The conduit must be below the roof line how low?

[Stan Elmin]

Does anyone have the specific code that tells exactly how far below the roof line the electrical conduit must be?
A link or any help would be deeply appreciated.

Thanks,
Stan

[inetdog]

Does anyone have the specific code that tells exactly how far below the roof line the electrical conduit must be?
A link or any help would be deeply appreciated.

Thanks,
Stan

In the 2011 NEC, try 300.4(D):
(D) Cables and Raceways Parallel to Framing Members and Furring Strips. In both exposed and concealed locations, where a cable- or raceway-type wiring method is installed parallel to framing members, such as joists, rafters, or studs, or is installed parallel to furring strips, the cable or raceway shall be installed and supported so that the nearest outside surface of the cable or raceway is not less than 32 mm (1-1⁄4 in.) from the nearest edge of the framing member or furring strips where nails or screws are likely to penetrate.
So when your conduit is running between the rafters and parallel to them, do not get closer than 1-1/4 inches to the roof decking. (This section does not actually specify that, but it complies with the safety intent of the section, which is to prevent roofing or framing nails added after the wiring is done from penetrating the cable or raceway (conduit).
The other section that is close is 300.4(E):

(E) Cables, Raceways, or Boxes Installed Under Roof Decking. A cable, raceway, or box installed in exposed or concealed locations under metal-corrugated sheet roof decking, shall be installed and supported so there is not less than 38 mm (1-1⁄2 in.) measured from the surface of the roof decking to the top of the cable, raceway,
or box.

For PV specifically, for DC circuits run inside the building below a roof, there is an additional requirement, 690.31(E). The restrictive parts of this only apply to DC wiring up to the first readily accessible disconnect. A disconnect on the roof itself will usually not be considered readily accessible. For those wire runs, except for the portion directly under the panels themselves, the wiring must be at least 10" below the roof decking to keep it from being cut/shorted by firefighters' saws when cutting holes in the roof.

Direct-Current Photovoltaic Source and Output Circuits Inside a Building. Where photovoltaic source or output circuits of a building-integrated or other photovoltaic system are run inside a building or structure, they shall be contained in metal raceways, or[...] or metal enclosures from the point of penetration of the surface of the building or structure to the first readily accessible disconnecting means.
The disconnecting means shall comply with 690.14(A), (B), and (D).
The wiring methods shall comply with the additional installation requirements in (1) through (4)
(1) Beneath Roofs
Wiring methods shall not be installed within 25 cm (10 in.) of the roof decking or sheathing except where directly below the roof surface covered by PV modules and associated equipment. Circuits shall be run perpendicular to the roof penetration point to supports a minimum of 25 cm (10 in.) below the roof decking.

Informational Note:The 25 cm (10 in.) requirement is to prevent accidental damage from saws used by fire fighters for roof ventilation during a structure fire.

In the 2014 code the requirement for a Rapid Shutdown Device on the roof or within 6' past the point where the wiring enters the building makes the spacing requirement for the wiring run after the RSD moot, but I am not sure whether the code officially recognizes that or not. (Can't find my copy of 2014 at the moment.)

[Stan Elmin]

Thanks for the info
much appreciated

stan