Is there a requirement of a base for the PVC conduit to lay on in a underground service????> This base being sand or such?
Not nessarily a code thing, but may be required by your POCO spec's.
300.5 (F) requires "granular or selected material" (ie sand) if the fill contains rocks, paving chunks, etc.
On top of all that, many utilities require sand around the conduit. I know that PG&E here in CA requires 4" of fill that has all rocks under 1/2" dia. Their crews use sand for any work that they do.
Socal Edison requires sand for one conduit. Two conduits are to be partially encased, conduits laying on sand, concrete poured on top of them. 3-4 conduits are to be fully encased, concrete all around them.
I forget when you need to start seperating them, but I know if you have 8 conduits you have to split them into seperate trenches.
Ditto on checking with the PoCo!
Also, are you referring to "Cushions" used on Primary Feeder Ducts?
SCE (So. Cal. Edison) wanted Sand and Gravel Cushions on Primary Feeders - especially when Feeders came from Poles on Hills.
SCE did not require anything special for Secondary Feeders, unless the Soil is very "Rocky", then they want some Sand.
I have the currently used "ESR" Manual from SCE (Electrical Service Requirements Manual), which I use for assistance in designs/engineering projects. If needed, let me know some specifics and I can reply with quotes from the ESR.
Although it may not be exactly what your PoCo would specify, it might be somewhat relavent - just for an idea.
Scott35
SCE did not require anything special for Secondary Feeders, unless the Soil is very "Rocky", then they want some Sand.
Scott35, in all the work we have done for Edison the secondaries have the same requirements as primaries. This usually means more work on the secondaries on our projects since there are usually multiple conduits which require encasement. While the primary usually is a single conduit requiring just sand.
This post made me laugh, a feeder trench for a local auto dealer, was held up for days, because the utility inspector din't like the color of the sand, the engineer on the job was talking to himself.