How to Rewire Your 150 Year Old Farmhouse Without Burning it Down

Assess the Current Electrical System

When dealing with an old farmhouse that is likely over 150 years old, the electrical system is probably quite outdated and potentially hazardous. The first step is to carefully inspect the current wiring situation. Look for:

Knob and tube wiring - This early form of electrical wiring from the late 1800s uses ceramic knobs and tubes to run wires through walls and ceilings. It's obsolete and a fire hazard.
Cloth-covered wiring - Used in the early 1900s, these wires with cloth insulation can become brittle and fray over time.
Unsafe connections - Look for loose connections, wires with insulation cracked or peeling away, overloaded outlets with too many appliances plugged in.
Any signs of scorching or burning around outlets. This indicates a short circuit or overloaded circuit.
Blown fuses - Check fuse boxes for signs of frequently blown fuses which can signal an overloaded circuit.
Exposed wires - Wires should never be exposed due to insulation damage or damage to walls/ceilings.

Take notes on all hazards found. This inspection will determine how much rewiring you'll need to do.

Develop a Rewiring Plan

Once you've assessed the current wiring situation, develop a plan for upgrades:

Decide which sections need complete rewiring (e.g. rooms still using knob and tube wires).
Determine if you will rewire room by room or if the whole house needs rewiring.
Plan on upgrading the main electrical service panel if needed. Older homes may still have 60 amp service. Upgrade to 100 or 200 amps.
Add more circuits - older homes often have fewer circuits which can overload them.
Include plans for adding more outlets, switches, and lighting fixtures. Most older homes have too few outlets.
Consider any high-power appliances you want wired in like air conditioners, kitchen appliances, washer/dryer, etc.
Create a room-by-room plan showing all outlets, switches, and fixtures. Sketch wiring paths.

Hire a Licensed Electrician

Rewiring an old home has safety risks if done incorrectly. Work with a licensed electrician to:

Obtain the proper rewiring permits for your municipality.
Have the electrician do any service panel upgrades.
Let the electrician handle any rewiring in hazardous areas like kitchens and bathrooms, or where unique skills are required.
Review your full rewiring plan with them and have them advise as needed.

What You Can DIY Safely

While the major electrical work should be handled by a professional, there are some rewiring tasks you may be able to safely DIY:

Removing old knob and tube or cloth-wrapped wiring (when wires are being fully replaced).
Installing non-metallic sheathed cable for most general wiring uses. This has flexible plastic and rubber tubing around wires and is safer for DIYers to install.
Rewiring existing light switches and wall outlets in less hazardous rooms.
Installing new lights such as ceiling fixtures, pendant lights, chandeliers, etc if the wiring is already in place.
Adding smoke detectors and carbon monoxide detectors. These are a must for an older rewired home.

Stay Safe During the Rewiring Process

When rewiring an older home, safety should be your top concern:

Turn off power at the main breaker panel before doing any work. Verify it's off using a non-contact voltage tester.
Only work on small sections at a time, turning power back on to test frequently.
Keep a fire extinguisher handy at all times.
Don't leave any wiring exposed or unattended when walls/ceilings are opened up.
Use safety gloves and goggles when dealing with electrical.
Collect and properly dispose of old wiring so it doesn't become a hazard.
Check smoke detectors function after power is turned back on.

Follow good safety practices and partner with a licensed electrician on major rewiring tasks, and you can successfully rewire your old farmhouse without burning it down!