Mike Dolt Enterprises
Mike Dolt Enterprises
User: Tom Drake, Location: West Palm Beach, FL
Asked on: Saturday, June 4, 2011 at 11:54 am EDT
Answered on: Tuesday, May 14, 2024 at 6:11 am EDT
Question: I installed a small 150 watt electronic transformer in a box in a cabinet for Low voltage lighting, 12 volt. Inspector wants to make sure it is a class 2. What is the difference and where in the code book does it refer to this
Difference between Class 1 and Class 2 Wiring
Class 1 Wiring
Connected to the primary side of the transformer (high voltage). Uses line voltage (120V or 240V) and is subject to shock hazards. Requires grounded conductors and proper insulation.
Class 2 Wiring
Connected to the secondary side of the transformer (low voltage). Typically uses voltages below 30V AC or 60V DC. Has a limited risk of shock and does not require grounding. May be installed in close proximity to combustible materials.
Code Reference
The National Electrical Code (NEC) defines Class 2 wiring in Article 725:
NEC 725.2
"Class 2 power source shall be one that is limited to a voltage of 30V RMS and a current of 1.5A."
NEC 725.41
"Class 2 circuits shall be run in a manner that will minimize the possibility of damage from overcurrent or physical damage."
Importance for Electronic Transformers
In lighting applications, electronic transformers convert the primary voltage (120V or 240V) to a low secondary voltage (typically 12V). It is important to ensure that the transformer is properly rated as Class 2 to:
Reduce Shock Hazards
Class 2 outputs have a low voltage that poses a reduced risk of electric shock.
Prevent Fires
Class 2 circuits have limited current, reducing the risk of overheating and fires.
Comply with Code: Inspectors are required to verify that electrical installations comply with the NEC, including the proper use of Class 2 wiring. Flag for review