compression

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C

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
I'm going with no. I know the Dematic conveyor company specs comp fittings on conveyor installs because they think it provides a better grounding path?? But I have a hunch that ss fittings are probably installed correctly more often than comp fittings that take channel locks to tighten.

Comp is great for sucking a string in though, but everything else is a PIA.
 
texassparky

texassparky

Member
Location
Dallas / Ft. Worth
Cow said:
But I have a hunch that ss fittings are probably installed correctly more often than comp fittings that take channel locks to tighten.
Click to expand...

Correction - 2 pair of channel locks / or 1 pair of channel locks and a crescent wrench :smile:

and yes that is the problem they are usually only installed with one pair of channel locks :smile:
 
D

Doug S.

Senior Member
Location
West Michigan
We're almost at an hour now, and no moderator to lock it up? :grin:

I prefer set screw personally, but have met those who feel strongly in opposition to my view.

I like the fact that the screw will pierce, or otherwise disturb any coating, or oxidation, or smutz that MIGHT some how inhibit a ground path. ( I still, with VERY few exceptions, pull in that green wire. )

My 2?
Doug S.
 
LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
I prefer the SS fittings. Compression fittings unscrew too easily. More than once, I've accidentally unscrewed a piece of EMT from a box connector inside a wall from above.

Luckily, the nut and compression ring didn't fall off, and I was able to get the tube back into the connector and tighten it back. I've never had that happen with SS fittings.
 
N

nakulak

Senior Member
I like compression fittings. I don't like the way set screws abnormally deflect the pipe, especially when a helper over tightens them. But I agree comprression fittings are often tightened improperly (as well as set screw )
 
masterinbama

masterinbama

Senior Member
Location
Huntsville Alabama
Cow said:
I'm going with no. I know the Dematic conveyor company specs comp fittings on conveyor installs because they think it provides a better grounding path?? But I have a hunch that ss fittings are probably installed correctly more often than comp fittings that take channel locks to tighten.

Comp is great for sucking a string in though, but everything else is a PIA.
Click to expand...

Is Dematic the ones that bend box offsets at every coupling? I installed some conveyors in a feed mill once that all of the factory EMT was offset at every coupling, looked neat but a waste of time in my opinion. We have since replaced that "tubing" with "real" conduit.
 
infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
There was a study done after a major earthquake and the fittings with the lowest failure rate were steel set screw type. Die cast fitting in either set screw or compression came apart or worse broke apart. Steel compression fittings also came apart.

I agree that if you're going to be sucking in lines with a vacuum then compression are better but when it comes to installation ease and strength than steel SS are superior. As far as grounding, steel set screw connectors are tested and listed for grounding so that really should not be an issue.
 
VUGear

VUGear

Member
Location
I-40, TN
nakulak said:
I don't like the way set screws abnormally deflect the pipe, especially when a helper over tightens them. But I agree comprression fittings are often tightened improperly (as well as set screw )
Click to expand...
That deflection, or flattening of the conduit, can make for less contact area.
 
S

SEO

Senior Member
Location
Michigan
All emt connectors have their place. I have not seen a set screw connector listed for use in a wet location. As with any installation the equipment has to be installed according to equipment listing. One thing that makes set screw conn and couplings preferable is sometimes during a walk-thru you can see a screw that has not been tightnened where as a compression conn or cpling it not as obvious.
 
daleuger

daleuger

Senior Member
Location
earth
Doug S. said:
We're almost at an hour now, and no moderator to lock it up? :grin:

I prefer set screw personally, but have met those who feel strongly in opposition to my view.

I like the fact that the screw will pierce, or otherwise disturb any coating, or oxidation, or smutz that MIGHT some how inhibit a ground path. ( I still, with VERY few exceptions, pull in that green wire. )

My 2?
Doug S.
Click to expand...


Exceptions....such as....
 
G

Goroon

Member
:confused::rolleyes::smile:
Had same question ask of me at shop one day ~ 2 years ago~ after 5 guys had gone to CEU Class for grounding -
Screw or compression? The instructor had said Screw was better ground connection. I said lets test it.
Set up a 3 KVA 480/240 and ran an old 1 ph compressor on it.
L1 secondary linked to 4ft 1/2 EMT with screw fitting. (on insulators)
L2 secondary linked to 4ft 1/2 EMT with compression fitting.(on insulators)
Had person 1 from each perspective make up own fitting.
IR Scan showed 3 times the heat on Compression.
Disassembled and found arching at compression contact point.
no noticable indication on screw fitting (More metal to metal Contact?)
I still use both, as stated each has its own use. Have fun,
 
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