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I need to drop some conduit in my crawlspace and run it under the brick skirting in order to install some conduit. Once outside the skirting, I plan to rent a trencher to do the majority of the run, but I'm having some trouble figuring out exactly how I can get from the crawlspace under the house to the trench I'll be cutting later. There isn't all that much room in the crawlspace - perhaps 36" vertical when positioned between the floor joists. Obviously the conventional posthole diggers (the powered kind) wouldn't work in this situation because of the lack of room to maneuver.

One thought I had was to use a garden bulb augur:

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However, some of the reviews of these that I read described people trying to use them to dig holes in a non-gardening application like mine. Those reviews indicated that either the augurs or the drivers used to power them may strip or otherwise not be able successfully dig the hole.

Beyond this, I haven't thought of many alternatives.

Update: I tried the bulb augur idea and discovered, somewhat embarrassingly, that the brick skirting extends down below the surface at least 18" and very probably a good bit more than that. Busting out subterranean masonry under the foundation of a house is a bad idea, even if I could do it (and I'm pretty sure I can't).

@Craig's answer was right: I'm going to use an LB and run the fiber out the same hole being used by an outdoor power outlet. The fiber is a multimode 50/125 OM3. The bend radius is unspecified in the documentation for the cable, so I've contacted Tripp Lite's support to get that information. In the meantime, I found a comparable cable with a long-term radius of 5cm, and the LB will allow for that.

Also, on the augur itself: it performed admirably. I didn't have any trouble digging the hole it claims to be able to dig. It did bend at the chuck somewhat when I tried to ram it into the underground masonry, but that's pretty stiff abuse and I wouldn't expect it to do better than it did. Also, using a hammer driver was pretty important too, or the augur bit might have stripped.

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  • What is the conduit for, plumbing , electrical? I would just drill through the brick and 90 down(Use an LB if electrical conduit). Digging under the footer will cause cracks in the brick mortor to form later.
    – Brian Duke
    Nov 28, 2014 at 23:44
  • @user3623501 it's for fiber optic cable.
    – Ben Collins
    Nov 28, 2014 at 23:47
  • An LB would probably exceed the maximum bending radius of the cable, perhaps go through the brick into the top back of a PVC electrical box, something like 6x6x4, then straight out the bottom into ground. You could always paint the box and conduit to match the brick.
    – Brian Duke
    Nov 28, 2014 at 23:53
  • That's not a terrible idea. My main reason for wanting to get underground from the crawlspace was to protect the entry from moisture and critters and whatnot as much as possible. I guess I could achieve the same thing by making sure the conduit is sealed up well
    – Ben Collins
    Nov 29, 2014 at 0:59
  • Step one in figuring out what can work is to sort the minimum bend radius of the cable - if not purchased yet, reduced-bend radius fiber cable can make installation a whole lot less fuss (for surprisingly little upcharge in many cases - like a nickel a meter for 12 fibers.) Voice of Experience here - a bunch of annoying 6x6x4 boxes we might have needed turned into 1" LBs with RBR cable. Most FTTH cable is now RBR cable - ask your provider if that's your situation.
    – Ecnerwal
    Nov 29, 2014 at 17:45

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Good old blood, sweat and tears, maybe? No, seriously... ;-)

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If you can dig a hole on both sides, inside and outside the crawlspace, maybe you could use that auger with the drill to punch a hole through to connect the holes, then run your conduit.

You could also potentially "drill" the hole with pressurized water, but that's less than desirable in your crawlspace.

I would certainly minimize the amount of excavation directly under the footing.

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An electric chipping hammer makes short work of difficult soil removal in tight spaces. It can also chip rough holes through masonry.

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    My normal tool buying philosophy: if it will be used rarely then get a cheapo one (they have them at Harbor Freight). If it is a tool you will use frequently, spend the money on a good one (preferably made in the U.S.A.).
    – Jimmy Fix-it
    Nov 29, 2014 at 22:34

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