EMT couplings - what would you specify?

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steve66

steve66

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Illinois
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Engineer
Seems like there are several choices for EMT couplings. Are they all good, or are some of them junk? What would you specify or use if it were your project?? Assume the customer is willing to pay for quality, but doesn't have money to burn.

The choices include set-screw or compression couplings in either steel, die-cast zinc, or maellable iron. (I assume couplings are available in the maellable iron, since it is a box we can check in speclink.)

Steve
 
I agree with bdarnell,

I always use the steel fittings they seem to hold up better. The cast fittings seem to split and break much easier.

JMHO, Chris
 
Steel set-screw. Forget compression of any type above 1 1/2". They're difficult to tighten properly. A few years ago there was an article in, I believe, EC&M regarding conduits following an earthquake in California. The only conduits that were still together had steel set-screw fittings.
 
We don't have many earthquakes here, but I'll keep that in mind. :)

I have heard that the maellable iron is for conduit bodies only, and couplings only come in steel or die cast metal.

Steve
 
"Steel set-screw. Forget compression of any type above 1 1/2". They're difficult to tighten properly"


chain wrench, pipe wrench, strap wrench, channel lock 440's, channel lock 460's. gets routine in a short time. we dont use set screw on bigger pipe and never a problem after all these years. a properly seated compression fitting thats tightened properly is not coming apart. and thats with 600 kcmil in a back to back 4 inch.
 
crankshaft said:
"Steel set-screw. Forget compression of any type above 1 1/2". They're difficult to tighten properly"


chain wrench, pipe wrench, strap wrench, channel lock 440's, channel lock 460's. gets routine in a short time. we dont use set screw on bigger pipe and never a problem after all these years. a properly seated compression fitting thats tightened properly is not coming apart. and thats with 600 kcmil in a back to back 4 inch.
Click to expand...


Problem is, if you have a rack of large conduits spaced an inch or so apart it's nearly impossible to get any of the tools that you mentioned in there to tighten them.
 
Many commerical specs require compression.
I like steel setscrew or compression.
steel compression looks best in exposed runs
Studies done by UofGA show that setscrew have best fault clearing.
And the diecast with a square drive tighten up really well with a battery drill.
Use the diecast if in a wall.
 
I also prefer steel fittings.
When I ask for compression fittings at the supply house, they always bring me the Raintight variety, with the O-ring. As these are a real pain in the neck to use, I shy away from them on indoor installations and stick with set-screw. It's been my understanding that all compression fittings now are "raintight", with the o-ring. If someone is still making the old style compression fittings, I'd like to know about it.

John
 
My preference is steel setscrew, however my van is loaded with steel compression, because a few of our customers want them and I'd rather carry one type on my van and not load it down with four different types of each fitting.
 
The steel seems to hold up better through a few re-dos when the plans are shall we say..."fluid". For something that's not going to change tomorrow, I'd have no problem with zinc.
 
I like the set screw couplings, but they can be problem on long runs when you want to use a vacuum fish tape system. Too much air leakage to make the system work. That may not still be true as my assignment for the last 11 years only permits the use of real conduit...rigid. :twisted:
Don
 
don_resqcapt19 said:
I like the set screw couplings, but they can be problem on long runs when you want to use a vacuum fish tape system. Too much air leakage to make the system work. That may not still be true as my assignment for the last 11 years only permits the use of real conduit...rigid. :twisted:
Don
Click to expand...

You're right about that Don. Nothing like having to go around and duct tape the couplings to get a drag and true tape through the conduit.

11 years of rigid, how's your back? Years ago we did a job where we installed 5000' of 4" RMC. My back hurts just thinking about it. :wink:
 
Trevor

Years ago we did a job where we installed 5000' of 4" RMC. My back hurts just thinking about it.
Click to expand...

Whine, whine! :p :p

I know how you feel. When I started my apprenticeship, we didn't have the neat tools to work with like we do now. I didn't run anything over 3 1/2" RMC, but we used an extension ladder to get up to the trusses, pulled a pic up to place between the trusses, pulled the conduit up with a rope and went to work. This always occurred in the summer months. Hot, dirty, heavy, slow work. It is a good thing we don't do things that way anymore. I couldn't handle it. My back would start aching. :D
 
infinity said:
crankshaft said:
"Steel set-screw. Forget compression of any type above 1 1/2". They're difficult to tighten properly"


chain wrench, pipe wrench, strap wrench, channel lock 440's, channel lock 460's. gets routine in a short time. we dont use set screw on bigger pipe and never a problem after all these years. a properly seated compression fitting thats tightened properly is not coming apart. and thats with 600 kcmil in a back to back 4 inch.
Click to expand...


Problem is, if you have a rack of large conduits spaced an inch or so apart it's nearly impossible to get any of the tools that you mentioned in there to tighten them.
Click to expand...

tighten fittings as you put the lengths up. 99.9 percent of the time your gonna install a rack with many conduits on them. thats not a reason to use set screw. as don stated, going around and having to tape every coupling, now thats a pain in the ass with a rack full of pipe and 1 inch spacing. put a stick up, tighten the compression fitting and then another stick on the rack.
 
If the couplings are right next to each, meaning not staggered, than the space between them is probably close to 1/2". Not really enough room to insert a chain wrench etc. to properly tighten them.
 
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