This depends on how many outlets you have and the current status of your electrical system. The cost to ground an outlet clocks in at $75 to $480 per outlet, so multiply that by the number of outlets in your home to arrive at a rough estimate. However, this is for simple projects with no obvious issues with the system. Your final bill could vary widely from your calculations.

It can be safe to buy or live in a house with knob and tube (K&T) wiring, but only if the system is in good condition, functional, and has been thoroughly inspected and approved by a licensed electrician. Never purchase a home with K&T wiring without getting a professional electrical inspection first.

Key considerations include:

• Safety and Condition: An inspector will verify that the wiring is safe and has not deteriorated. Over time, the insulation can wear away, leaving exposed wires that pose a significant fire or shock hazard.

• System Capacity: The electrical service should be at least 60 amps. However, even at this capacity, K&T systems often struggle to handle the demands of modern appliances and electronics.

• Lack of Grounding: Knob and tube wiring is an ungrounded system, which is a safety concern for many modern devices.

• Ongoing Maintenance: If you live in a home with K&T wiring, it's recommended to have it inspected by an electrician every one to two years to ensure it remains in safe working order.

Ultimately, any inspection or modification of a knob and tube system should always be performed by a certified professional.

A 3-prong, 15-amp, 120-volt outlet is standard in the U.S. These have two vertical slots and a U-shaped grounding hole, which suits most home electronics, from televisions to microwaves. Three-pronged outlets are safer than 2-pronged ones, as the third wire, known as the grounding wire, helps prevent shocks and electrical fires.

Often, you can add extra breakers to an electrical panel. A new breaker can help with new appliance needs, and it’s a common solution when finishing an attic or basement. However, adding extra breakers can’t bring in more amps to your house, so you still need enough amp service to power everything in total.