductors requiring derating.
I didn't think if it as a paralleled "set". It's not a full parallel as it's only a "Pair" of neutrals. It's Squeaking on the words used, but I believe the intent is derating isn't required.
I would call it 4 CCC
 
#24 ·
Wirenuting said:
I didn't think if it as a paralleled "set". It's not a full parallel as it's only a "Pair" of neutrals. It's Squeaking on the words used, but I believe the intent is derating isn't required. I would call it 4 CCC
. I agree . The 200% neutral is not the same as a parallel set of conductors . Even if you counted it and derated , I'm sure the 500's are oversized anyway . They are if an engineer sized them anyway , lol ?
 
#26 ·
A Good Electrician said:
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
. A full sized ground ? I've never heard of that , even on a system with isolation transformers and 200% neutrals ? This came from an EE ?
 
#27 ·
wow. you are going to pull the ship out of that. we had an engineer have us pull 8 4/0s and it sucked. pulled 1/2 inch steel drop in out of the floor. get some jiss bags. thats what we call them at least. narrow bags of poly j that you tie on in front of the head. slit the bags and around the 90s it will squeeze out. and soap the crap out of each conductor individually. it helps.
 
#31 ·
I'd at least try pushing them in one at a time.

A few months ago I had a somewhat similar situation; a 3" EMT going out the top of a switchboard, a 90 about 3' up, another 90 going down into a MCC. Total length was about 20'.

I was able to push 6 - 350s and a ground in one at a time. I pushed the ground in first since it is less rigid than the 350s, and the last one sort of fought me a bit, but it wasn't hard. And it took only one guy, not 3 or 4, plus no time involved in making up the head.

The wire was basic CU THHN. I don't think it was Simpull, because I could grip it easily.
 
#34 ·
Oh, and if you have a really long pull, it may be worth your while to rent a feeder. They can be indispensable.

Do not stand directly inline with the rope coming off the tugger. If it snaps, you could be dead. Stand to the side. If someone is feeding the wires, make sure they don't get their hand pinched in the wires as it goes in. It will surge and could really hurt you.
 
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