Securing EMT to lolly column

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iwirehouses

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Hey, I got a question. What would be all of your preferred methods of securing EMT to a lolly column. Drill and anchor the strap? My father suggested hose clamps but hes a carpenter and he also knows the inspectors well. I know hose clamps are not UL listed for this. I started thinking that zip ties ared allowed by the NEC for Romex, but nowhere in the NEC could I find exactly what to use for EMT.
 
HAHA. I know that it wouldn't matter at all, but I was just thinking leave the concrete in the lolly column alone and fasten it some other way. Though drilling it is the only reasonable way I guess.
 
Can you do back to back cowboys/mineralacs? Get a couple that will fit snugly around the lolly column and a couple that will fit the conduit size you need to secure. Bolt the two mineralacs together and you're done. No drilling involved. It ain't the prettiest way to do it but it'll git er done. I've done it the ramset way too. If you go that route make sure there's nobody anywhere nearby when you pull that trigger. Shooting into a round column might be a little dicey, though I've never had a problem with it.
 
You can drill and tap it or you can cut some strut and use threaded rod to pancake the column then use strut straps, seems kind of involved but its the only way when the column is concrete filled.
 
I have done this many times and the back to back cowboys/mineralacs is IMO the best way. it does not sacrifice the integrity of the column and its strong. You could do chin up on you pipe if it were on the ceiling. In addition to this you don't need to bend and offset since its space out.
 
hardworkingstiff said:
I sure hate to show my ignorance, but what is a "lolly column"?
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It's actually "lally", and it's a steel pipe filled with concrete. This gives it incredible compressive strength for weight bearing.
 
I would use a #10-1/2" hex head, self drilling sheet metal screw AND an impact driver. Taka-taka-taka...
Simple and elegant. If you don't have an impact driver, this is your excuse to get one.
~Peter
 
hardworkingstiff said:
Thanks Larry. Would this normally be in the 3" - 4" diameter range?
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You're welcome, and yes, that's a common diameter range. Another thing about lally columns is that they can be cut to length, and end plates added.
 
peter said:
I would use a #10-1/2" hex head, self drilling sheet metal screw AND an impact driver. Taka-taka-taka...
Simple and elegant. If you don't have an impact driver, this is your excuse to get one.
~Peter
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I've not tried putting a TEK screw tip into concrete. Does this work?
 
hardworkingstiff said:
I've not tried putting a TEK screw tip into concrete. Does this work?
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In my experience it works for about the first revolution in the concrete (if it really is concrete and not just masonry cement). I've not tried it with an impact driver. I don't see how a so-called impact driver is going to aid in the drilling of concrete as it is uses radial impact for tightening and loosening. I use a rotary hammer. It too is an impact driver, but the impacting is axial.

I have used self-drilling, self-tapping screws after drilling the metal until the drill tip just pierces the metal jacket, switch to an impact-driver (hammer drill, rotary hammer, etc.) to add depth to the hole—with a percussion masonry bit, not the screw—then fasten with the same sd/st screw I started the hole with.

I have also used tapcons (or the equivalent). Pretty much the same method as sd/st screws except drilling a hole slightly oversized in the metal jacket. I have a 3-function SDS Plus rotary hammer (i.e. impact-only, drill-only, and impact drill) setup with both a standard chuck on an SDS Plus adapter and an SDS Plus-converted Con Driver... making bit and driver changes easy and fast. Then fun part is when I forget to switch to drill-only mode :grin:

...but I only use the foregoing methods if a powder-actuated fastening system is not readily available :grin:

The mineralac-type conduit hangar method is also OK, but I tend to stay away from it for in-public-view areas.
 
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hardworkingstiff said:
I sure hate to show my ignorance, but what is a "lolly column"?
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Perhaps I should clarify.
My impression of lally columns is that they are steel pipe perhaps 3/17" thick and then filled with concrete. I specified 1/2" length since the threads would only need to engage that outer, 3/17" layer of steel. Also some thickness is taken up by the thickness of thy one hole straps or Minnie conduit hanger.

Steel backed with concrete is a tough nut. You use a metal drill bit for the steel and, as soon as it hits the concrete, it becomes dull. Powder activated fasteners might work but they might crack the concrete within. Perhaps drill the hole to 1/8" and then use a pop rivit. A nice thing about self drilling screws is that they are very cheap, disposable drill bits.
~Peter
 
peter said:
Powder activated fasteners might work but they might crack the concrete within.
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"MIGHT", as in "may", is right next to "IF" in my dictionary. When shooting directly into concrete a very, very low percentage cause the concrete to crack, and the ones that do are usually close to an edge or in low psi concrete. Besides, I'm guessing that a majority of the shot's retention characteristics are from the steel.
 
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