Cable size vs Lug size

[Hassan Asran]

Hey,
we facing a problem in one of our project that needs your advice, the problem is that the low voltage 380V/220V switchgears from EATON being ordered to our project are coming Circuit breakers with terminal Mechanical lugs size 750KCMIL from Ilsco part # D3591 and Compression lugs size 750KCMIL from HEX part # HSBL-750L2 while the size of the cable we shall terminate to it is 768KCMIL, Please advice is it correct or not to use this lugs ? and we thought to use cable reducers but i couldnot find a reducer from 768KCMIL to 750KCMIL as it is very small difference, can any body can support me with a code or a response which i can use to convince my client that this lugs are still correct to terminate this cable to it and no need to change it to bigger size .... please advice.
thank you.

 

[Dennis Alwon]

I agree that it is a small difference but I am not sure the conductor will fit. If it does it would be a violation but I suspect it would work fine.

There should be a lower end that the lug will also accept. Often you see, for example, 250-750 kcm,, Are there reducer that will go to the lower limit?

 

[Hassan Asran]

Cable size vs Lug size

I agree that it is a small difference but I am not sure the conductor will fit. If it does it would be a violation but I suspect it would work fine.

There should be a lower end that the lug will also accept. Often you see, for example, 250-750 kcm,, Are there reducer that will go to the lower limit?

Actually I inserted the conductor 768Kcmil easly with my bare hand inside lug barrel without any phisical effort on it and didnot cut any strands even and i could turn around the lug while the cable inside it which means that is is not tight on it, so can you clarify why it is a violation as you said above? i checked NEC code and couldnot find any phrase violate to use bigger size cable with smaller lug even Mike Holt in one of his answers to this issue give the option "Order a terminal device that crimps on the end of the conductor and terminates on the terminal" you can find that at below link http://ecmweb.com/code-basics/splices-and-terminations-conductors but still i believe that could be used if the cable was oversize for the voltage drop or its size with much bigger than the lug and cannot fit without cut strands but my case is different ...... what you think Dennis?

 

[Dennis Alwon]

The violation would be in 110.3(B). So if it is marked for 750 then technically your conductor would be a violation. I bet if the manufacturers were working with metric sizes your conductor would probably be Okay. I would check with the authority there and see what they think

(B) Installation and Use. Listed or labeled equipment
shall be installed and used in accordance with any instructions
included in the listing or labeling.

 

[don_resqcapt19]

Actually I inserted the conductor 768Kcmil easly with my bare hand inside lug barrel without any phisical effort on it and didnot cut any strands even and i could turn around the lug while the cable inside it which means that is is not tight on it, so can you clarify why it is a violation as you said above? i checked NEC code and couldnot find any phrase violate to use bigger size cable with smaller lug even Mike Holt in one of his answers to this issue give the option "Order a terminal device that crimps on the end of the conductor and terminates on the terminal" you can find that at below link http://ecmweb.com/code-basics/splices-and-terminations-conductors but still i believe that could be used if the cable was oversize for the voltage drop or its size with much bigger than the lug and cannot fit without cut strands but my case is different ...... what you think Dennis?

Is the 768kcmil a finely stranded conductor? If so, in addition to the size issue, you also need a connector that is rated for use with finely stranded conductors. I don't see that as a big deal if the connector is a compression type connector, but it is a big deal if it is of the set screw type.

I expect that it is of the set screw type as I have never been able to fit the finely stranded DLO type cables into the next smaller sized compression lug. For example 535.3 kcmil DLO does not fit in a 500kcmil compression connector.