temperature rating of mechanical lugs

[buck33k]

I installed some mechanical lugs in a ct can the other day. These lugs had no temp rating on them. The Ilsco catalog indicates most lugs of this (similar) type have a 90 degree rating.

What temperature rating should be used with my lugs for properly sizing the conductors? Does it need to be stamped on them?

Buck

 

[rbalex]

Re: temperature rating of mechanical lugs

These lugs are under 110.14(C)(2). They should have BOTH a "listed" ampacity AND temperature rating. The temperature rating is typically 90C and it is appropriate to use 90C rated conductors at their Table 310.16, 90C column as appropriately adjusted by ambient and Section 310.15.

Also note any restrictions that instructions for the enclosure may have.

 

[buck33k]

Re: temperature rating of mechanical lugs

Thanks for your input and information Bob.

Buck

 

[charlie]

Re: temperature rating of mechanical lugs

Also keep in mind that both ends of the run has to be rated for 90?C conductors. It is not just the connector but what the connector is connected to that matters. I don't know of any equipment where it is true that you may use 90?C conductors. Therefore, the best you can do is to use the 75?C ampacity and the 90?C ampacity may only be used for derating.

 

[john m. caloggero]

Re: temperature rating of mechanical lugs

You may have field installed mechanical lugs rated 90 degrees C, however, they are not the final determining factor, the other prerequisite is that the equipment must be rated for 90 degree terminations. The only equipment that I know of that is rated for 90 degree C terminations and conductors at the 90 degree C ampacity, is medium and high voltage equipment.

 

[bphgravity]

Re: temperature rating of mechanical lugs

What about installations where equipment and materials of different ratings are used? Can each portion of an installation be considered or should the final determination be based on the lowest value. 110.14(C) is not clear on this.

For example, say I am running a circuit from a disconnect to a panelboard. Both pieces of equipment have 75? terminations. Would it be permitted to install #1 AWG from each piece of equipment to junction boxes and then run #2 AWG between each junction box if 90? rated splices are made?

 

[charlie]

Re: temperature rating of mechanical lugs

Yes Bryan, you are indeed permitted to do that but it would not be practical. If the run is short, there would be no cost savings. If the run were long, you would be having voltage drop problems.

The underlying problem is the equipment itself and the way it is listed. Once you get away from the equipment, you may jack it up with 90?C terminations. Don't forget that all the wire in the junction box must also have a 90?C rating to do that.

 

[rbalex]

Re: temperature rating of mechanical lugs

Bryan,

Both Charlie and John's points are well taken. My original response was simply that the terminals are indeed rated 90C and would not be the basis for using a lower conductor ampacity. I did note that other restrictions may be imposed by the enclosure. (I just wish I had also noted a conductor has two ends )

Its one of the reasons I've developed this Proposal for the Forum's consideration. There is a link to an additional coordinating Proposal to clarify that each and every "condition of use" must be considered to determine a conductor's ultimate ampacity.