multiconductor cable derating

[mikehughes8]

More Than Three Current-Carrying Conductors in a Raceway or Cable.

Where the number of current-carrying conductors in a raceway or cable exceeds three, or where single conductors or multiconductor cables are installed without maintaining spacing for a continuous length longer than 600 mm (24 in.) and are not installed in raceways, the allowable ampacity of each conductor shall be reduced as shown in Table 310.15(B)(2)(a). Each current-carrying conductor of a paralleled set of conductors shall be counted as a current-carrying conductor.

Am I correct to reason from this article with multiconductor direct buried cable (as long as I maintain proper condcutor spacing) I do not need to derate for parallel runs?
At the point of entrance into my panel the conductors will lose that spacing. As long as it is not for a lenght of more than 2' I am ok. Is that correct???

 

[ibew441dc]

Parallel Runs of the same circuit or seperate ones?

Parallel Runs of the same circuit or seperate ones?

More Than Three Current-Carrying Conductors in a Raceway or Cable.

Where the number of current-carrying conductors in a raceway or cable exceeds three, or where single conductors or multiconductor cables are installed without maintaining spacing for a continuous length longer than 600 mm (24 in.) and are not installed in raceways, the allowable ampacity of each conductor shall be reduced as shown in Table 310.15(B)(2)(a). Each current-carrying conductor of a paralleled set of conductors shall be counted as a current-carrying conductor.

Am I correct to reason from this article with multiconductor direct buried cable (as long as I maintain proper condcutor spacing) I do not need to derate for parallel runs?
At the point of entrance into my panel the conductors will lose that spacing. As long as it is not for a lenght of more than 2' I am ok. Is that correct???

With out digging to deep are you using the term parallel runs to describe more than one single or multiconductor cable being used as the same circuit.Or multiple single or multiconductor cables, as seperate circuits, paralleling each other in the same trench? I'm not questioning your understanding...just want to make sure I'm on the same page:smile:

 

[ibew441dc]

Excellent Topic!

Excellent Topic!

300.5(I) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors shall be installed in the same raceway or cable or shall be installed in close proximity in the same trench.

310.4(A) General. Aluminum, copper-clad aluminum, or copper conductors of size 1/0 AWG and larger, comprising each phase, polarity, neutral, or grounded circuit conductor shall be permitted to be connected in parallel (electrically joined at both ends)

The point I was trying to make was this...if you are paralleling conductors in accordance with the rules listed above conductors of the same circuit, paralleled or not, must be located in close proximity in the same trench.This being said 310.15(B)(2)(A) is applicable and adjustment is required.

If they are separate runs of..... lets say (10) 30 amp branch circuits of 10-3 UF cable from point A to B......separate each circuit to avoid the bundling adjustment.

 

[mikehughes8]

I have it. I was just reading to much into the article I referenced earlier. The seperation through me off. In MV applications (in a trench) we maintain intentional seperation and my mind was stuck on that.

 

[Pierre C Belarge]

More Than Three Current-Carrying Conductors in a Raceway or Cable.

Where the number of current-carrying conductors in a raceway or cable exceeds three, or where single conductors or multiconductor cables are installed without maintaining spacing for a continuous length longer than 600 mm (24 in.) and are not installed in raceways, the allowable ampacity of each conductor shall be reduced as shown in Table 310.15(B)(2)(a). Each current-carrying conductor of a paralleled set of conductors shall be counted as a current-carrying conductor.

Am I correct to reason from this article with multiconductor direct buried cable (as long as I maintain proper condcutor spacing) I do not need to derate for parallel runs?
At the point of entrance into my panel the conductors will lose that spacing. As long as it is not for a lenght of more than 2' I am ok. Is that correct???

The phrase, 'maintaining spacing' confuses some people. There is no definition of measurement given, so we just try to use some common sense.