No, a 50A breaker would not be appropriate with #8 AWG wire for the majority of common wiring insulation types. Here's why: Ampacity

#8 AWG copper wire typically has an ampacity of 40-55 amps, depending on the insulation type (THHN, THW, etc.) and the ambient temperature. You need to look up the specific ampacity rating of the #8 wire you're using in the NEC (National Electrical Code) Table 310.16 or the wire manufacturer's documentation.

Overcurrent Protection

The breaker protects the wire from overheating and potentially causing a fire. The breaker's rating must be sized to protect the weakest point in the circuit, which is the #8 wire.

Code Violation

Using a 50A breaker with #8 wire is a code violation because you're exceeding the wire's safe ampacity.

What you need to do


Determine the actual load

How many amps does the non-continuous load actually draw? This is critical. If the load is truly less than 40 amps (or the #8 wire ampacity), a smaller breaker might be acceptable (but you'd still need to consider voltage drop).2.

Reduce the breaker size

The breaker size needs to be reduced to match or be less than the ampacity of the #8 wire. A 40A breaker might be suitable if the #8 wire is rated at 40 amps. Check the ampacity of #8 wire being used.3.

Re-evaluate the wiring

The ideal solution would be to replace the #8 wire with #6 wire for the entire run to ensure it matches the breaker. If this isn't possible, you'll need to reduce the breaker size and ensure it's appropriate for the actual load and the #8 wire's ampacity.4.

Consider Voltage Drop

With a 45-foot run, voltage drop could be a factor, especially at 50 amps. Use a voltage drop calculator to determine if the wire size is sufficient. Voltage drop is the decrease of voltage along the wire length due to its resistance.

Example

Let's say your #8 wire is THHN copper and has an ampacity of 55A ( check your wire insulation and manual for specific ampacity). The breaker would need to be 50A or less, so a 50 amp breaker would be acceptable if the actual load is 50 amps.

Important Safety Considerations



Consult a Qualified Electrician

Working with electrical wiring can be dangerous. If you're not experienced and knowledgeable, always hire a licensed electrician to do the work.

National Electrical Code (NEC)

All electrical work must comply with the NEC and local codes. The NEC is a complex document, so professional help is often needed.

Safety First

Always turn off the power at the main breaker before working on any electrical circuits.

In summary, using a 50A breaker with a section of #8 wire in the circuit is generally unsafe and violates electrical codes because the breaker will not properly protect the #8 wire from overcurrent. You need to either replace the #8 wire with #6 wire for the entire run or reduce the breaker size to match the #8 wire's ampacity and be sure the smaller breaker size can handle the load. Flag for review