110.14 Fine Stranded Connectors

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tom baker

tom baker

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2011 NEC 110.14 add the requirement for fine stranded conductors to use connectors and terminals identified for the specific conductor class.
Has anyone seen an issue with fine stranded conductors being damaged from using an the incorrect connector/lug?

I have a compression terminal kit from Burndy, it has lugs for fine stranded conductors and the barrel opening is slightly larger than for a class B or C stranding conductor.

Perhaps the damage would come from a set screw lug?
 
I have not seen issues with compression termination used with fine strand conductors, even where the termination was not listed for use with fine strand conductors. I think the issues are mostly with mechanical connections.
 
tom baker said:
I have a compression terminal kit from Burndy, it has lugs for fine stranded conductors and the barrel opening is slightly larger than for a class B or C stranding conductor.

Perhaps the damage would come from a set screw lug?
Click to expand...

I think the slightly larger opening makes it less likely that the fine strands will be "peeled back" by insertion into the compression lug, since they're less stiff.

When I use fine stranded conductors (type W, or "welding" wire) in control panels, I always use wire crimped wire ferrules. It keeps the strands tidy, and more importantly, keeps setscrews from damaging the conductor's strands. With a few exceptions, I always use ferrules when I build control panels, no matter the stranding type. I've even occasionally cused them in breaker panels to protect regular THHN conductors from the awful terminals on some "Homeline" style circuit breakers; the screws tear up the strands too much for my taste.



SceneryDriver
 
I have seen on a large portable generator (not required to be listed) where the fine stranded bonding jumpers were wrapped with a thin copper sheet and then inserted into the large lug, this was 3 or 4 wires in one lug.
 
tom baker said:
I have seen on a large portable generator (not required to be listed) where the fine stranded bonding jumpers were wrapped with a thin copper sheet and then inserted into the large lug, this was 3 or 4 wires in one lug.
Click to expand...

It would to know how the manufacturer stands behind that. I would highly doubt if they varified connection method with those that UL486 requires to include a pull and temperature rise tests. This is why it is best to go with a manufacture who manufactures listed products.
 
tom baker said:
2011 NEC 110.14 add the requirement for fine stranded conductors to use connectors and terminals identified for the specific conductor class.
Has anyone seen an issue with fine stranded conductors being damaged from using an the incorrect connector/lug?

I have a compression terminal kit from Burndy, it has lugs for fine stranded conductors and the barrel opening is slightly larger than for a class B or C stranding conductor.

Perhaps the damage would come from a set screw lug?
Click to expand...

NEMA states this:

When fine-stranded cables are improperly used with set-screw type mechanical connectors, there is an increased risk of overheating and/or wire pullout. Strands may break or be forced between the connector screw and threads. A false torque reading could result, which increases the risk of overheating and wire pullout. Even if the strands do not break and the wires are not forced into the threads, the initial torque setting may not hold in a typical connector. Even if the connection is re-tightened later, the connection may continue to loosen and create a high resistance connection.
 
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