Subpanel wiring - disconnect near subpanel

Electrical · Distribution Panels · printed page 97 (PDF page 98)

Book index entries

Subpanel – Wiring Disconnect by Subpanel Distribution Panels – Electrical Electric Distribution Panels Electric Subpanel Wiring Subpanel – Wiring Electrical

Text in the illustration

subpanel
40-amp breaker
off
on
this is not good practice - although the 40-amp breaker protects the feed wire from overloading, a short circuit (as shown) could be enough to overheat the feed wire without either the 40-amp breaker or the main breaker “noticing”
to ground
main breaker
service conductors
8 gauge copper feed wire connected directly to main panel bus bars
nail driven into wire causes short circuit
neutral bus bar
bus bars
grounding terminal

Generated explanation

The illustration shows a main distribution panel feeding a subpanel through an 8 gauge copper feed wire connected directly to the main panel bus bars. A separate 40-amp breaker is located beside the subpanel, at the receiving end of the feeder. A nail driven into the feeder between the panels is shown causing a short circuit. The annotation identifies this as poor practice: the 40-amp breaker protects against overloading but may not protect the upstream feeder from the illustrated short circuit, and the main breaker may not respond before the feeder overheats. The main panel also shows service conductors, a main breaker, branch breakers, a neutral bus bar, and a grounding terminal.

Related illustrations

0573

Subpanel wiring - disconnect near main panel

· p. 97

The illustration shows a main electrical panel supplying a subpanel through a separate 40-amp breaker located near the main panel. An 8 gauge copper feeder connects directly to the main panel bus bars and passes through