EMT Connectors and Ground-Faults.

[qcroanoke]

I will go with set screw. But really, neither one is any good if the locknut
is left loose.

 

[Jim W in Tampa]

Actually studies have shown that an EMT raceway has less impedance than a copper wire EGC.

So the "best way" is actually a mechanically sound raceway system.

Compression is my answer,assuming done right.Conduit itself is a great ground but connections start the problem.Add ground wire and i feel you have the best we can do.

 

[cschmid]

Actually studies have shown that an EMT raceway has less impedance than a copper wire EGC.

So the "best way" is actually a mechanically sound raceway system.

I have not seen the studies but could buy that if the EMT system stays mechanically stable..whisch over time and with the speed at which some contractors move the systems normally are flawed from the start..loose locknut's, hand tightened fittings, not supported properly for the application (yet still makes code), ect..yet I have seen them done properly and be 20 yrs old and still tight and useable..Just so you know I am not a cynic..

 

[Buck Parrish]

There is the real answer, it really depends on the quality of the fitting.

Yeah, Cast or forged metal fittings.
Some job specs. say "no cast fittings".

 

[paul]

Yeah, Cast or forged metal fittings.
Some job specs. say "no cast fittings".

Fine by me. Steel is less expensive nowadays than die-cast.

 

[jflynn]

What provides the best connection for for maintaining the Effective Ground-Fault Current Path when installing EMT?

Compression or Setscrew?

I would say S.S.,however I think the rate @ which S.S. fittings do not get secured may be more than compression.With compression,- we tend to make sure the fitting is secured before moving on...

 

[BryanMD]

I would say S.S.,however I think the rate @ which S.S. fittings do not get secured may be more than compression.With compression,- we tend to make sure the fitting is secured before moving on...

The extra cost of labor and material to use compression fittings where not needed can be cut to 25% (SWAG number) or maybe even less by the use of just a few more supports than code minimum may call for.

Properly supported and properly installed SS connectors will cost you less and will work just fine.

 

[LarryFine]

I vote setscrew. I've seen more compression connectors and couplings fallen apart than setscrew fittings.

Let's assume installed properly.

Oh, properly installed. In that case, I vote setscrew.

I also use steel connectors and couplings, not cast.

 

[jim dungar]

I believe there was a study performed, and compression couplings/connectors were the fittings that passed the most Ground Fault current.
I am too lazy to look, but I think that info can be found in Soares Book.

On page 136 of my 9th edition Soares book it describes testing done on over 300 conduit fittings. Only 7 sample assemblies did not pass their tests, with the primary failure being the "locknut to enclosure".

 

[M. D.]

I thought I came across an article ,..most likely EC&M where after a quake in California they found a bunch,,technical term ,..it means a lot , of compression connectors that pulled free compared to set screw.. I tried to find it but couldn't Does any one remember seeing it??

 

[frizbeedog]

I believe there was a study performed, and compression couplings/connectors were the fittings that passed the most Ground Fault current.
I am too lazy to look, but I think that info can be found in Soares Book.

Interesting. That information would be news to many based on the poll results so far.

 

[quogueelectric]

Interesting. That information would be news to many based on the poll results so far.

See I knew I was right. Sometimes I swim against the tide like a salmon.

 

[sparky59]

in my area steel compression fittings are the only thing allowed for egc.

 

[tmbrk]

Assuming both are made up correctly I would think the compression type has more serface area and would provide a better ground path.

The worst has to be indenter type fittings. I've run into them where I've pulled the pipe right out of the fitting (inside a wall.)

 

[M. D.]

See I knew I was right. Sometimes I swim against the tide like a salmon.

Hold on there Bessy ,.. I "believe" in the Easter Bunny ,..but I have yet to see the critter ..:smile:

 

[M. D.]

I think I found the study,.. damn computer won't open the pdf version
Let me know if this is it

http://www.steelconduit.org/pdf/groundingpart1.PDF

 

[Jim W in Tampa]

Hold on there Bessy ,.. I "believe" in the Easter Bunny ,..but I have yet to see the critter ..:smile:

Shake and bake wabbit ,yum yum.

 

[jflynn]

The extra cost of labor and material to use compression fittings where not needed can be cut to 25% (SWAG number) or maybe even less by the use of just a few more supports than code minimum may call for.

Properly supported and properly installed SS connectors will cost you less and will work just fine.

I dont think cost was what was being questioned here,obviously it takes more labor to install compression fittings and they do cost more..

 

[BryanMD]

I dont think cost was what was being questioned here,obviously it takes more labor to install compression fittings and they do cost more..

Well, when I mentioned the issue of proper support (way back at post #10) no one seemed to care then either.

To your point I say that EVERYTHING is about cost.
Or at least, finding that balance between effective and cost prohibitive.

 

[cschmid]

Shake and bake wabbit ,yum yum.

Oh man am I invited..I know where there is a PIG, bird, and a cow