[Explained] What Size Neutral for 200 Amp Service?

The neutral conductor is an important part of any electrical system. It provides a path for the return current to flow back to the source. When installing electrical service to 200 amps, one of the most important steps is properly sizing the neutral wire.

According to the National Electrical Code (NEC), the minimum size neutral conductor is typically 2 AWG copper or 4 AWG aluminum. This article will discuss the neutral wire sizing requirements for 200-amp service, including the applicable codes and standards.

NEC Minimum Size Requirements for 200 Amp Service Neutral

The NEC contains guidelines for selecting a properly sized neutral wire based on the electrical service amp rating. Key requirements when sizing the neutral for a 200-amp service include:

• Neutral must be sized for at least 100% of the maximum load on the service
• The minimum size is established by the amp rating of the incoming service
• A larger size may be needed for long wire runs
• Aluminum wire requires a larger size than copper due to lower conductivity

For single-family residential dwellings, the NEC allows a demand factor of 70% to be applied to the unbalanced load. This means that the neutral conductor can be sized to carry 70% of the maximum unbalanced load..

Neutral Wire Size Calculation

The size of the neutral conductor is determined by several factors, including the maximum load that the circuit will carry, the length of the circuit, and the type of conductor used.

Neutral Wire Size (AWG)=(2 × Total Amps × Length × k)(Allowable Amps × Voltage Drop %)

Where:

• Total Amps is the total current in amps (200 A for this service)
• Length is the distance from panel to endpoint in feet
• k is the constant factor for the wire gauge (NEC table value)
• Allowable Amps is the ampacity for the wire gauge from NEC
• Voltage Drop % is the maximum permissible drop (usually 3%)

Let’s take a look at an example:

• A 200-amp service with 125 ft run using 3% allowable voltage drop
• For 3 AWG copper wire, k = 21 and allowable amps = 205
• Using the formula:

Neutral Wire Size =2 × 200 × 125 × 21205 × 0.03= 2 AWG

Therefore, the minimum recommended size is 2 AWG copper wires for this 200-amp service with a 125-foot run.

Factors to Consider

In addition to the maximum unbalanced load, there are some other factors that may need to be considered when sizing the neutral conductor, including:

• Length of the circuit: Longer circuits may require a larger neutral conductor to compensate for voltage drop.
• Type of conductor used: Aluminium conductors have a lower ampacity than copper conductors. Therefore, a larger aluminum conductor may be required to carry the same amount of current as a copper conductor.
• Harmonic currents: Harmonic currents can cause the neutral conductor to carry more current than the hot conductors. Therefore, a larger neutral conductor may be required in applications where harmonic currents are present.

Recommended Neutral Wire Sizes for Different Amp Service

The following table provides a general guideline for the recommended neutral wire sizes for different amp services:

Service Rating (Amps)	Copper Conductor (AWG)	Aluminum or Copper-Clad (AWG/KCMIL)
100	4	2
150	1	2/0
200	2/0	4/0
250	4/0	300

Recommended Neutral Wire Sizes for 200 Amp Service Based on Length 

This table provides a general guideline for the recommended neutral wire size for 200-amp service based on the length of the wire. The wire sizes are listed for both copper and aluminum conductors.

200 Amp Service	Wire Size Copper (AWG)	Wire Size Aluminium (AWG)	Length of Wire (ft)
200 Amp	1/0 AWG	2/0 AWG	Up to 100
200 Amp	2/0 AWG	4/0 AWG	101-200
200 Amp	4/0 AWG	300 kcmil	201-300
200 Amp	500 kcmil	500 kcmil	301-400
200 Amp	600 kcmil	600 kcmil	401-500

Safety Considerations for Neutral Wire Sizing 

Improperly sized neutral wires can present risks of:

• Overheating leads to melted insulation and fire.
• Excessive voltage drops causing appliance damage.
• Poor electrical performance of lights, appliances, and devices.
• Nuisance tripping of circuit breakers.
• Electric shock or electrocution.

A licensed electrician can ensure your neutral wire is sized correctly per NEC standards and local codes. Never install electrical wiring without proper permits and inspections.

Professional Electrician Recommended

A licensed electrician can ensure your neutral wire is sized correctly based on NEC standards and local codes for your particular 200-amp installation. Never install unpermitted electrical work yourself.

Frequently Asked Questions (FAQs)

1. Is It Permissible to Use a Smaller Neutral Wire Than the Hot Wires in a 200 Amp Panel?

Answer: No, according to NEC guidelines the neutral should be the same size or larger than the hot wires in a 200-amp service.

2. What Is the Average Installation Cost for 200-Amp Service??

Answer: The average installation cost for a 200-amp electrical service panel can vary widely between $1,200 to $3,000 depending on factors such as location, complexity, and labor rates.

3. What Size Wire Do I Need for A 200-amp Service Wire 200 Feet Away??

Answer: Frequent tripped breakers, burnt wire insulation, outlets feeling hot, and devices not working properly can indicate undersized wires.

To conclude 

Properly sizing the neutral wire is vital when installing 200-amp electrical service. A licensed electrician can ensure your neutral conductor is properly sized for your specific application and compliant with all codes. Correct neutral wire sizing provides safety and optimal electrical performance.