wire ampacity
- Thread starter lesh
- Start date
- Status
- Location
- Massachusetts
Need a lot more details to provide any kind of accurate answer.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Define an open raceway? What type of insulation? Conductor material? As Bob said more info is required.
mayanees
Senior Member
- Location
- Westminster, MD
- Occupation
- Electrical Engineer and Master Electrician
Off the cuff with ALOT of assumptions made to fill in the gaps (see specific questions in other posts) the amperage would be 3040 amps. This assume copper THHN condutors, 75 degree terminations and a "typical" parralell installation. I do not know what an "open" raceway is so this may or may not factor into the answer.
- Location
- Massachusetts
A few more questions.
- What is the ambient temp?
- Is the run out in the sun?
- Are the conductors subject to derating?
Minuteman
Senior Member
- Location
- The Sooner Nation
Is an open raceway the same thing as a cable tray?
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
These two tidbits have no impact on ampacity. Why are you asking this question? Is is some kind of homework assignment, or is this related to an actual installation?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I hope it's for homework.....
No its not home work, I want to make sure that the existing installation wire ampacity is correct for the breaker, a maintenace super. said the installation , years ago was not to its proper ampacity, According to nec 2008 art. 310.16, the ampacity could be 380amps. But this installtion has more than 3 current carrying conductors.
dana1028
Senior Member
- Location
- San Francisco Bay area
cable tray
cable tray
IF, your installation complies with 392.9(C)(1)...then no derating is required and each cable value is 380A.
cable tray
IF, your installation complies with 392.9(C)(1)...then no derating is required and each cable value is 380A.
- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
Within the context of the NEC, cable trays are not raceways.
For cable 0-2000V, the ampacity is calculated per Section 392.11. In general, 310.15(B)(2)(a) will only apply to multi-conductor cables with four or more current carrying conductors.
Beyond the factors you have already clarified, the conductor layout within the tray, the tray?s ventilation method (if any) and whether the cables are single or multi conductor are also relevant. As always, ambient temperature is also relevant.
Cable layout is often a critical issue and easily overlooked. Section 392.11 assumes the conductors are installed per Sections 392.9 or 392.10, whichever is appropriate.
For cable 0-2000V, the ampacity is calculated per Section 392.11. In general, 310.15(B)(2)(a) will only apply to multi-conductor cables with four or more current carrying conductors.
Beyond the factors you have already clarified, the conductor layout within the tray, the tray?s ventilation method (if any) and whether the cables are single or multi conductor are also relevant. As always, ambient temperature is also relevant.
Cable layout is often a critical issue and easily overlooked. Section 392.11 assumes the conductors are installed per Sections 392.9 or 392.10, whichever is appropriate.
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