We are in the process of implementing direct buried for solar panels DC runs. If I want to put DC cables in one single trench, does this count as having "x" cables in a single raceway? If so, what spacing can I implement so it does not count as a single raceway? Is there a minimum spacing I should have for the DC cables? Does the NEC say anything about direct buried DC cables or is there a white paper someone know I can reference for this type of installment? Thank you!
NEC on Direct Buried Underground DC Cables
- Thread starter bea.m
- Start date
- Location
- Illinois
- Occupation
- retired electrician
There is no code rule that covers that, but there is some guidance in Table B.2(8) in Annex B.
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
As long as you maintain spacing -- that is, the cables are not touching each other -- you can have as many in a trench as you want.
ramsy
Roger Ruhle dba NoFixNoPay
- Location
- LA basin, CA
- Occupation
- Service Electrician 2020 NEC
How many have you installed like that?
Omitting ampacity derating guidance per Annex B. Table B.310.15(B)(2)(8), Detail 6.
Detail 1-10 are shown several pages below that table.
FIGURE B.310.15(B)(2)(2) Cable Installation Dimensions
Would you then agree that the only way to properly space these cables is using Annex B/ Neher-McGrath Calculations?
- Location
- Illinois
- Occupation
- retired electrician
In my opinion the Neher-McGrath calculations are the only way to correctly size and locate any underground system where the load has been calculated per engineering design and not Article 220. The Article 220 loads are so inflated, it probably won't make any difference.