Why did the cable cross UNDER the sidewalk?

To get to the other side of course.

Actually, I'm going to deal here with the how and not the why.
Someone posted a question recently. Anonymous asked:

Hey Gregg, How do you get a wire under a sidewalk?


Now, I'm thinking this might be kind of an inside joke, because an online discussion group in which I participate with fellow outdoor lighting designers and contractors has gone through at least three cycles of posts regarding this topic in the 5 years I've been participating.

So Kevin, Mike or John.. or maybe James... you'd better pay attention :-)

But assuming this is a serious question, posed by someone with a dire need to know, II'll share what I can.

First, why do you want to get the wire to one side of the sidewalk to the other? And is this a public sidewalk or a walk within the boundaries of your own or a paying customer's property?

Whether pipes or wires, you have two choices to get from one side to the other: boring or cutting. I don't advise cutting through public sidewalks, but boring under one is fine.

Be careful about utility locations. The best thing to do is to call Underground Service Alert at least 2 days ahead of time and let them take care of marking sewer, water, gas and electrical lines before any digging, boring or trenching.

When you're dealing with walks on private property you might have more options. Are there wooden boards or bricks set in the concrete at intervals as expansion joints? Are they old, loose or rotten, or could they otherwise stand to be removed and replaced? If so you've just saved yourself some work.

Getting a pipe or wire under a sidewalk is one of those things where various individuals come up with methods that suit them and then stick with them... and hold strong opinions about why their method is best.

I've seen or heard of everything from a sledge hammer and a capped piece of galvanized pipe, to electric or gas powered drilling machines, to pneumatic piston-like devices that punch through the soil. Frankly, for a sidewalk, I think simpler is better.

The simplest method is a combination of a piece of pipe, (a couple of feet longer than your bore), with a tapered nozzle at one end and female hose fitting at the other. I like a ball valve or gate valve on the hose fitting end of the pipe too. All that's involved is digging an approach trench longer than your pipe, and deep enough that your pipe is level while passing under the walk. Then attach a hose, turn on the water, and start poking the nozzle end of that pipe in the direction you want.

Did I mention you should have on clothes that you don't mind getting muddy? And waterproof footwear... and maybe knee pads and gloves too? And how about a towel for when that mud splashes back in your face when you're trying to position the nozzle with the valve opened up?

After you've done this once it's pretty simple. You get a feel for when to hold the pipe still and let a little water do the work, vs. how hard or fast you need to push. Of course soils will vary. Some are rocky, some are more sand, silt or clay. I've never run into one I couldn't bore through, but sometimes it takes a little more time and effort.

Rocks, roots and other unforeseen obstacles can be problematic. You may have to change course or start a new bore if you run into something too solid.

Once the pipe has passed through, tie a heavy string line to the nozzle end and pass it back through the bore you made. Then use that line to pull your pipe or cable back through the bore. It's easier than it sounds.

And if you get in over your head (let's hope you don't have to go that deep) then just give us a call.

BTW, the very best way to get a wire or pipe under a walk is to plan ahead and install a large diameter sleeve before the concrete is poured (3" PVC drain pipe works well) and let it extend 12" beyond the forms on each side. You can always shorten it later. The more sleeves the better. Cap them and mark them with flags or tape for future needs.

A sleeve allows some flexing of the pipe or cable inside, during an earthquake for instance, or from expansion or contraction due to temperature changes.