- Location
- New Jersey
- Occupation
- Journeyman Electrician
That lug accepts 3 conductors?
when to use 90 degrees ampacity conductor?
- Thread starter skyline77
- Start date
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That lug accepts 3 conductors?
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Yes, but you need to splice at both ends. Make sure the cost of the splices and j box, labor etc is worth the cost difference.
Carultch
Senior Member
- Location
- Massachusetts
As long as you are landing in an enclosure that is nothing but busbar, or you are splicing in an enclosure that starts empty, you can take credit for 90C terminal ratings, and use this as either a value-engineering solution or a method to recover from a mistake. In otherwords, once you are in equipment that is 75C rated, even field-installed connectors require assuming a 75C rating. Keep in mind that you likely still have ambient temperature derate factors that may apply, and now you no longer have de-facto margin on top of the terminal ampacity to account for them.
I'm not familiar with using crimp lugs landing on other crimp lugs, so you'll need to check with the manufacturer to know if you do that. I'm usually familiar with crimp lugs being fastened to busbars, or fastened to equipment terminations. To do this solution, I'd recommend insulated tap connectors, such as Polaris blocks.
It won't work the cables we have are 1250 Kcmil.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
you can derate portions of the run where necessary using 90 ampacity values as your starting point, if you are landing on a 75C terminal, you still need at least 75C table sized conductor as minimum conductor size at that terminal.
You might find a crimp on lug rated 90C. You still would need to use 75C conductor if you land that lug on equipment with 75C rating. Lowest temp rating in the connection is the weakest point and you must base everything in that connection on that weakest point.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Good question, seems maybe his intentions weren't what I first thought. Looked up this lug it accepts a single 1250kcmil conductor, has two holes for mounting studs that are 1/2 diameter holes. The thing does have a 90C rating, but like I said in previous post, if you land it on something rated 75C you still stuck with using 75 C conductor ampacity.
Devin Hanes
Member
- Location
- United States
They make these in 1250, and two holes for your two 400s. Calculate voltage drop.The location that requires the 75 C is the circuit breaker terminals and I can use 75 C conductor ampacity when terminating the conductors @ the CB, however, I can connect the 75 C conductors to 90 C conductors for the long run.
We have 13.8 Kv/ 400 V, three-phase 2000 KVA transformer and the distance from the transformer low voltage terminals to the main CB are about 15 meters.
The current per phase is about 2887 Amps and to size the cables the ampacity is 3608 Amps.
So, using 1250 Kcmil we require 6 runs per phase plus neutral. Running 24 cables of 1250 is adequate and one Equipment Grounding Conductor of 500 Kcmil per Table 250.122.
But, we have a large motor that is around 130 meters away from the transformer and its FLA is 322 Amps, 3phase 400 V. So, for an ampacity of 403, we can use 500 Kcmil with 90 C rating, however, if we choose a 600 Kcmil 75 C rating it costs more.
romex jockey
Senior Member
- Location
- Vermont
- Occupation
- electrician
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Bold information is your main topic? You keep mentioning these 1250 conductors but appears they are feeder or service and your main topic is about the branch circuit for a 322 amp motor.
You can run a short length of 600 splice it with 90C splicing method and then run 500 @ 90C. Keep in mind you still need to adjust those for ambient temp or number of conductors in raceway if conditions justify, and there is no higher starting point in this case.
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