Running RMC, techniques

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jumper

jumper

Senior Member
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3 Hr 2 Min from Winged Horses
LarryFine said:
Last year, I ran two 2" RMC runs up the outside of an approximately-100'-tall apartment building for a roof-mounted cellular site. The only Eriksons I used were at the very bottom, where they joined two existing-but-abandoned RMC's from the old service entrance. See thumbs:

The guy who hired me ran his 1-1/4" RMC using non-threaded compression couplings at every cut. Looked really amateurish in comparison, if I may say so.
Click to expand...

Missing conduit straps in pic #1.
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
LarryFine said:
The guy who hired me ran his 1-1/4" RMC using non-threaded compression couplings at every cut. Looked really amateurish in comparison, if I may say so.
Click to expand...

A have only ever used the set screw type box connectors (for rigid). I remember they were quite pricey. I imagine the compression ones are just as bad if not worse. I remember pricing out a 20 foot service riser and comparing EMT to RGS. It was 4 inch I think. By the time you buy the meyers and all the (stupid) raintight EMT fittings, the EMT was still cheaper, but not by much. Just saying the cost of these specialty fittings is definitely worth thinking about.
 
A

AKElectrician

Senior Member
Location
Soldotna, AK, USA
LarryFine said:
Last year, I ran two 2" RMC runs up the outside of an approximately-100'-tall apartment building for a roof-mounted cellular site. The only Eriksons I used were at the very bottom, where they joined two existing-but-abandoned RMC's from the old service entrance. See thumbs:

The guy who hired me ran his 1-1/4" RMC using non-threaded compression couplings at every cut. Looked really amateurish in comparison, if I may say so.
Click to expand...

Ill beat you all to it and say my comments below are my opinions and the suggestions are completely unnecessary. I know but tell that to the monsters that created me, they were ruthless.

I would have at the very least hid the unions and RE with the Pull C's I am guessing are barely seen in pic 1, also would have used the left RE on the right might have been closer matching tops out the gate. I also would have bent it all in a single piece, if anyone's getting paid to bend pipe might as well be me. Plus the savings in couplings alone, not to mention they'd all line up in a row. Also wouldn't have had to fight that strap in the middle of pic 1. Unless you used a saddle strap instead of a two piece, even then it wasn't even with the other, and did you stack something on top the middle coupling in pic1?

But you did put the unions the right way...
 
jumper

jumper

Senior Member
Location
3 Hr 2 Min from Winged Horses
AKElectrician said:
Ill beat you all to it and say my comments below are my opinions and the suggestions are completely unnecessary. I know but tell that to the monsters that created me, they were ruthless.

I would have at the very least hid the unions and RE with the Pull C's I am guessing are barely seen in pic 1, also would have used the left RE on the right might have been closer matching tops out the gate. I also would have bent it all in a single piece, if anyone's getting paid to bend pipe might as well be me. Plus the savings in couplings alone, not to mention they'd all line up in a row. Also wouldn't have had to fight that strap in the middle of pic 1. Unless you used a saddle strap instead of a two piece, even then it wasn't even with the other, and did you stack something on top the middle coupling in pic1?

But you did put the unions the right way...
Click to expand...

Okay......of which none that I can see would be required by code.:cool:
 
LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
AKElectrician said:
I would have at the very least hid the unions and RE with the Pull C's I am guessing are barely seen in pic 1, also would have used the left RE on the right might have been closer matching tops out the gate.
Click to expand...

I did that to bring the conduits closer to each other, and the C's are where they are to be roughly in the middle of the greater-than-360-degrees in the entire run, and to minimize their appearance by being aligned with the bump-out in the wall.

I also would have bent it all in a single piece, if anyone's getting paid to bend pipe might as well be me.
Click to expand...

With the bump-out, it would have been difficult to bend the various angles in a single piece, and the separate 22.5-degree elbows allowed me to manipulate the conduits after assembly to hug the struts more easily.

Plus the savings in couplings alone, not to mention they'd all line up in a row.
Click to expand...

This is in an alley, and mostly against the fire escape, so appearance wasn't paramount to the installation. I actually started the conduits at the roof and worked my way down, so the couplings do line up the rest of the way.

Also wouldn't have had to fight that strap in the middle of pic 1. Unless you used a saddle strap instead of a two piece, even then it wasn't even with the other, and did you stack something on top the middle coupling in pic1?
Click to expand...

There was no struggle because I used a 2-piece strap a size larger around the coupling. The left pipe actually has two couplings with a close nipple between them to maintain the pipe spacing through the S-bends.

But you did put the unions the right way...
Click to expand...

Thank goodness you found one thing I did correctly! :roll:
 
LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Here are a few more pics which might help explain how and why I did it this way.

160429_003.jpg 160429_005.jpg 160504_005.jpg 160504_003.jpg

The left pic obviously shows the C-bodies, which are perched on the face of the bump-out. They're there because of the bends in the run:

Starting at the top, there are 90's pointing down toward the roof where the conduits pass over the top the 5'-tall outer wall, 45's where the conduits pass around the 4'-wide overhang, 90's around that overhang, and 45's where those return to the wall to point downward. The offsets bring the total to 360 degrees, but toting the conductors to the roof and pulling downward made the pull almost effortless.

Below the C-bodies, there is the second pair of offsets and the 90's in the old conduits where they turn horizontal against the basement ceiling. At this point, the power and ground-bearing conduits part company. The power conduit has one 90 in the basement where it turns toward the meter stack (perpendicular to the outside wall), and one more 90 where the conduit turns down into the top of the meter stack.

The conduit with the ground conductor reduces down to 1-1/4" EMT, has another offset and one more C-body, then continues toward the center of the basement with a couple of more bends, and terminates at the building's main water pipe. Of course, the grounding conductor is bonded to the conduit at both ends with bonding bushings, as is the EGC run with the power conductors. Everything is copper per the specs.

I started by assembling the 45's, the 90's, and the 45's at the top and clamping them to the wall. Then I passed a nylon rope with a hook attached (see left pic above) through the assemblies, where helper #1 passed them through each section of pipe and hooked them to the bottom end, I pulled each on up from the roof, and helper #2 screwed it onto the pipe above, and installed one or two strut clamps.

This method worked well because helper #2 didn't have to support the weight of each section of conduit while screwing it to the one above, and each pull was shorter than the previous one as we grew more tired. We alternated left and right so we didn't have to work our way down twice, and it was easier to do the cutting-and-threading work (the final pipe connections) near ground level instead of 90+ feet in the air.

The pulls were so easy, one getting the tips of the wires past the bends at the top, that we didn't even need to use the C-bodies for the pulling. In fact, we had to fight gravity near the finish, and I installed wedges to minimize the pull of the weight of the wire on the terminations. And, yes, we did attach the conduits and the disconnect to the face of the wall with strut and hardware before we were done.
 
LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
AKElectrician said:
I just have to ask did you only use factory bent pipes?
Click to expand...

Above joke aside, yes, my only bends were made with 90's. 45's, and 22.5's. It was faster, more accurate, and more flexible (as in adjustable) than 1-piece bending for the offsets and pathways I needed to follow, and I don't own a large-diameter bender.

I don't understand why this point is being made into such a big deal here. Imagine how difficult it would have been to make the 3-dimensional offsets I needed to both get out from behind the fire escape and clear the concrete projection I had to go around.

Plus, I still needed the C-bodies between the pairs of offsets to comply with the 360-degrees-between-pull-points limit. The time it would have taken to calculate, bend, and tweak the conduits far outweighed the materials cost, in my ever-so-humble opinion.
 
Besoeker

Besoeker

Senior Member
Location
UK
sw_ross said:
Looking at a job that looks like it would require running some RMC.
I'm just a small one man operation so I don't own mechanical benders and threaders, etc, and can't justify buying the equipment just to do this job.

I've priced out pre-made threaded 90's and 45's as well as 10' sticks, but got visualizing the route in my head and was thinking I'll probably need to cut/shorten a piece of the RMC along the route.

Without a threader how would I join up this shorter piece?
Is there a Union of some sort that can be used to accomplish this joint?

This conduit would be for service conductors feeding the meter/Main.

Thanks!
Click to expand...
RMC? Rigid metal conduit?
We had a guy who could do the bends round his knee. Not seen it used here in decades though. We tend to use SWA PVC or XPLE for external runs.
 
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