Terminating Class B & C Stranded Wire

Status
Not open for further replies.
augie47

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
I've been searching manufacturer sites to no avail for information on mechanical lugs and their "rating" to accept Class B & C fine stranded wire. Any links would be appreciated.
( I have a contractor terminating fine strand cables on "standard" set screw mechanical lugs.
It is my understanding that crimp lugs must be marked for fine stand cables but I am unsure about mechanical)
 
augie47 said:
I've been searching manufacturer sites to no avail for information on mechanical lugs and their "rating" to accept Class B & C fine stranded wire. Any links would be appreciated.
( I have a contractor terminating fine strand cables on "standard" set screw mechanical lugs.
It is my understanding that crimp lugs must be marked for fine stand cables but I am unsure about mechanical)
Click to expand...
Class B and C are the standard stranding, not the fine stranding.
110.14 requires that any connector or terminal used with conductors that have stranding finer than Class B and C be identified for the the specific conductor class. It applies to be compression and mechanical lugs. I am not sure I have ever seen a mechanical lug that was identified for use with finely stranded conductors.
A quick search of the Burndy catalog shows their Types QA and QDA lugs are suitable for finely stranded conductors.
 
I can't say I know what is specifically designed for the purpose, but it seems logical that if the set screw is in direct contact with the strands there is a good chance of stray strands trying to wrap around as the screw turns or even some strands just being pushed out and not being compressed in any way. But a lug with a pressure plate of some kind between the screw and the conductor seems logical that it is likely designed for fine strands, and maybe even a poor choice for a solid conductor in some cases.
 
When terminating fine stranded cables (DLO or type W) into a cam lock style connector, the manufacturer of the ddevice provides a piece of copper sheet to wrap around the fine strands before insertion into the lug. It works very well. Not sure if this would be acceptable in a application other than this.
 
Pullnwire said:
When terminating fine stranded cables (DLO or type W) into a cam lock style connector, the manufacturer of the ddevice provides a piece of copper sheet to wrap around the fine strands before insertion into the lug. It works very well. Not sure if this would be acceptable in a application other than this.
Click to expand...
Can't say I have seen a "sheet" before, but ferrule type devices are about the same thing and a common way around the problem of terminating fine strands into a lug not designed for fine strands.
 
The copper sheet wrap has been used by some UL listed panel manufacturers to terminate fine strand conductors in connectors, but without a specific instruction from the connector manufacture, I don't think it would be acceptable for a contractor to do that in a field installation.
 
Just do a search on 'Ferrules' and work backwards.

Ferrules and crimping

The most commonly used aid in the assembly of cables is the ferrule. These are standardized in DIN 46228.

Ferrules for fine strand copper conductors:

In the field of electro technology, the use of an extremely effective aid, the ferrule, is on the rise for the processing of fine strand copper conductors in different terminal points. Originally, non-insulated ferrules were used, but from 1970 onward, the insulating sleeve became common.
 
UL now allows ferrules to be used in UL508a applications.

They are not listed and some are not even recognized, so some inspectors may have issues with them for general use.
 
Status
Not open for further replies.
Top