Dual wires feeding main panel

huh? Can’t recall seeing this before.

Unless those lugs are rated for 2 conductors and some are it’s wrong.

Unless those conductor are 1/0 or larger they cannot be paralled. The lug is only for one conductor, so it looks like it is wrong even if 1/0.

Was there evidence which indicated these were feeding into pawl or could one set be going out a sub?

What ever reason they have for doing it that way it is wrong. Write it up.

Those are parallel conductors and are permitted if the conditions in 310.10(H) are met. For this installation that would include that they be #1/0 or larger, of the same length, and terminated in a lug rated for two conductors.

Also since they’re in a single raceway derating factors may also be applicable.

No, sub was on a 50A breaker. Another 60A breaker went to an AC fuse box, and that one is a real mess.

On the opposite side of this exterior wall was the meter so the run is at most a few feet. No idea if the lug is rated for two.

Robert - please explain your comment about the single raceway.


Per NEC wire ampacity can be derated for either ambient temperature or by the number of conductors run through a raceway. This link explains it pretty well along with the code reference.


Parallel conductors are run so that the load can be split to allow smaller conductors to be used. This is over using on e conductor suitable for the full load and a larger conduit. Paralleled conductors can be run in more than one raceway under the conditions stated by Robert above.

Derating needs to be considered once four or more current carrying conductors are installed in a raceway due to heat issues.

If the more than 3 current carrying conductors are in a raceway 24" or less then derating would not apply. There are too many missing bits of information here to accurately elaborate any further on this particular installation.

Identification is stamped on the lug. They usually have (2) if rated for 2 conductors.

Double Lug Connections

Nice thread. I remember posting that photo. :cool:

:slight_smile: It’s helped me before.

You guys are great. Thanks for all the good info.