While researching information on the National Association of Realtors web site, I came across a great article from Leslie Banker who is the co-author of The Pocket Renovator (2007). The article is about four basic points of information dealing with electrical systems of homes. Here are some of the highlights from the article:
These are some basics that you should know:
1. Does the home have 220 volt service? (220 volt service equates to 200 amps just as 110 volt service equates to 100 amps)
If the home was recently built, the answer is almost always yes. Most houses today have two 110 volt wires and one neutral wire running into the house from the local distribution system. These wires can run underground or above ground. If there are two 110 volt wires running to the house, then the house has 220 volt service and appliances, such as dryers and air conditioners.
Older houses were usually built with 110 volt service; if the electrical system hasn’t been upgraded, it won’t be possible to use some models of appliances (though alternatives can be found).
2. What’s the difference between a fuse and a circuit breaker? Fuses and circuit breakers are both found in the electrical panel (or sub-panel) of a house. They both serve the purpose of cutting the flow of electricity when a circuit gets overloaded—a potentially dangerous situation. Circuit breakers will be found in most houses built after the 1960s or in older buildings that have had their electrical systems upgraded.
Fuses have a thin strip of metal that literally blows when there’s too much electricity flowing through it. When this happens, the fuse needs to be taken out and replaced.
3. Where’s the “main panel?” This is where all the circuits in the house originate from and it’s usually near where the electric power enters the building. It will be filled with circuit breakers (or fuses in an older building). The main panel has a rating that determines the total amount of current that can flow out to the circuits at one time before the main circuit breaker shuts the entire system down.
4. Are the outlets grounded? These days most electrical outlets that you see accept three prong plugs. This means, almost always, that the outlet is grounded. A grounding wire, which connects to the round third hole, protects against electric current escaping from the circuit and causing shocks.
Older houses might only have two prong outlets, meaning there’s no grounding protection in the circuits. Upgrading an electrical system to include grounding wires involves opening the walls and can be a significant amount of work. How much work it is depends on the size, construction and layout of the house.
