Parallel Direct buried cables

arnettda

Senior Member
Can I parallel 2 sets of say 4/0 4/0 2/0 cables and run them together in the same trench but come up into the equipment on both ends in seperate pipes? I will include a fourth conductor.
 

Smart $

Esteemed Member
Location
Ohio
Can I parallel 2 sets of say 4/0 4/0 2/0 cables and run them together in the same trench but come up into the equipment on both ends in seperate pipes? I will include a fourth conductor.
Yes, you can. If only four total are current-carrying, you do not have to derate the ampacity for the number of conductors: 310.15(B)(3)(a)(3)...

Adjustment factors shall not apply to underground
conductors entering or leaving an outdoor trench if those
conductors have physical protection in the form of rigid
metal conduit, intermediate metal conduit, rigid polyvinyl
chloride conduit (PVC), or reinforced thermosetting resin
conduit (RTRC)
having a length not exceeding 3.05 m
(10 ft), and if the number of conductors does not exceed
four.
[Edit to add] Note the trench must be outdoors.


However, if by "include a fourth conductor", you mean an EGC... I believe a full-sized EGC per cable-pipe run is required.
 
Last edited:

arnettda

Senior Member
Yes, you can. If only four total are current-carrying, you do not have to derate the ampacity for the number of conductors: 310.15(B)(3)(a)(3)...



[Edit to add] Note the trench must be outdoors.


However, if by "include a fourth conductor", you mean an EGC... I believe a full-sized EGC per cable-pipe run is required.
310.15(B)(3)(a) Talks about without maintaining spacing what distance is considered spacing?
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
I was just going to lay it in the trench with the cable.
In general 300.3(B) requires the EGC to be in the same cable as the circuit conductors. 300.3(B)(3) may permit you to install it in the same trench with the power cable assuming a non-ferrous cable jacket.
 

Smart $

Esteemed Member
Location
Ohio
In general 300.3(B) requires the EGC to be in the same cable as the circuit conductors. 300.3(B)(3) may permit you to install it in the same trench with the power cable assuming a non-ferrous cable jacket.
But what about where the cables emerge in conduit? Parallel cables, parallel conduits, parallel EGC's...???
 
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