Double tapped main sub panel

smorris1 · April 19, 2010, 11:57pm

Inspecting a house today and observed a double tap on the 100 AMP sub-panel from the 200 amp service panel. The wires from the service panel connected to the main lug on the 100 amp sub pane, (Screw type breakers) is this acceptable??

jhagarty · April 20, 2010, 12:04am

NO…

lkage · April 20, 2010, 12:11am

Agreed…and it looks like the branch wiring is overfused, too.

rmeier2 · April 20, 2010, 12:40am

Most likely a violation since the terminal is not rated for more than one conductor. Here’s the 2008 NEC code reference:

110.14 Electrical Connections.
Because of different characteristics of dissimilar metals, devices such as pressure terminal or pressure splicing connectors and soldering lugs shall be identified for the material of the conductor and shall be properly installed and used. Conductors of dissimilar metals shall not be intermixed in a terminal or splicing connector where physical contact occurs between dissimilar conductors (such as copper and aluminum, copper and copper-clad aluminum, or aluminum and copper-clad aluminum), unless the device is identified for the purpose and conditions of use. Materials such as solder, fluxes, inhibitors, and compounds, where employed, shall be suitable for the use and shall be of a type that will not adversely affect the conductors, installation, or equipment.
FPN: Many terminations and equipment are marked with a tightening torque.
(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.

jpope · April 20, 2010, 2:20am

Also, the EGC from the service panel is tapped into the neutral of the sub panel. This is another mess that needs correction.

In addition Sam, you need to understand the differences between the installed equipment. This statement

will lead to trouble in your reporting.

A “main” panel and a “sub” panel are two different things. It’s better to refer to them as “service” (main) panels and “sub” (other) panels.