How to Troubleshoot Old House Wiring
As a homeowner with an older house, you may encounter issues with outdated or faulty wiring that can lead to safety hazards or electrical malfunctions. Troubleshooting and understanding your home's electrical system is crucial for detecting and resolving wiring problems. In this comprehensive guide, I'll walk you through the key steps for troubleshooting old house wiring to help you address problems, make repairs, and update your electrical system.
Evaluate the Age and Type of Wiring
The first step is determining the age and type of wiring installed in your home. Older homes often have outdated wiring that may not meet modern electrical codes and can pose safety risks.
- Homes built before 1930 likely have knob and tube wiring. This primitive wiring runs through ceramic knobs and tubes and lacks grounding. It needs replacement.
- Homes built from 1930-1950 may have cloth-covered NM cable (nonmetallic sheathed cable). This has rubber or cloth insulation that dries out and cracks over time.
- Homes built from 1950-1970 typically have an early form of plastic-sheathed NM cable. While safer than cloth wiring, the insulation still degrades.
- Copper wiring started becoming common in homes in the 1960s. It offers improved safety and reliability.
- Aluminum wiring appeared in some homes in the 1960s and 1970s but is prone to overheating issues.
I recommend having a qualified electrician inspect and date the wiring if you are unsure of the type. This will inform you if upgrades are needed.
Inspect the Electrical Panel
The condition of your home's electrical panel can provide important clues about your wiring system.
- Look for a fuse box, which is obsolete and needs upgrading to a modern breaker panel. Fuse boxes lack circuit protection.
- Check for rust or corrosion in the panel, which can indicate moisture damage to wires.
- Determine if the panel provides sufficient amperage for your home's needs. 100 or 150 amps may be inadequate for newer appliances and electronics.
- Overheating signs like a burnt smell indicate the panel may be overloaded and needs repairs.
- An absence of grounding wire points to outdated, unsafe wiring without proper grounding.
Calling an electrician to assess the panel is wise if you notice any of these issues.
Inspect Electrical Outlets and Fixtures
Outlets and light fixtures throughout your home provide more clues about wiring:
- Two-prong outlets lack a ground wire and likely indicate knob and tube or cloth-covered NM cable wiring. This needs replacement.
- Check for outlets and switches that are loose, damaged, overloaded, hot, or sparking. These warn of unsafe, faulty wiring conditions.
- Flickering lights, buzzing sounds from switches or outlets, or dimming lights when appliances turn on indicate wiring problems like loose connections.
- Warm outlets or lights dimming when appliances start suggest the wiring lacks sufficient amps.
- Brittle, cracked, melted insulation around wiring points to deterioration and risk of short circuiting.
Documenting all lighting and outlet issues will help an electrician pinpoint wiring failures needing correction.
Check for Hacked Wiring Jobs
Sometimes previous homeowners take DIY electrical projects too far. Look for signs of amateur wiring jobs:
- Outlets or light switches nailed into the wall without a box
- Frayed, exposed wires jerry-rigged with electrical tape
- New outlets chained off existing outlets rather than running wire through walls
- Mismatched brands and colors of wiring that indicate piecemeal additions
Hacked, bootleg wiring is hazardous and needs removal by a professional to avoid safety hazards like short circuits and fires.
Consider Rewiring with NM Cable
If your old home wiring checks several of the warning flag boxes, a full rewiring may be your best and safest option:
- NM cable (nonmetallic sheathed) provides modern, up-to-code copper wiring with proper grounding.
- A licensed electrician can run new cable through walls, attics, and basements and install a new breaker panel.
- Though not essential, upgrading to 200 amp electrical service provides capacity for today's energy demands.
- Rewiring an entire house can cost $8,000-$15,000 but is a smart investment in safety.
Seek quotes from several electricians if rewiring the entire home seems advisable.
Make Targeted Upgrades and Repairs
If a full rewiring isn't feasible, make strategic upgrades:
- Replace any knob and tube or cloth-covered NM cable, especially near water sources.
- Reroute extension cord wiring to code-compliant NM cable circuits.
- Upgrade the main service panel to 200 or 400 amps if needed.
- Run grounding wires and upgrade two-prong outlets to GFCI three-prong outlets.
- Use AFCI (arc-fault circuit interrupter) outlets to prevent fires.
- Add more circuits to reduce outlet overloading.
- Fix loose, damaged outlets and switches.
Making key targeted repairs reduces risks while spreading costs over time.
Maintain Safe Practices
Regardless of your home's wiring state, following safe electrical practices prevents hazards:
- Shut power off at the breaker when inspecting or doing electrical work.
- Use plastic outlet covers to prevent shocks.
- Avoid overloading outlets. Power strips help prevent this.
- Don't run extension cords long term.
- Use surge protectors to protect electronics.
- Check smoke and CO detectors to stay alert to electrical dangers.
- Turn off and unplug appliances during electrical storms to avoid surges.
Staying vigilant is vital whether you fully rewire or make limited repairs.
When to Call an Electrician
Some wiring scenarios require calling a licensed electrician:
- You lack the expertise to safely troubleshoot problems.
- The main service panel needs upgrading.
- Knob and tube wiring or cloth NM cable must be replaced.
- New wiring circuits are needed.
- Grounding issues are discovered.
- Major hazards like damaged insulation or sparks occur.
Let a pro handle complex, hazardous electrical issues. They have the knowledge to fix them safely.
Old house wiring requires diligence to ensure safety and functionality. Evaluate your wiring type, inspect fixtures thoroughly, avoid overloading circuits, and make strategic upgrades where possible. Seek professional assistance when needed. Staying informed about your wiring helps minimize fire and shock risks. With vigilance and proper improvements, your old home's wiring can stay current and safe.