Parallel Conductors in Separate Conduit.

[horrorsix]

We're installing a 600A/ 480V 3? service with a neutral 485' from the disconnect. We're running 2 sets of 4- 500MC AL wire. 8 total 500MCM wires. I've never installed a circuit this big with so far of a run. Is it common practice to run this in 2 conduit runs? If so how would it be split up? 2 phases in 1 conduit and the 3rd phase and neutral in the other? Or should all 8 wires be pulled in one conduit? Not sure what is commonly done in this situation.

Thanks

 

[masterinbama]

A-B-C-N in each conduit.

 

[horrorsix]

Thank you.

 

[augie47]

300.3(B)
(B) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors and bonding conductors shall be contained within the same raceway, auxiliary gutter, cable tray, cablebus assembly, trench, cable, or cord, unless otherwise permitted

 

[don_resqcapt19]

300.3(B)
(B) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors and bonding conductors shall be contained within the same raceway, auxiliary gutter, cable tray, cablebus assembly, trench, cable, or cord, unless otherwise permitted

If you stop reading the section there, then you would think that all of the sets of paralleled conductors would have to be in a single raceway. You have to continue on to 300.3(B)(1) to see that the main rule applies to each set of parallel conductors separately.

 

[infinity]

Any concern with voltage drop?

 

[augie47]

If you stop reading the section there, then you would think that all of the sets of paralleled conductors would have to be in a single raceway. You have to continue on to 300.3(B)(1) to see that the main rule applies to each set of parallel conductors separately.

opppps

 

[Smart $]

Any concern with voltage drop?

At that distance, that's what I'm wondering...

 

[m sleem]

We're installing a 600A/ 480V 3? service with a neutral 485' from the disconnect. We're running 2 sets of 4- 500MC AL wire. 8 total 500MCM wires. I've never installed a circuit this big with so far of a run. Is it common practice to run this in 2 conduit runs? If so how would it be split up? 2 phases in 1 conduit and the 3rd phase and neutral in the other? Or should all 8 wires be pulled in one conduit? Not sure what is commonly done in this situation.

Thanks

I don't really know the availability on site, but you can use 6"conduit to include all of your conductors + grounding.

 

[Smart $]

I don't really know the availability on site, but you can use 6"conduit to include all of your conductors + grounding.

Then he has to derate the conductor's ampacity...

 

[charlie b]

Then he has to derate the conductor's ampacity...

It would still be acceptable. Even if you count the neutral as a CCC, due to harmonics, the derate factor of 70% times the ampacity of two 500's (using the 90C value of 430) gives you 602 amps.

 

[Smart $]

It would still be acceptable. Even if you count the neutral as a CCC, due to harmonics, the derate factor of 70% times the ampacity of two 500's (using the 90C value of 430) gives you 602 amps.

That's for copper conductors. OP stated aluminum.

 

[electrofelon]

We're installing a 600A/ 480V 3? service with a neutral 485' from the disconnect. We're running 2 sets of 4- 500MC AL wire. 8 total 500MCM wires. I've never installed a circuit this big with so far of a run. Is it common practice to run this in 2 conduit runs? If so how would it be split up? 2 phases in 1 conduit and the 3rd phase and neutral in the other? Or should all 8 wires be pulled in one conduit? Not sure what is commonly done in this situation.

Thanks

I would consider running three sets of 250 al. Each pipe has A B C and neutral. Large wire gets real inefficient. Comparing 250 to 500, 500 has twice the area but only 50 % more ampacity. What kind of pipe do you plan to run? Don't forget that if you pull an egc, with parallel conductors you need a full size egc in EACH conduit, so if it were me and it was emt, I would use the raceway as the EGC ( don't forget your more stringent bonding rules for over 250v).