Assess the Existing Electrical System
Before beginning any rewiring project, it's crucial to understand what you're working with. Here's how I go about assessing the existing electrical system in a 120 year old home:
Look For Knob and Tube Wiring
- Knob and tube wiring was commonly used in homes built before the 1930s. It consists of single insulated wires passing through porcelain knobs and tubes.
- I check the attic, basement, and inside walls for the presence of knob and tube wiring. Its cloth insulation often deteriorates over time, posing a fire hazard.
- If knob and tube wiring exists, I hire a licensed electrician to remove it completely prior to rewiring. Attempting to modify or extend knob and tube can be extremely dangerous.
Check the Electrical Panel
- Older electrical panels often max out at 60-100 amps. Modern homes usually need 200 amps minimum.
- I look at the main electrical panel to determine the capacity and condition. Small, corroded bus bars or the presence of fuses indicate an obsolete panel.
- For major rewiring, the electrical panel will likely need upgrading to support additional circuits. This should be done by a professional.
Identify Ungrounded Outlets
- Homes built before the 1960s often lack grounding wires, which protect against shocks and fire. Ungrounded outlets only have two slots instead of three.
- Using a circuit tester, I check each outlet to see if it's grounded. Rewiring will need to include installing new grounded outlets.
Locate Existing Wiring Pathways
- Knowing where existing wiring runs inside walls and ceilings is important for strategic rewiring.
- I look for attic wiring paths that indicate outlet locations. I also gently remove select outlet covers to see how wires enter the box.
- This allows me to plan new wiring routes that leverage existing infrastructure.
Develop a Rewiring Plan
Once I understand the existing electrical system's condition, I can map out my plan:
Prioritize Required Upgrades
- Safety issues like knob and tube wiring must be addressed first. This likely requires hiring an electrician.
- If possible, I try to rewire one room or circuit at a time to spread out costs. Starting with frequently used areas can be worthwhile.
- For efficiency, I coordinate wiring upgrades with other renovations like new walls or flooring.
Choose a Realistic Scope
- Rewiring an entire house down to the studs can cost tens of thousands of dollars.
- Instead, I focus on essential upgrades like a new electrical panel, grounded outlets, lighting, and new circuits for major appliances. This still requires significant work, but costs much less.
- Doing a full rewire later remains an option if necessary.
Plan Wiring Routes
- Mapping out new wiring runs in advance saves a lot of time and holes in walls.
- I sketch where to feed wires through walls, ceiling, and floors to connect new outlets and fixtures. Accessing awkward crawlspaces early while they're open can prevent headaches.
- I mark stud locations for installing outlet and junction boxes at code-approved heights.
Select Appropriate Materials
- For safety and longevity, it's vital to use the right wiring, boxes, and connectors.
- I consult local codes and purchase extra heavy-duty NM cables and metal junction boxes. Using quality materials ensures inspectors easily sign off.
- For period aesthetics, I choose antique-style switches, plates, and Edison bulbs in certain areas.
Safely Install New Wiring Yourself
With proper planning and extreme care, homeowners can safely rewire some circuits. Here are my tips for success:
Turn Off Power and Working Safely
- Whenever accessing any wiring, I always switch off the main breaker. I then double check with a non-contact voltage tester that power is off. This is crucial.
- I wear gloves and eye protection at all times when handling wires. I avoid working alone in case an emergency arises.
Run New Circuits and Outlets
- I map out each run and pre-cut wires to correct lengths using electrical pliers. For outlets, I leave 6-8 extra inches.
- Using a fish tape, I route cables through walls and ceilings along planned paths, securing with staples as I go. I avoid over-filling wire boxes.
- I connect wires securely using wire nuts and strip gauges. Each new outlet and connection is tested to ensure tight, corrosion-free joins.
Update Lighting Fixtures
- When installing new hardwired light fixtures, I disconnect existing wires and make clean cuts with wire strippers to expose copper.
- I join new fixture wires to existing home wires with twist-on connectors, matching like-colors. Grounds connect to grounding screws or wires.
- I mark hot wires with colored tape for easy identification. This helps prevent dangerous mix-ups.
Inspect and Test Thoroughly
- Each completed circuit is tested ahead of concealment. I plug in devices and check lights at each outlet to verify proper connections.
- Once all wiring is secured behind drywall, I have mandatory final inspections done by the city electrical inspector to receive a permit sign off. Only then do I turn the main power back on.
When to Call an Electrician
While many basic rewiring tasks are doable for a diligent DIYer, some activities are best left to electricians:
- Complete removal of knob and tube wiring
- New service entrance wires and electrical panel upgrade
- Load calculations and special circuits like 220V for laundry/AC
- Final permit inspections and sign off for major projects
Proper rewiring is serious business. If a project scope exceeds my comfort level, I hire a licensed pro. Paying an expert to handle tricky parts that I can't legally or safely perform often makes sense. The last thing anyone wants is to burn a home down!