How to Safely Replace Old Knob and Tube Wiring in Your Home

Introduction

Replacing old knob and tube wiring in your home can seem like a daunting task, but it is doable if you take the proper safety precautions. Knob and tube wiring was commonly installed in homes built before the 1940s and can pose safety hazards like overloaded circuits and fire risks. In this article, I will walk you through the complete process of how to safely update your outdated electrical system.

Dangers of Knob and Tube Wiring

Knob and tube wiring consists of single black rubber-insulated wires run through ceramic knobs and tubes. It has no ground wire and often not enough amperage for modern household needs. Here are some of the main dangers:

• Fire hazard - The old, brittle insulation can crack and expose bare wires, leading to shorts and sparks. This can ignite combustible materials in walls and ceilings.

• Shocks and electrocution - Damaged areas of insulation can energize metal components like appliance chassis, putting you at risk for shocks.

• Lack of grounding - Without a ground wire, you lose an important safety feature that prevents shocks and allows overcurrent devices to work properly.

• Insufficient electrical capacity - Knob and tube circuits are often only 15 or 20 amps, which is inadequate for today's high-wattage appliances.

The bottom line: knob and tube wiring cannot safely support the electrical demands of modern life. Replacement should be a top priority.

Planning Your Wiring Replacement Project

Before beginning work, take time to carefully plan the project. Rushing in without proper planning can not only produce poor results but also create new hazards.

Evaluate scope of work

• Inspect - Locate all knob and tube wiring and examine condition. Look for cracked insulation and splices.

• Consider needs - Determine what improvements are required based on your home's electrical demands.

• Prioritize - Start with high priority areas like kitchens and consider budget when deciding on scope and timeline.

Hire a qualified electrician

• Although a DIY project is possible, it requires advanced skills. An experienced electrician is recommended.

• Confirm they are licensed and insured. Ask for references from past jobs.

• Clearly explain the project scope and safety concerns.

Obtain required permits

• Permits are required for most wiring projects. Research permit needs based on local jurisdiction.

• Permits help ensure work meets electrical code. It adds an important layer of safety oversight.

Safety planning

• Turn off power at the main breaker before starting work. Verify power is off with a voltage tester.

• Have a fire extinguisher and other safety equipment on hand.

• Prevent access by children and pets to the work area.

How to Replace Knob and Tube Wiring

Once planning is complete, you are ready to safely remove the old wiring and install new. Proceed in steps:

1. Turn off power and disconnect knob and tube circuits

• Shut off the main breaker and all individual branch circuits.

• Verify power is off with a non-contact voltage tester. Test wires inside boxes as well as at outlets.

• Remove all fuses or breakers and outlet covers associated with knob and tube circuits.

2. Remove knob and tube wiring

• Start by taking wiring out of boxes carefully to avoid damage.

• Cut into walls/ceilings to access full wiring runs. Remove insulation to fully expose.

• Disconnect wires from any splices and remove from knobs and tubes.

3. Install new wiring system

• Run new NM electrical cable through walls and ceilings. Follow code for proper wire gauges.

• Make connections using wire nuts and secure cables to framing members per code.

• Terminate wires properly at main panel, outlets, switches and junction boxes.

4. Replace/install devices and covers

• Install compatible new outlets, switches, light fixtures. Use new work boxes where needed.

• Attach cover plates and verify grounding by outlet tester.

• Label new circuits clearly at the panel. Update household records accordingly.

5. Inspect and test completed system

• Visually inspect to ensure cables are secured and there is no damage.

• Test all outlets and fixtures to verify proper function and no open grounds.

• Check for hot spots at wires, devices and junction points using an infrared camera or probe.

• Schedule inspection by the local building department to obtain final approval.

Work Safely! Key Tips to Remember

• Turn off power at the main breaker before starting and verify it is off.

• Only work on wiring when it is confirmed de-energized for safety.

• Keep a fire extinguisher, first aid kit, and voltage tester nearby.

• Wear personal protective equipment like glasses and work gloves.

• Never leave live wires exposed - cap and tape any inactive wires.

• Dispose of old insulation and wiring properly per environmental regulations.

• Always get the required permits and inspections for code compliance.

Replacing knob and tube wiring requires care and attention to detail, but modernizing the electrical system in my home was very worthwhile. The sense of security and safety is priceless, not to mention finally having adequate capacity for all my home's circuits. If planned carefully and executed safely, you can successfully tackle this project too!