Multiple Conduits in Trench

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peter

Senior Member
Location
San Diego
Yes, you can have more than one conduit in a trench. Why not.
Are you going to dig a separate trench for each conduit.

Yes. They make various forms of devices for mounting conduits in trenchs. But these are generally used when there are large numbers of conduits. With two 2" CONDUITS, JUST TOSS 'EM IN. mAKE SURE THEY'RE DEEP ENOUGH.
~Peter
 

tkb

Senior Member
Location
MA
When you bury them, it is no longer a trench.
Yes, conduits can be buried in the same planet. ;)
 

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
Our inspector makes us leave a gap between conduits. I usually just drive pieces of 1/2" emt between them every so often.
 

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
Can two 2 inch PVC conduit lay side by side, or over and under, in the same trench?
Is there a racking system available for underground conduit installation?

If it is utility trench then they may have their own requirements.
 

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
Why the ???

Because I looked and looked but couldn't find the section. :confused: :confused: :confused:

Now that i found it, could someone explain why the conduit have to have separation besides of the obvious. (the conduit need separation on so the locknuts, grounding bushings and like will fit) Other than that why would you require separation between conduits.

Since this requirement is in 310.15(B)(3)(B) i assume it is for derating. But derating of conductors if they are in separate conduits???

I am very glad that i am learning something new.
 

tkb

Senior Member
Location
MA
Because I looked and looked but couldn't find the section. :confused: :confused: :confused:

Now that i found it, could someone explain why the conduit have to have separation besides of the obvious. (the conduit need separation on so the locknuts, grounding bushings and like will fit) Other than that why would you require separation between conduits.

Since this requirement is in 310.15(B)(3)(B) i assume it is for derating. But derating of conductors if they are in separate conduits???

I am very glad that i am learning something new.

I just reread 310.15(B)(3)(a) and (b).

310.15(B)(3) is titled "Adjustment Factors"

(b) only says to maintain spacing with NECH comentary,

Spacing is normally maintained between individual conduits in groups of conduit runs from junction box to junction boxbecause of the need to separate the conduits where they enter the junction box, to allow room for locknuts and bushings.



(a) applies to cables and conductors and states that derating needs to be applied if run for 24" or more. This is the bundling rule.

I am now confused, (b) seems to be just a statement that spacing needs to be maintained between conduits but no direction or reference when spacing is not maintained.
I think it should reference (a).

(b) seems to be nothing but a suggestion.
 

paulgarett

Member
Location
San Rafael, CA
Thanks for the responses. Here is another question for j-box sizing.

Following NEC 314, sizing boxes: If two 2 inch PVC pipes enter a underground j-box or "Christie Box" and two 2 inch pipes leave the other side, what box sizing guidelines should be followed? Angle Pull? Straight Pull?
 

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
If I run two conduits tight together for 100' the spacing has been maintained.;)

We often joke about sliding toothpicks between them, but I don't think the inspector would find it funny....he can be a real buzzkill!:grin:

In all seriousness, I believe the inspectors viewpoint on it is that he thinks the conduits/wire will heat up and melt down if you rack them all tight.
 

chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
Following NEC 314, sizing boxes: If two 2 inch PVC pipes enter a underground j-box or "Christie Box" and two 2 inch pipes leave the other side, what box sizing guidelines should be followed? Angle Pull? Straight Pull?

If you 90'ing up into the bottom of a hand hole, see 314.28(A)(2) exception.
 
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