Controls & Disconnecting Means — Texas Journeyman Practice Questions

2 questions · 2% of the NEC Knowledge exam

Worked questions

1. Does pressing a control-system STOP pushbutton normally establish an electrically safe work condition?

AYes; every STOP button is a disconnect
BYes; if the pilot light goes dark
No; isolate, lock out, and verify de-energization
DNo; because equipment can never be de-energized

Why C is correct

A control command can fail or leave line-side and stored energy present. Safe electrical work requires identifying and isolating sources and verifying the condition; a pushbutton or indicator is not normally an isolating means.

2. A control transformer is added inside a motor control panel. What must be coordinated?

AOnly the motor nameplate color
BOnly the enclosure door latch
Primary and secondary protection under the applicable transformer rules
DThe building plumbing vent size

Why C is correct

Control transformer conductors and overcurrent protection must be coordinated with transformer size, primary protection, secondary conditions, and any listed industrial control panel requirements.

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Controls & Disconnecting Means — Texas Journeyman Practice Questions

Worked questions

1. Does pressing a control-system STOP pushbutton normally establish an electrically safe work condition?

2. A control transformer is added inside a motor control panel. What must be coordinated?

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