Where in the NEC ???

[Scorpio]

If you have 400 amp single phase disconnect with parallel runs 3.0 copper - can you put more than 1 wire under a lug - does disconnect have to have more than 1 lug to accommodate the parallel runs, does the panel? I believe there is an article in the NEC that says this is not correct but I can't find it or remember the exact details. Anyone know?

 

[zbang]

You can put more than one wire in a single lug if the instructions for the lug (or disconnect if it was provided with lugs from the factory) say so:
110.3 Examination, Identification, Installation, and Use of Equipment.
(B) Installation and Use. Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.

If the lug instructions say "one wire" then that's what you get.

 

[jumper]

The terminals/lugs would need to identified/marked for more than 1 conductor/wire.

110.14(A) Terminals. Connection of conductors to terminal parts
shall ensure a thoroughly good connection without damaging
the conductors and shall be made by means of pressure connectors
(including set-screw type), solder lugs, or splices to
flexible leads. Connection by means of wire-binding screws or
studs and nuts that have upturned lugs or the equivalent shall
be permitted for 10 AWG or smaller conductors.
Terminals for more than one conductor and terminals
used to connect aluminum shall be so identified.

 

[kwired]

Most 400 amp devices you will find that have factory installed lugs are usually a type that will accept multiple conductors, but you may want to double check and not just assume they are.

 

[MasterTheNEC]

Being that you simply stated it was a 400 Disconnect and made reference to parallel conductors. I would just say be sure that what you are actually running actually are "parallel" conductors in accordance with the NEC. Check our 310.10(H) and just make sure you are doing apples to apples and not oranges to apples. (crappy analogy but hey..I went with it)