Hi,
I have a project where I am splicing at a manhole and extending conductors to a new substation (medium voltage, 4160V). My question is in regards to the underground conductor ampacity ratings shown on Table 310.60(C)(77). I am running only two conduits and circuits together from the manhole to my new sub. So I am going to use the ampacities under the "three circuit" portion of the table. But this got me thinking...how do you apply this for a conductor that goes through multiple manholes and different duct configurations? The conductors I am splicing have come from a main substation upstream but has span through other manholes, splices and different duct bank configurations. So where exactly do I apply the ampacities? If I took the "worst case" from the upstream substation to my new substation, it would be near the upstream substation where there are up to 8 different conduits in one area. But this would cause my ampacity of 500 KCMIL conductors to be severely decreased. These conduits split up as the travel to downstream substations so I'm unsure what to do.
I have a project where I am splicing at a manhole and extending conductors to a new substation (medium voltage, 4160V). My question is in regards to the underground conductor ampacity ratings shown on Table 310.60(C)(77). I am running only two conduits and circuits together from the manhole to my new sub. So I am going to use the ampacities under the "three circuit" portion of the table. But this got me thinking...how do you apply this for a conductor that goes through multiple manholes and different duct configurations? The conductors I am splicing have come from a main substation upstream but has span through other manholes, splices and different duct bank configurations. So where exactly do I apply the ampacities? If I took the "worst case" from the upstream substation to my new substation, it would be near the upstream substation where there are up to 8 different conduits in one area. But this would cause my ampacity of 500 KCMIL conductors to be severely decreased. These conduits split up as the travel to downstream substations so I'm unsure what to do.
