I have an application that requires the use of 535.3 MCM Locomotive cable to be installed in PVC under ground and (3) per conduit. The manufacturer only gives the rating of DLO as 725 amps per conductor based on single cond. in free air. What is the correct way to derate for (3) in conduit? I have looked at the Tables 310-17 (free air) and 310-16(not more than 3 Cond) and have found no direct multiplier to use except a .62 multiplier seems to come close on some of them.
Diesel Loco Cable
- Thread starter wattup
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Ragin Cajun
Senior Member
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- Upstate S.C.
I can see using this cable for flexibility issues, but why underground? Seems a waste of $ and a PITA in coming up with the ampacity rating.
Of course, I don't know the whole story, but what's that matter in an answer. ;-)
Of course, I don't know the whole story, but what's that matter in an answer. ;-)
sandsnow
Senior Member
- Location
- Southern California
I believe this locomotive cable is listed as RHW, but I could be wrong.
You do not derate for 3 conductors. Use table 310.16 for the ampacity under the 500kcmil row.
I would say use 600kcmil for figuring conduit fill. Or get actual area spec from manufacturer.
BTW, you need terminations specifically designed for that fine stranded conductor.
If you are dealing with an AHJ, consider the following.
535.3 kcmil is not a Code recognized size. Special Permission could be granted for use at an ampacity higher than 500 kcmil. It is reasonable for this to be done as long as the cable is listed. Possibly you could use engineering supervision to find the ampacity.
You do not derate for 3 conductors. Use table 310.16 for the ampacity under the 500kcmil row.
I would say use 600kcmil for figuring conduit fill. Or get actual area spec from manufacturer.
BTW, you need terminations specifically designed for that fine stranded conductor.
If you are dealing with an AHJ, consider the following.
535.3 kcmil is not a Code recognized size. Special Permission could be granted for use at an ampacity higher than 500 kcmil. It is reasonable for this to be done as long as the cable is listed. Possibly you could use engineering supervision to find the ampacity.
I work a lot with this cable. First make sure it is dual rated DLO and RHH/RHW. As long as it has RHH/RHW you can use it.
As stated there is no derating for just 3-conductors. Use 500-MCM row in the tables and you will be fine.
Termination is the most critical installation task. The lugs have long barrels and require special hydryalic compression tools with matching dies for the size and lug type. All I specify require 4 to 8 crimps each. Very labor intensive.
As stated there is no derating for just 3-conductors. Use 500-MCM row in the tables and you will be fine.
Termination is the most critical installation task. The lugs have long barrels and require special hydryalic compression tools with matching dies for the size and lug type. All I specify require 4 to 8 crimps each. Very labor intensive.
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