"Hair Cutting Wire"

[kwired]

I don't think the voltage drop would be the real issue. I mean, on a 50 foot run of 12 AWG, how much voltage drop would the last inch done in 14AWG cause?

I think the real issue is the physical compromise of the connection. I don't think the math supports a few thousandths of an inch of 4 strands of stranded wire being taken out of the picture as being a voltage drop issue. Remember, the decreased diameter only exists from the cut to the point where the conductor is screwed or bolted to the connector. What's that, maybe 1/8" or less?

Voltage drop through one inch of conductor is not the issue, when conductor is increased in size because of voltage drop, sometimes you have a conductor size larger than the terminations will accept. Even if you trim off some strands to make the termination, you probably will not see any significant voltage drop across the termination. This assumes you don't trim the conductor so much that you effectively have too small of a conductor making up the termination.

Maybe I am saying the same thing you are saying.

I realize this practice is considered a "NO - NO" and does look like hackwork, and I don't make it a habit to do this myself, but I would also like to see reasons not to do it that has some scientific basis behind it. Lug not being listed is the easy way out, I want a better reason than that, like 'we tried to list it for that, but because of.....we could not get it listed.

 

[K8MHZ]

Voltage drop through one inch of conductor is not the issue, when conductor is increased in size because of voltage drop, sometimes you have a conductor size larger than the terminations will accept. Even if you trim off some strands to make the termination, you probably will not see any significant voltage drop across the termination. This assumes you don't trim the conductor so much that you effectively have too small of a conductor making up the termination.

Maybe I am saying the same thing you are saying.

I realize this practice is considered a "NO - NO" and does look like hackwork, and I don't make it a habit to do this myself, but I would also like to see reasons not to do it that has some scientific basis behind it. Lug not being listed is the easy way out, I want a better reason than that, like 'we tried to list it for that, but because of.....we could not get it listed.

Yes, we are on the same track.

There is probably more of an issue with the strands that got cut not being clamped into the terminal and thus being able to move. Or the issue of the weight of the conductor is no longer held at the termination by all the strands, putting excess stress on the strands that did not get cut.

 

[lakee911]

I think the issues with doing it are ?trimming too much,? ?supporting the wire,? and ?modifying a listed component.? When I first saw the thread, I thought to myself, ?Wow, that is some smelly wire! Mmm ? Burned hair!? :lol:

 

[G._S._Ohm]

Try it out electrically for ampacity (temp rise above ambient) and voltage drop, with only one strand remaining.
10x the resistance for 1/16th inch probably would not be noticed with Romex of a reasonable length (this is an easy calc.) but the mechanical strength would definitely be reduced.

How much mechanical strength is usually needed?

 

[kwired]

Try it out electrically for ampacity (temp rise above ambient) and voltage drop, with only one strand remaining.
10x the resistance for 1/16th inch probably would not be noticed with Romex of a reasonable length (this is an easy calc.) but the mechanical strength would definitely be reduced.

How much mechanical strength is usually needed?

Again, we are talking about the trimmed conductor being oversized for voltage drop, or other reasons where the ampacity of the full conductor is higher than what is needed for the load. If you have a 200 amp breaker with lugs that accept 250kcmil conductor max and you trimmed a few strands off a 300kcmil conductor but only enough so it will fit into the 250kcmil lug, how many problems with temp rise or mechanical strength are you going to have? That is not the same as cutting all but one strand and allowing it to operate with potentially 200 amps of load.

 

[G._S._Ohm]

My bad. The one strand would have a small fusing current even with the heat being carried away by the full cross section of the whole cable.