Wiring a 240V 27kW 3-Phase Heater in a 200 Amp Service Panel: A Comprehensive Guide

Wiring a 240V 27kW 3-phase heater in a 200 amp service panel may seem challenging, especially considering the unique requirements and the absence of 3-phase systems in pre-covid times. This guide offers a detailed step-by-step process to ensure safe and efficient installation, including calculations and necessary precautions.

1. Understanding the Load Calculation

A 27 kW heater at 240V in a 3-phase system will draw a considerable amount of current. To determine the current, you can use the following formula:

I P / (√3 × V)

Where:

P Power (27,000 watts) V Voltage (240 volts)

Calculation:

I 27,000 / (√3 × 240) ≈ 65.0 A

2. Check Service Panel Capacity

Ensure that your 200 amp service panel can handle the additional load. Consider the total load on the panel, including the 27 kW heater and other circuits to avoid overloading the system.

3. Choose Appropriate Circuit Breaker

For a 27 kW heater drawing approximately 65A, you typically need a 70A or larger circuit breaker. Ensure that the breaker is rated for 3-phase loads.

4. Select the Correct Wire Size

The wire size is crucial for handling the current without overheating. For 65A:

Copper Wire: 4 AWG Aluminum Wire: 2 AWG

Refer to local electrical codes for specific requirements, as they can vary.

5. Install the Circuit Breaker

Turn off the main power to the service panel. Install the 70A circuit breaker in an available slot in the panel.

6. Run the Conduit and Wiring

Run conduit from the service panel to the heater location. Pull the appropriate gauge wire (4 AWG copper or 2 AWG aluminum) through the conduit. Include three hot wires L1, L2, L3 and one ground wire.

7. Connect the Wiring

At the service panel: Connect L1, L2, and L3 to the circuit breaker. Connect the ground wire to the ground bus. At the heater: Connect the three hot wires to the corresponding terminals on the heater. Connect the ground wire to the heater's ground terminal.

8. Test the Installation

Double-check all connections to ensure they are secure.

Turn on the main power and then the circuit breaker. Use a multimeter to verify that the voltage is correct at the heater.

9. Follow Local Codes and Regulations

Always adhere to local electrical codes and regulations. Consulting or hiring a licensed electrician is recommended to ensure safety and compliance.

Safety Precautions

Always turn off power before working on electrical systems. Use appropriate personal protective equipment (PPE). If unsure about any step, consult a professional electrician.

This high-level overview provides a basic framework for wiring a 240V 27kW 3-phase heater in a 200 amp service panel. Actual installation may involve additional considerations based on local codes and specific equipment requirements.

Keywords: 3-phase wiring, 200 amp service panel, heater installation