Rewiring your home can seem like a daunting task if you don't have professional electrical training. However, with the right precautions and preparations, a diligent DIYer can successfully rewire their home safely without hiring an electrician. This comprehensive guide will walk you through everything you need to know to rewire your home's electrical system on your own.
Understanding Electrical Basics Before Rewiring
Before attempting to rewire your home, it's crucial to have a solid grasp of some key electrical principles and components in order to work safely and effectively.
Electrical Current and Circuits
Electrical current refers to the flow of electrons along a conductor. In a complete circuit, the current flows from the power source through wires and devices and returns to the source. Resistance impedes the flow of current. The unit of resistance is ohms.
Voltage, Amperage, and Wattage
Voltage measures the "pressure" pushing current through a circuit. Standard household voltage is 120 volts. Amperage (amps) measures the amount of current flow. Higher amperage allows more power to flow. Wattage measures the rate of energy use. It is calculated by multiplying volts and amps.
Series vs. Parallel Circuits
In a series circuit, current flows through each component one after another. In a parallel circuit, current splits between branches with components. Home wiring uses parallel circuits so each outlet and switch function independently.
Three-Wire Cable
Most modern home wiring uses three-wire NM (nonmetallic) cable. It contains two hot wires that carry 120 volts each and a neutral wire that completes the circuit. The cable also has an uninsulated ground wire for safety.
Circuit Breakers and Fuses
Circuit breakers and fuses interrupt the circuit if there is an overload or short circuit. This protects the wires from overheating and prevents fires. Each circuit in the electrical panel should have a 15- to 20-amp circuit breaker.
Gathering the Right Rewiring Supplies
Before starting a rewiring project, assemble all the necessary supplies. This includes:
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NM cable - Match the wire gauge to the circuit size. #14 gauge is suitable for 15-amp circuits. #12 gauge handles 20-amp circuits.
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Wire strippers - A quality pair of wire strippers makes stripping insulation easy.
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Voltage tester - Essential for safely testing wires. Non-contact testers are the safest.
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Cable staples or clips - To affix wiring to studs or joists.
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Wire nuts - For connecting and capping wires. Get variety pack for different wire gauges.
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Electrical tape - Used to insulate wire connections.
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Conduit - Used to protect cable runs for some exposed areas.
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Double gang boxes - Required for outlets and switches.
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Circuit breakers - For new circuits you'll add in the panel.
Safety Gear Crucial for Rewiring
Working with electricity is inherently dangerous. Protect yourself with the appropriate safety gear.
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Electrical gloves - Insulated rubber gloves can prevent electrocution.
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Safety goggles - Protect your eyes from debris while working.
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Dust mask - Prevents inhaling dust or insulation particles.
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Work boots - Rubber soles help prevent accidental shocks.
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Headlamp - Frees up both hands for working.
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First aid kit - Have on hand for minor cuts, burns or other injuries.
Also be sure to turn off the main circuit breaker before starting any rewiring work.
Planning Your New Wiring Layout
Carefully planning the layout ahead of time will make the rewiring process smoother.
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Examine the existing wiring and make notes on the location of boxes, fixtures and appliances.
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Evaluate your needs - Make upgrades like adding circuits or increasing amperage for large appliances.
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Draw up a new plan marking lengths, wire sizes, box locations and fixtures.
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Plan cable routing through walls and ceilings to each box and fixture. Follow building codes for fill rate.
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Have an electrician review the plan if possible, to catch any errors or issues.
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Order all the necessary supplies using the plan as a guide. It's better to overestimate.
Safely Removing Old Wiring
Before installing new wiring, the old wiring must be fully removed.
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Turn off power at the main breaker before starting removal. Test wires with a voltage tester to be sure.
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Examine how existing cables are routed to understand the wiring layout.
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Disconnect wires from devices and fixtures, labeling if necessary.
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Unhook wires from the circuit breaker carefully to avoid confusion.
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Use needlenose pliers to unfasten staples or clips securing cables.
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Pull wires out carefully by hand to keep wires intact for recycling or reuse.
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Remove abandoned boxes. Patch and refinish the areas.
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Discard or recycle the old wiring properly.
Routing and Securing New Wiring
Once the old wiring is removed, you can install the planned new wiring circuits.
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Start by mounting the circuit breaker and labeling the new circuit in the panel. Shut off the main breaker again.
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Run a fish tape or long wire from the panel through walls and ceilings to guide the cable placement.
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Carefully pull the NM cable through the planned route. Don't exceed fill rate.
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Leave extra length at boxes - at least 6 to 8 inches of excess.
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Staple the cable securely along framing using approved cable clips or staples every 4-1/2 to 5 feet.
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Use protective conduit where wiring passes through masonry or is exposed.
Installing Wiring at Boxes and Fixtures
Use proper techniques for smooth wire connections at each box and fixture.
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Leave 1/2" sheathing when stripping insulation from cables. Avoid nicking the wire.
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Make sure hot and neutral wires line up correctly with the device. Consult diagrams.
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Pigtail wires for multiple connections to be certain lugs are not overloaded.
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Wrap clockwise on screw terminals. Tighten securely but avoid overtightening.
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Use wire nuts for capping unused wires. Follow torque specs for type/gauge.
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Fold wires neatly into the box, taking care to relieve strain on connections.
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Maintain polarity consistency for outlets by connecting hot wires to brass screws and neutrals to silver screws.
Testing the New Circuits
Verifying proper operation and safety is the final vital stage when rewiring.
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Keep the main breaker OFF until ready to test. Double check that all connections are tight.
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Turn the main breaker on - Then switch on the individual circuit breaker for each new circuit.
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Plug in a lamp or tester at each outlet. Turn fixtures on. Verify proper operation.
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Use a voltage tester to confirm hot and neutral wires. Check ground wires with continuity tester.
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Inspect the circuit breaker while operating connected loads. It should not trip.
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Verify acceptable voltage levels with a multimeter. Kitchen and laundry circuits should give 220 volts.
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If faults are found, turn off power and methodically recheck connections and wiring.
Calling an Electrician for Complex or Unsafe Scenarios
While many standard rewiring tasks can be DIYed safely, it's wise to call a licensed electrician for:
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Upgrading the main service panel - High voltage can kill.
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Running 220-volt circuits for stoves, dryers, etc - Requires double pole breakers
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Grounding and bonding the system per codes - Improper grounding jeopardizes safety.
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Underground wiring for outdoor lighting - Requires burial-rated wire and conduit.
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Troubleshooting mysteries like lost neutral wires - Can indicate serious unseen hazards.
Their expertise can handle the complexity and risk of these special cases.
Rewiring your home is a major project but achievable for a capable DIYer by following good planning, safe practices, and getting professional help when prudent. With diligence and care, you can renew your home's electrical system and get things wired exactly the way you want.