caryseidner Posted November 22, 2009 Report Posted November 22, 2009 If the grading would have been a little higher I never would have noticed this. I'm certain this is wrong and a safety concern. Are the exposed conductors only supposed to be covered by grade, or should the conduit have been extended to a particular depth? Click to Enlarge 96.56 KB Click to Enlarge 75 KB
Jim Katen Posted November 22, 2009 Report Posted November 22, 2009 If the grading would have been a little higher I never would have noticed this. I'm certain this is wrong and safety concern. Are the exposed conductors only supposed to be covered by grade, or should the conduit have been extended to a particular depth? The conduit is supposed to be extended to the required burial depth for those conductors in that location. (300.5). From what I can see in your picture, that would be 24" deep in this case. - Jim Katen, Oregon
caryseidner Posted November 22, 2009 Author Report Posted November 22, 2009 Jim, The conductors are copper 3/0. The (300.5) is the NEC?
Jim Katen Posted November 22, 2009 Report Posted November 22, 2009 Jim, The conductors are copper 3/0. Is the (300.5) is the NEC? Yes. That's the article that deals with Underground wiring. It includes a nifty table that shows how deeply different sorts of electrical things are supposed to be buried. For instance, with your direct burial conductors, you're supposed to have 24" of soil cover over them in most locations. If you have a 2"-thick concrete slab over them, you only need 18" of cover. If you put them under a building, they don't need any cover, but they have to be in a raceway. It's a handy table. So, 300.5(D)(1) actually says: Direct-buried conductors and cables emerging from grade and specified in columns 1 and 4 of Table 300.5 shall be protected by enclosures or raceways extending from the minimum cover distance below grade required by 300.5(A) to a point at least 8 feet above finished grade. In no case shall the protection be required to exceed 18" below finished grade. So my memory was faulty. The required burial depth is 24" but the conduit only needs to extend down 18". Getting sloppy . . . - Jim Katen, Oregon
caryseidner Posted November 22, 2009 Author Report Posted November 22, 2009 Jim, The conductors are copper 3/0. Is the (300.5) is the NEC? Getting sloppy . . . - Jim Katen, Oregon Thank you sir. Gotta get me one of those NEC books. I'll take a sloppy Jim Katen any day!
Jim Katen Posted November 22, 2009 Report Posted November 22, 2009 On a related note, I've seen three of these so far this year. The homes were from 1970, 1972, & 1973. I cringe to think about how many I've missed over the years. - Jim Katen, Oregon Download Attachment: IMG_1319 (Large).JPG 155.38 KB Download Attachment: IMG_3382 (Large).JPG 177.16 KB
Brandon Whitmore Posted November 22, 2009 Report Posted November 22, 2009 My last 70's home I inspected had the same rusted out conduit-- see it way too often. I always assume that the conduit is just rusted out-- it may be a rusted bottom edge but I've never dug down to find out.
kurt Posted November 22, 2009 Report Posted November 22, 2009 You always note the presence or absence of a "sleeved" conduit, don't you? That's one of the things that cost me a few grand several years ago.
gtblum Posted November 22, 2009 Report Posted November 22, 2009 Here's how I found out about a rotted one last month. The SEC was on the pole at the street and, the conduit disappeared at the bottom of the pole. It was the only one in the neighborhood like that. It won't be now. Click to Enlarge 42.63 KB
Jeff Remas Posted November 22, 2009 Report Posted November 22, 2009 This is the #1 reason I like PVC and slip risers.
Billy_Bob Posted November 22, 2009 Report Posted November 22, 2009 Also common sense prevails with something like this. Imagine one of those weed whackers going to work on that. Or more specifically a weed whacker which has blades rather than string. The insulation could be easily removed. Then the family dog comes along and gets zapped via the nose or other end by marking his territory. Or a small boy with a metal stick going along walls or fences banging/poking on things.
kurt Posted November 22, 2009 Report Posted November 22, 2009 This is the #1 reason I like PVC and slip risers. Slip risers. I've always called it movable sleeve because no one knew what to call it. Is slip riser referenced in the NEC?
Bill Kibbel Posted November 22, 2009 Report Posted November 22, 2009 Slip risers. I've always called it movable sleeve because no one knew what to call it.Is slip riser referenced in the NEC? I think it's called a "slip joint" on the meter riser. I also think there's a requirement in the NEC as of '02. The local POCos here require it as well, but don't always notice if it's omitted.
Jim Katen Posted November 23, 2009 Report Posted November 23, 2009 Slip risers. I've always called it movable sleeve because no one knew what to call it.Is slip riser referenced in the NEC? I think it's called a "slip joint" on the meter riser. I also think there's a requirement in the NEC as of '02. The local POCos here require it as well, but don't always notice if it's omitted. I don't know of any specific requirement for a slip joint. But 300.5(J) dates back to the '96 edition and it requires that "where subject to movement by settlement or frost, conductors, raceways, & cables have to be "arranged to prevent damage to the enclosed conductors or to equipment connected to the raceways." With conduit, I think that pretty much equals an expansion joint, slip joint/riser, sleeve, or whatever you want to call it. Pre-'96, I'm not aware of any such requirement and I've never see one used then. - Jim Katen, Oregon
Jeff Remas Posted November 23, 2009 Report Posted November 23, 2009 As Jim stated, 300.5(J) covers this issue. This is from one of our our local POCOs: http://inspectpa.com/download/slipriser.pdf
Marc Posted November 23, 2009 Report Posted November 23, 2009 But what about the conductors? They can't stretch.
Jim Katen Posted November 23, 2009 Report Posted November 23, 2009 But what about the conductors? They can't stretch. The installer is *supposed* to provide an "s" loop in the conductors in the trench just before they enter the conduit (if they're direct buried). If they're completely in conduit, there should be a provision for some flexibility at each connection point. - Jim Katen, Oregon
Jim Katen Posted November 23, 2009 Report Posted November 23, 2009 As Jim stated, 300.5(J) covers this issue. This is from one of our our local POCOs: http://inspectpa.com/download/slipriser.pdf Jeff, Do any of your POCOs require a steel ell in that location? We've had issues here where the string cuts through the PVC as it goes around the corner while pulling those fat service cables. - Jim Katen, Oregon
Jeff Remas Posted November 23, 2009 Report Posted November 23, 2009 As Jim stated, 300.5(J) covers this issue. This is from one of our our local POCOs: http://inspectpa.com/download/slipriser.pdf Jeff, Do any of your POCOs require a steel ell in that location? We've had issues here where the string cuts through the PVC as it goes around the corner while pulling those fat service cables. - Jim Katen, Oregon No, not for residential but I do see them for commercial at the base of the poles that the conductors run down. The problem is that everyone transitions to PVC and they always separate there so at the base of every pole (XFMR on pole, not pad mounted) there is always a gap with the conductors on the secondary exposed.
Erby Posted November 23, 2009 Report Posted November 23, 2009 With all the hills we build on around here, I see the pulled away conduit at either the meter box or ground level quite a bit. Last one I heard a cost on was about $700.00 to fix.
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