If you're looking to purchase an older Chicago home more than likely it had various types of electrical systems installed throughout its lifetime. As residential electrical system requirements were updated, it often took a while for homes to catch up to modern standards. One common deficiency that home inspectors look for are two-prong outlets also known as ungrounded outlets.
Since 1962, two-prong outlets, which are outlets without an attached grounding wire, have been prohibited in new construction by the National Electric Code. This was done in order to prevent electrical shock and to prevent damage to electrical equipment.
Why Are Two Prong Outlets Dangerous?
Two-prong outlets only have a hot and neutral connection. Modern three-prong outlets provide a connection to a grounding wire.
A grounding wire provides a safe path of travel if the current is unstable. Without the ground present, any unstable currents that occur can allow electricity to travel outside its intended patch (called arching) and ignite nearby material such as carpet, clothing, or furniture.
Additionally, ungrounded outlets present a risk of shock to people who are using devices in that outlet. Especially if it's in a room with running water like a bathroom or kitchen (which in this case a GFCI should be used).
Can't I Just Use a Two-Prong Adapter?
Two-prong adapters are sold at most home improvement stores and are very inexpensive (around $1). If you lived in an older home with two-prong outlets these were probably very familiar to you. However, they are still a poor alternative to a modern grounded receptacle. The main reason is that most people don't probably install them. The "ring tab" on the adapter needs to be secured via the screw that holds the ground screw. Even if installed properly, there is still a possibility that the box that holds the outlet isn't grounded.
Is It as Simple as Swapping the Two-Prong Outlet with a Three-Prong?
Not quite. You can swap out outlets properly if there is an existing ground wire running from the main electrical panel to that specific outlet. However, in our experience most people don't do this. They simply remove the two-prong outlet and install a modern three-prong outlet. While this "works" because there's still electrical current and modern devices can be inserted into the outlet, it is still very unsafe as it still remains ungrounded. As home inspectors, our electrical testers that we use for every inspection tells us if an outlet is ungrounded. We usually see this in an older home and is usually a sign of electrical work being performed by a person who isn't a professional electrician. While the outlet "looks the part," it's no safer than an improperly installed adapter. It's still poses a safety risk.
Are Two-Prong or Ungrounded Outlets a Dealbreaker?
Absolutely not! Every major system (your furnace, air conditioner, etc.) in a home has a finite life including the electrical system. Chicago boasts a large number of older homes. In fact, if the house is in the city limits there's a high chance that it was built prior to 1962 when the code that three-prong outlets were required.
Every time we encounter an ungrounded outlet in a home inspection, we recommend that the house be further evaluated by a professional electrician. More than likely, two-prong or ungrounded outlets are just one indicator of an outdated electrical system. For example, it's not uncommon to see cloth wiring, outdated electrical panels, and 100-amp service in these older homes. An electrician (especially a Chicago-based one) is well versed in updating these older homes to modern standards.