How to Safely Replace Old Copper Wiring in Your Home

Replacing old copper wiring in your home can seem like a daunting task, but with proper planning and safety precautions, it can be done safely by a homeowner. Here is a step-by-step guide on how to tackle this project.

Assess the Existing Wiring

The first step is to thoroughly assess the existing electrical wiring in your home.

• Examine the copper wiring to see if it is cloth-insulated or plastic-insulated. Cloth wiring is very old and prone to deterioration. Plastic-insulated wiring may be salvageable if it is in good condition.
• Look for signs of wear and tear like cracked or frayed insulation. This can indicate a dangerous short circuit hazard.
• Note down any outlets that spark when plugging in appliances or have very little wire exposed at the terminals. This usually means undersized wiring.
• Check for knob and tube wiring. This very old wiring system is obsolete and must be completely replaced.
• Consider hiring an electrician to do a professional assessment if you are unsure about the extent of the wiring upgrades needed.

Thoroughly scoping out the electrical system will help determine if a full rewire is necessary or if only certain sections need replacement.

Develop a Wiring Plan

Once the inspection is complete, you can start planning the details of the rewiring project.

• Draw up a wiring diagram marking all the lighting fixtures, switches, outlets and appliances in each room. Note the locations where wiring replacement is needed.
• Decide on the wire size needed for each circuit - usually 12 AWG for 15 amp circuits and 10 AWG for 20 amp circuits.
• Choose the type of wiring - either NM (non-metallic) cable or flexible armored cable (BX). NM is easier for DIY installation.
• Mark the paths for running the new wiring between the electrical panel, outlets and fixtures. Avoid exterior walls where possible.
• Determine if you want to add any new wiring features like dimmers, motion sensors or smart switches. Plan these locations in advance.
• Shop for all the necessary electrical supplies like wire, boxes, receptacles, breakers, tools etc.

Safety Gear and Precautions

Working with electrical wiring requires maximum safety at all stages.

• Wear safety goggles and work gloves when handling wires.
• Use a multimeter to de-energize wires before working on them. Turn off the main breaker too.
• Have a fire extinguisher on hand.
• Work slowly and be cautious of live wires hidden behind walls.
• Keep a first aid kit ready for minor injuries.
• Exercise caution on ladders and when working in tight spaces.

It is also highly recommended to install arc fault circuit interrupters (AFCIs) with the new wiring. These advanced safety devices shut off electricity when a dangerous arc occurs that could start an electrical fire.

Removing Old Wiring

Once the prep work is done, you can start removing the old copper wiring:

• Turn off power at the main breaker panel before disconnecting existing wires. Double check with a multimeter.
• Remove existing outlets, switches and light fixtures from the walls. Take pictures if necessary to help with reassembly.
• Carefully pull out the old wires from the boxes - this is where hidden wires become a hazard if energized.
• Salvage any undamaged plastic-insulated wires if possible. Old cloth-insulated wires should always be discarded.
• Use a voltage tester to confirm wires are completely dead before pulling them out of the walls.
• Coil up and safely dispose copper wires too damaged to reuse. They cannot just be thrown in the trash.
• Remove abandoned junction boxes and conduit no longer needed. Seal up openings in walls to draft-proof.

Take precautions against lead paint and asbestos insulation if your home wiring dates back to the 1960s or earlier.

Running the New Wiring

The most labor intensive phase is running the new NM cables through the house:

• Carefully measure and cut wires to required lengths from the spools, leaving extra for connections.
• Strip the insulation using wire strippers and bend into shape as needed before routing through walls.
• Fish stiff fish tapes through walls and cavities to pull cables from the panel to endpoints. Use lubricant to reduce friction.
• Where possible, pull all the wiring for each circuit at one go, leaving extra length at endpoints.
• Use staples to temporarily attach wiring to wall studs and joists for support while the drywall is still open.
• Avoid pulling tight bends in cables - metallic NM sheathing is rigid and can crack if bent sharply.
• Mark all wire runs at endpoints with colored tape for easy identification.

Running new home wiring is laborious but very satisfying work. Take breaks and be patient while fishing wires through framing.

Installing the Wires and Devices

After routing all the cables:

• Carefully pull out just enough wire at each box and trim excess.
• Attach the grounds to all metal boxes using green grounding screws.
• Connect hot and neutral wires to devices using push-in connectors or screw terminals.
• Use wire nuts to join similar colors from different cables together in receptacle boxes.
• Reinstall existing devices like switches, outlets and fixtures or install new ones as planned.
• Attach wall plates once everything is wired up. Label any special circuits.
• Group neutral wires together in each box and cap them with marettes.

Take photos of the wiring connections as you work. This will help with troubleshooting later on. Proper technique is important for safe and long lasting electrical connections.

Connecting the Wires to the Panel

The final stage is connecting all the new wiring to the main electrical panel:

• Organize wire bundles entering the panel and cut to proper length.
• Attach cable clamps/grommets where wires enter the panel to protect from sharp edges.
• Affix cable markings and strip insulation from ends. Keep hot and neutral separated.
• Anchor the grounds to the panel interior ground bars first, followed by the neutrals.
• Connect the hot wires last - matching wire colors to breakers where possible.
• Ensure unused breaker spaces are clearly blanked off. A missing cover can short out live power busbars.
• Add tandem or quad breakers as needed to create spaces for new circuits.
• Ensure no loose strands or exposed copper remain outside the connectors.
• Double check the tightness of each new breaker connection by gently tugging on wires. They should hold firm.

With all the wiring terminated properly, you can finally switch the main breaker back on and test each circuit one by one. Fix any loose connections that may trip breakers.

Safety Checks and Cleanup

As a final step:

• Plug in and test each outlet with a lamp to verify proper operation.
• Install wall plates and close up all holes or exposed boxes.
• Affix warning labels on any live junction boxes that remain accessible.
• Vacuum up all stray bits of old insulation and copper wire scraps.
• Dispose all old wiring safely according to local hazardous waste guidelines.

Replacing damaged wiring in an older home provides peace of mind and greatly improves electrical safety. Take it slow and be extremely cautious when dealing with live wires. Thorough planning and preparation coupled with safe installation practices will ensure your wiring upgrade project is a complete success.