Yes, you're right to question this. Here's a breakdown of the issues and why it's a problem

Understanding the Problem: Overcurrent Protection and Conductor Size

The fundamental principle is this: The overcurrent protection device (in this case, the 20A breaker feeding the disconnect) is there to protect the weakest link in the circuit. The weakest link is the 14 AWG wire. 14 AWG Ampacity

14 AWG copper wire is typically rated for a maximum of 15 amps according to the NEC (National Electrical Code).

20A Overcurrent Protection

A 20A breaker permits up to 20 amps to flow.

The Mismatch

The 20A breaker will not trip until 20 amps or more flows through the circuit. The 14 AWG wire, however, could overheat and potentially cause a fire before the breaker trips because it is rated for a maximum of 15 amps.

Answer to Your Question


"Doesn't this essentially make the 14g overused?" YES. The 14 AWG wire is at risk of being overloaded because the 20A breaker allows more current than the wire is safely rated to carry.

Why Connecting 12 AWG and 14 AWG is (Generally) Problematic

While it's possible to connect 12 AWG and 14 AWG wires, it's only acceptable if the overcurrent protection device is sized appropriately for the smallest wire in the circuit.

Acceptable Scenarios (Rare in this case, but for completeness)



Taps

The NEC does allow for "tap conductors" under very specific conditions (NEC 240.21). This is where a smaller conductor is used for a short run to a specific load. However, there are strict requirements for the length of the tap, the overcurrent protection, and the ampacity of the tap conductor. Given your description, this likely doesn't apply in this situation. Taps are typically used in industrial environments.*

Specific Equipment

Some equipment may be listed and labeled to allow for specific conductor sizes.

Why This is a CSLB Concern

This situation is a clear violation of electrical safety standards. It creates a fire hazard and potentially puts the homeowner at risk. Proper electrical work requires that the overcurrent protection be sized to protect the smallest conductor in the circuit.

Corrective Action

The following corrections should be made:1.

Downsize the Breaker

The best solution is to replace the 20A breaker with a 15A breaker. This will provide proper overcurrent protection for the 14 AWG wiring.2.

Rewire with 12 AWG

Another option would be to completely rewire the circuit with 12 AWG conductors. This is more involved but would allow you to keep the 20A breaker.

In summary, the 20A breaker feeding 14 AWG wiring is a safety hazard and a code violation. The breaker must be changed to 15A, or the wiring must be upgraded to 12 AWG. Flag for review