hardworkingstiff
Senior Member
- Location
- Wilmington, NC
In previous threads I have asked about using type W cable at marinas and we've discussed how even though Table 400.5(B) allows for a higher ampacity than 310.16, 110.14(C) limits you to 310.16 due to temperature limitations (unless equipment is listed otherwise).
At the power center, we often will loop feed a couple/three power centers on one feeder. One particular power center we use has a copper buss bar and studs for our terminations. We use a UL listed lug on the type W cable (and a listed crimp). These lugs are bolted to the buss bar back to back.
Let's use the example of a 1/0 W cable on a 120/240-volt feeder. Using 400.5(B) at 75C we have an ampacity rating of 207-amps (I think). Let's say we are loop feeding a power center that has (2) 50-amp receptacles and dead-ending at a 2nd power center that has (2) 50-amp receptacles. The cable has an adequate ampacity but 110.14(C) does not allow it (at least that is the consensus from previous threads) because it limits the terminations to 310.16 ampacities.
Here is an argument I'm thinking about making and I'm asking for feedback.
The 1st power center has the lugs bolted back to back. This type of connection is an approved connection (i.e. motors). Since all the current that goes to the 2nd power center will pass from the feed in lug to the feed out lug (yes, while they are both bolted to the buss bar), the buss bar will actually not see/feel the current that is just passing through. Therefore, the buss bar will only ever see/feel the current that is being used by that particular power center and not anything that is being used by the 2nd power center. Can we then say that the "termination" at the 1st power center is only 100-amps and not 200-amps?
At the power center, we often will loop feed a couple/three power centers on one feeder. One particular power center we use has a copper buss bar and studs for our terminations. We use a UL listed lug on the type W cable (and a listed crimp). These lugs are bolted to the buss bar back to back.
Let's use the example of a 1/0 W cable on a 120/240-volt feeder. Using 400.5(B) at 75C we have an ampacity rating of 207-amps (I think). Let's say we are loop feeding a power center that has (2) 50-amp receptacles and dead-ending at a 2nd power center that has (2) 50-amp receptacles. The cable has an adequate ampacity but 110.14(C) does not allow it (at least that is the consensus from previous threads) because it limits the terminations to 310.16 ampacities.
Here is an argument I'm thinking about making and I'm asking for feedback.
The 1st power center has the lugs bolted back to back. This type of connection is an approved connection (i.e. motors). Since all the current that goes to the 2nd power center will pass from the feed in lug to the feed out lug (yes, while they are both bolted to the buss bar), the buss bar will actually not see/feel the current that is just passing through. Therefore, the buss bar will only ever see/feel the current that is being used by that particular power center and not anything that is being used by the 2nd power center. Can we then say that the "termination" at the 1st power center is only 100-amps and not 200-amps?