Here's my question:
At 75C, 350MCM AL is 250A. Let's say I have one set of 350MCM AL as existing SERVICE-ENTRANCE CONDUCTORS to an existing building and I want to connect new copper to it from a new utility transformer. The existing AL terminates at a panel with a 200A main circuit breaker. Let's assume I cannot come out of the transformer with aluminum, only copper. If I splice the existing aluminum:
#1: with 350MCM Cu using a listed connector for the application - is this now a TAP since 350MCM Cu is rated for 310A and AL is rated for 250A at 75C?
#2: does #1 matter since 230.46 permits tapping service-entrance conductors?
#3: to avoid being considered a TAP, and to maintain status as a SPLICE, do I run wire with ampacity close to or equivalent to AL, so in my case, 250MCM Cu (255A) or 4/0 Cu (230) - this seems silly as I'm typing it.
Here's why I'm asking:
I've seen many discussions about "splicing" copper to aluminum, and reviewed the previous post here: http://forums.mikeholt.com/showthread.php?t=132036
I don't have OCPD upstream of my splce/tap because it's a transformer secondary and I'm not required to by the utility company - I checked with them. I only have the MCB in my building panel that is limiting the amperage to 200A, thus protecting the existing 350MCM AL and my new copper (sized to carry 200A or more, of course).
I have 350' of fairly recently installed 350MCM AL in direct buried PVC feeding a building on a large open campus. Client understandably wants to reuse as much as possible. I've run the calcs and no issues with load and voltage drop - this is a small building.
I planned to install copper service-entrance conductors from the utility transformer complete to the other buildings, so I'd like to stay with copper out of the transformer/manhole and simply splice the existing 350MCM AL to this one building in a handhole.
Thanks for reading.
At 75C, 350MCM AL is 250A. Let's say I have one set of 350MCM AL as existing SERVICE-ENTRANCE CONDUCTORS to an existing building and I want to connect new copper to it from a new utility transformer. The existing AL terminates at a panel with a 200A main circuit breaker. Let's assume I cannot come out of the transformer with aluminum, only copper. If I splice the existing aluminum:
#1: with 350MCM Cu using a listed connector for the application - is this now a TAP since 350MCM Cu is rated for 310A and AL is rated for 250A at 75C?
#2: does #1 matter since 230.46 permits tapping service-entrance conductors?
#3: to avoid being considered a TAP, and to maintain status as a SPLICE, do I run wire with ampacity close to or equivalent to AL, so in my case, 250MCM Cu (255A) or 4/0 Cu (230) - this seems silly as I'm typing it.
Here's why I'm asking:
I've seen many discussions about "splicing" copper to aluminum, and reviewed the previous post here: http://forums.mikeholt.com/showthread.php?t=132036
I don't have OCPD upstream of my splce/tap because it's a transformer secondary and I'm not required to by the utility company - I checked with them. I only have the MCB in my building panel that is limiting the amperage to 200A, thus protecting the existing 350MCM AL and my new copper (sized to carry 200A or more, of course).
I have 350' of fairly recently installed 350MCM AL in direct buried PVC feeding a building on a large open campus. Client understandably wants to reuse as much as possible. I've run the calcs and no issues with load and voltage drop - this is a small building.
I planned to install copper service-entrance conductors from the utility transformer complete to the other buildings, so I'd like to stay with copper out of the transformer/manhole and simply splice the existing 350MCM AL to this one building in a handhole.
Thanks for reading.