Most people don’t know the electrical service size for their house. Nor do they know how to figure it out. As a result, electrical service size is often listed incorrectly, either because the homeowner was not sure, or the listing agent made an incorrect guess. This article serves as a short primer on the significance and assessment of the electrical service size for residential homes.
What is electrical service size?
First things first, what the heck is electrical service size anyway? Many homebuyers seem to think that whatever it is, more is better. Indirectly, the service size indicates how many electrical appliances or fixtures can run at the same time. For example, if you have an electric stove and electric clothes dryer, you will need a larger service size than if you have a gas stove and a gas clothes dryer. But you do not always need more. If your service size is adequate, upgrading the service to higher amperage only lightens your wallet.
How much do I need?
A common misconception: if you have a high-power computer or stereo system, you need a larger service size. The truth is these appliances take very little power, even though they are advertised as “high power”. On the other hand, electric stoves, electric clothes dryers or electric hot water tanks draw a lot of power. Electric heat also draws a lot of power.
Here is the typical current draw for a few major appliances:
· An electric stove with the oven and a few stovetop elements running may draw 25 or 30 amps
· An electric clothes dryer may draw 20 amps
· An electric hot water heater may draw 20 amps
· A hair dryer may draw about 12 amps
· A toaster draws approximately 10 amps
· Central air conditioning draws around 15 to 20 amps
· A hot tub may draw 20 to 40 amps
Here is a look at the service size for a few typical houses:
Description and Possible Service Size
3bdrm, 2story; Gas heat, 100 amps
3bdrm, 2story; Electric heat, 150-200 amps
5bdrm, Gas heat 150-200 amps
5000 sq-ft home, Gas heat, 200 amps