richwaskowitz
Senior Member
- Location
- Shelby Twp. MI, near Detroit
When 725.121 states that a Class 2 power source must be a listed class 2 power supply, does that mean that one cannot take a 20 amp (non-class 2 listed) power supply and then protect one or more 24 volt DC class 2 circuits by simply limiting each circuit to less than 100 VA by placing a 4 A breaker (4 A x 24 V = Less than 100 VA) in each circuit? Or is it saying that the power supply ITSELF must be class 2 listed?
I posit that the answer is NO, otherwise why would there be listed Class 2 power supplies if one could simply use any old 24 VDC power supply and simply stick a 4 amp breaker in the circuit. I am trying to prove this point to my customer who wants to use Class 2 wiring methods but not limit the power supply to 100VA, but rather limit the individual circuits to 100 VA with an OCPD.
I posit that the answer is NO, otherwise why would there be listed Class 2 power supplies if one could simply use any old 24 VDC power supply and simply stick a 4 amp breaker in the circuit. I am trying to prove this point to my customer who wants to use Class 2 wiring methods but not limit the power supply to 100VA, but rather limit the individual circuits to 100 VA with an OCPD.