How to Calculate Feeding a Bedroom Addition From an Older Electrical Panel

Introduction

Adding a bedroom onto your home can be an exciting project that allows you to gain more living space. However, it also presents some electrical challenges, especially if your existing electrical panel and wiring are older. Calculating the electrical load for the addition and determining if your current system can handle it is crucial before you begin construction. This article will walk you through the key factors to consider when feeding a new bedroom addition from an older electrical panel.

Assess Your Existing Electrical Panel

The first step is to examine your current electrical panel (also known as the breaker box) and take notes on the following:

• Age of the panel - Older panels used fuses instead of circuit breakers. Upgrading to a modern circuit breaker panel may be required.

• Amperage rating - This indicates the maximum power your panel can deliver. For a 200 amp panel, you have 200 amps to distribute among all your home's circuits.

• Open breaker slots - This shows available space to add a new circuit for the addition. If no open slots exist, your panel may need to be replaced with a larger one.

• Wiring gauge - Old wiring is usually copper rather than modern aluminum and may not handle added electrical load.

Calculate Electrical Load for the Bedroom Addition

The next step is calculating the estimated electric load for your new bedroom. Consider the following factors:

Lighting and Outlets

• Count the number of outlets, switches, and light fixtures planned. Multiply by 100 watts per outlet and 150 watts per light.

• Example: 1 bedroom with 10 outlets and 4 lights = 1,000 watts + 600 watts = 1,600 watts

Major Appliances

• Estimate wattage of any major appliances. Example: 5,000 watts for air conditioner

General Load

• Add 1,500 watts for general load per room. This covers small appliances, electronics, etc.

• Total the wattage for lighting, appliances, and general load.

• Example: 1,600 watts lights + 5,000 watts A/C + 1,500 watts general = 8,100 watts total load.

Compare Load to Panel Capacity

• Compare the total calculated load to your panel's amperage rating.

• To convert watts to amps, divide by 120 volts.

• Example: 8,100 watts / 120 volts = 67.5 amps

• If the total load exceeds 70-80% of your main panel rating, an upgrade is likely needed.

Options for Upgrading Electrical Service

Here are some options if your existing panel can't handle the added bedroom load:

• Install a subpanel - This smaller panel connects to and draws power from your main panel.

• Replace the main panel - Install a new panel with a higher amperage rating and more breaker space.

• Install a new meter/panel - For large additions, running a new electrical service line and meter may be required.

• Add a generator - A standby generator can provide backup power if your overall load is borderline.

Conclusion

Adding a bedroom addition involves carefully calculating the electrical load and assessing if your older panel can handle it. Upgrading wiring, breakers, or the entire panel may be needed to power the addition safely. Planning ahead and consulting an electrician is key.

Key Takeaways

• Examine the age, amp rating, breaker space, and wiring of your existing electrical panel.

• Estimate lighting, appliance loads, and general power needs for the addition.

• Compare total load to your panel's capacity to see if an upgrade is needed.

• Options include a subpanel, new main panel, new electrical service, or generator.

• Consult an electrician to ensure your system can handle the additional load.