If you connect the wrong electrical wires together, it can lead to a very dangerous electrical shock. All wires should be matched with wires of the same color. It’s very important to consult an electrician if you’re unsure about how to wire your fixture.

The standard copper wire gauge to use with any 30-amp circuit is a 10-gauge wire. The National Electric Code specifies a 10-gauge wire with appliances like water heaters running on 30 amps. If you try to use a smaller gauge wire, such as a 12 gauge, with a 30-amp breaker, you run the risk of the wire overheating and melting or causing a fire. Because of the safety hazards, the gauge of the wire is not an area to try to cut costs when connecting a 30-amp breaker to a water heater.

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.

The average cost to hire an electrician is around $350. However, every electrical job varies in scope, materials, and labor involved, so while you will likely pay anywhere between $85 and $1,100 for standard jobs, a project like rewiring a house can cost up to $30,000. You might also pay slightly higher prices if you need emergency work done or if the work involves accessing a hard-to-reach area in your home, like an attic or cramped crawlspace. You should ask your electrician for an estimate before agreeing to the work.