Have An Electrician Check Your 1950s Home's Breaker Panel When Installing A New AC Unit

When our family quickly began outgrowing our home, my husband and I couldn't decide whether to add onto our current home or move into a larger one. One day, when we were checking the local area looking for "home for sale" signs, we saw a sign we couldn't take our eyes off -- there was a large plot of land for sale for a great price in a great location. We had never thought of building our own home before, but after a little research, we realized that it wasn't as costly as we thought, especially considering the great deal we got on the land. The entire process was a learning experience, but thankfully, the building team was very pleasant and helpful. We now love our new home, and I am excited to share our experience on our new blog. I also plan to post many planning and construction tips!

Have An Electrician Check Your 1950s Home's Breaker Panel When Installing A New AC Unit

28 March 2016
 Categories: Construction & Contractors, Articles


In the 1950s, air conditioning wasn't as common as it is today, even though modern AC was invented all the way back in 1902 by Willis Carrier. As late as 1965, only 10 percent of homes in the United States had air conditioning. If you own a home that was built in the 50s and don't have an AC or heating unit, you may be tempted to install an air conditioner this summer. But, before you do, you should call an electrician to check your home's breaker panel.

Different Electrical Needs

It's important to remember that the breaker panels installed in modern homes are able to handle heavier loads than those put in houses in the 1950s. With all of the fancy cooking gadgets used now, today's kitchens may use just as much electricity as an entire house did back in the 50s or 60s. Thus, today's breaker panels need to have higher capacities than they used to.

Homes today often are equipped with 200-amp breaker panels, which have more than three times the capacity of the 60-amp panels that were frequently used in the 1950s.

An Air Conditioner's Electrical Needs

Unless your home's electrical panel has been upgraded to a 200-amp model, running a 200-volt line for an air conditioner to it may not be safe.

Air conditioners need a lot of power when they're starting up. Appliances tend to draw an more electricity when first turning on, but use less as they run. The amps required when starting up are called locked rotor amps, abbreviated LRA. The following list shows the number of amps that different sized air conditioners draw when turning on:

  • 1-ton AC units need 33 LRAs
  • 2-ton AC units need 67 LRAs
  • 3-ton AC units need 100 LRAs
  • 4-ton AC units need 117 LRAs
  • 5-ton AC units need 145 LRAs

Smaller electrical panels often don't provide enough amps for an air conditioner to start up. For instance, just a 1-ton AC unit needs over half of a 60-amp breaker panel's maximum, and a 2-ton model's draw of 67 LRAs exceeds a 60-amp panel's maximum.

When the demand for amps exceeds a breaker's maximum, the circuit becomes overloaded. This causes an inconsistent flow of electricity, as it's divided unevenly among all the appliances and lights requiring it. The varying flow will cause lights to dim, and it could make your air conditioner's motor burn out.

Your Electrical Needs

No matter where you live in the country, you will likely want to install an air conditioner that's larger than 1 ton. 1-ton air conditioners are only effective for small homes in the far Northern United States. If your house has more than 1,100 square feet or is in the Northern U.S., you'll likely want a 2- or 3-ton unit. You may even want to opt for a larger one.

Thus, your breaker panel will need to deliver 67 or 100 LRAs, even when other electrical appliances are on. You'll likely need a 200-amp breaker panel. If you get a larger air conditioner, you might even need a separate panel installed specifically for the air conditioner.

Your Home's Breaker Panel

To make sure your home's breaker panel will be able to deliver this amount of power, call an electrician who can check your home's electrical system. They'll be able to look at the panel that's currently installed and the load placed on it by other electrical appliances. If necessary, they'll also be able to upgrade your panel so that it can provide your new air conditioner with the power it needs and run a new 220-volt line for the unit.