Limitations of running two or more sets of conductors

[SivajiSidhu]

Hi Sir/Madam,

I know, we can combine 2 or more multiple sets of conductors in a single conduit with in the limits of 40% filling.

But can you please confirm is there any limitations with respect to the cable size while combining into one conduit? If yes what is the maximum size of cables that I can combine?

In other words Can I combine 2 sets of 4/0 Awg 600V Al cables in one 4" conduit?

Please provide your responses.

Thanks in advance
Naga Sivaji G

 

[infinity]

If by mulitple sets you mean more than 3 current carrying conductors then you'll need to comply with. 310.15(B)(3).

 

[petersonra]

Hi Sir/Madam,

I know, we can combine 2 or more multiple sets of conductors in a single conduit with in the limits of 40% filling.

But can you please confirm is there any limitations with respect to the cable size while combining into one conduit? If yes what is the maximum size of cables that I can combine?

In other words Can I combine 2 sets of 4/0 Awg 600V Al cables in one 4" conduit?

Please provide your responses.

Thanks in advance
Naga Sivaji G

In general, you can put as many conductors in a conduit as you want with the constraints being the code allowed fill, and whatever derating might be required for having more than 3 current carrying conductors.

Cable size does not directly come into play.

 

[SivajiSidhu]

In general, you can put as many conductors in a conduit as you want with the constraints being the code allowed fill, and whatever derating might be required for having more than 3 current carrying conductors.

Cable size does not directly come into play.

Is that not a problem of cable pulling, If we run two large size cables in one conduit? And is there any other issues ?

 

[petersonra]

Is that not a problem of cable pulling, If we run two large size cables in one conduit? And is there any other issues ?

You will need to calculate the pulling force required to make sure it is not excessive for the conductors being pulled, but you would need to do that anyway. But nothing in the code prevents you from running multiple large size conductors in the same conduit.

We get a lot of open ended questions like this. It is hard to answer what your real question is without you being more specific on what it is you want to do, or what your concern is.

 

[SivajiSidhu]

You will need to calculate the pulling force required to make sure it is not excessive for the conductors being pulled, but you would need to do that anyway. But nothing in the code prevents you from running multiple large size conductors in the same conduit.

We get a lot of open ended questions like this. It is hard to answer what your real question is without you being more specific on what it is you want to do, or what your concern is.

Okay Thank you for the response.
I would like to know is there any code for preventing us to combine large size cables. Got it now

 

[wwhitney]

In other words Can I combine 2 sets of 4/0 Awg 600V Al cables in one 4" conduit?

Per NEC, one set of <= 3 CCCs of 4/0 AWG Al conductors would have a 75C (termination limit) ampacity of 180A. If you put 2 sets in the same conduit, the ampacity would drop to 0.8 (adjustment factor for 4-6 CCCs) * 205A (90C ampacity assuming 90C insulation) = 164A each set. So the question is whether 164A per set is sufficient for your application, or if you need the full 180A per set.

Cheers, Wayne

 

[SivajiSidhu]

Per NEC, one set of <= 3 CCCs of 4/0 AWG Al conductors would have a 75C (termination limit) ampacity of 180A. If you put 2 sets in the same conduit, the ampacity would drop to 0.8 (adjustment factor for 4-6 CCCs) * 205A (90C ampacity assuming 90C insulation) = 164A each set. So the question is whether 164A per set is sufficient for your application, or if you need the full 180A per set.

Cheers,