Common Electrical Defects Found in Buildings

Electrical defects constitute one of the main sources of risk in residential buildings, potentially causing fires, electrocution, and significant property damage. During a pre-purchase inspection, your ability to identify these common problems protects your clients against potential dangers and unexpected repair costs. Recognizing typical defects also allows you to formulate appropriate recommendations and clearly delineate situations requiring qualified electrician intervention.

This guide presents the most frequently encountered electrical defects during residential inspections in Quebec, associated risks, and best practices for documenting and reporting them in your reports.

Frequently Observed Wiring Defects

Electrical wiring problems represent a significant portion of observed defects, particularly in older buildings or those that have undergone modifications over time.

Obsolete or Inappropriate Wiring

Knob and tube wiring, common in homes built before the 1950s, constitutes a major defect when still in service. This wiring type offers no grounding, deteriorates over time, and presents increased fire risks, particularly when covered by thermal insulation that prevents heat dissipation.

Aluminum wiring, used in the 1960s-1970s, also poses problems. Aluminum oxidizes and expands differently than copper, creating loose connections that overheat. Poorly executed aluminum-copper connections represent particularly high fire risk. If you identify this wiring type, recommend evaluation by qualified electrician specialized in aluminum repairs.

Damaged or Poorly Protected Wiring

Visibly damaged cables - cracked, frayed, or missing insulation sheath - constitute immediate electrocution and fire danger. Carefully document their location and recommend urgent correction.

Unprotected wiring in exposed areas (basements, garages, crawl spaces) should be reported. Codes generally require mechanical protection (rigid conduit or metal armor) in these locations to prevent accidental damage. Lack of this protection constitutes common non-compliance.

Protection and Grounding Problems

Deficient or absent electrical protection systems represent major safety risks that every inspector must identify.

Absence or Failure of Grounding

Inadequate grounding constitutes one of the most common defects in old buildings. Two-hole receptacles (ungrounded) in bathrooms, kitchens, and other locations requiring GFCI protection represent electrocution risk.

Also beware of three-hole receptacles installed on ungrounded circuits - a dangerous practice giving false security impression. A simple receptacle tester reveals these situations. Grounding protects against electrical shock by offering a path of least resistance to ground in case of equipment failure.

Missing Ground Fault Protection

Absence of ground fault circuit interrupters (GFCI) in required locations constitutes frequent non-compliance. Current codes require this protection in bathrooms, kitchens (near sinks), garages, unfinished basements, crawl spaces, and exterior.

GFCIs protect against electrocution by detecting minimal current leaks (as low as 5 milliamperes) and cutting power in a fraction of a second. Their absence in humid or exterior areas exposes occupants to serious risks, particularly in presence of water or moisture.

Obsolete Equipment and Panels

Outdated or end-of-life electrical components represent failure risks and often require complete upgrade.

Fuse Panels and Problematic Panels

Functional fuse panels don't necessarily constitute a defect, but their limited capacity (typically 60 amperes) often proves insufficient for modern needs. Additionally, using oversized fuses to avoid frequent trips creates overheating risks.

Certain panels recognized as problematic - notably Federal Pacific (FPE) with Stab-Lok breakers, and certain Zinsco/Challenger models - present high failure rates. These panels may not trip correctly during overload, creating fire risk. Their identification warrants replacement recommendation by qualified electrician.

Defective Breakers and Connections

Breakers showing overheating signs (discoloration, burning smell, deformed housing) should be reported as requiring immediate replacement. Loose or corroded connections in the panel create excessive resistance, generating heat and fire risk.

Double taps (two wires on a breaker designed for one) constitute common code violation. This practice creates overheating and breaker failure risks. Each circuit should have its own dedicated protection, except for breakers specifically designed to accept two wires.

How to Report These Defects in the Report

Appropriate documentation of electrical defects protects your liability while adequately informing your clients about risks and necessary corrections.

Clear and Factual Wording

For each identified defect, specify exact location, problem nature, associated risk, and recommendation. For example: 'Knob and tube wiring observed in crawl space and visible from basement. This wiring type is obsolete and presents increased fire risks, particularly in presence of thermal insulation. Recommend comprehensive evaluation by licensed electrician and replacement of this wiring per codes in effect.'

Use accessible language while maintaining technical rigor. Avoid excessive jargon, but don't simplify to the point of minimizing real risks. Terms like 'fire risk,' 'electrocution risk,' or 'non-compliant with current codes' clearly communicate severity without creating unnecessary panic.

Prioritizing Defects by Severity

Clearly distinguish major defects requiring immediate correction from recommended improvements for compliance with current standards. Damaged wiring exposing live conductors constitutes immediate danger, while absence of GFCI in unfinished basement represents non-compliance to correct but without critical urgency.

For situations presenting significant risks, also refer to best practices for presenting deficiencies in your inspection reports to protect your professional liability.

When to Recommend a Qualified Electrician

Certain situations exceed the scope of a visual inspection and require licensed electrician expertise for thorough evaluation and appropriate corrections.

Systematically recommend an electrician for:

• Any obsolete wiring (knob and tube, aluminum, cloth)
• Electrical panels recognized as problematic (FPE, Zinsco)
• Signs of overheating or damage to main panel
• Visibly damaged wiring or exposed live conductors
• Generalized absence of grounding or GFCI protection
• Apparently non-compliant or dangerous electrical modifications

Always specify that your inspection constitutes a general visual assessment and that an electrician can perform more thorough testing, open sections for detailed inspection, and prescribe code-compliant corrections. This distinction protects your liability while directing client to appropriate resources.

Vigilance in identifying common electrical defects protects your clients against serious risks while demonstrating your professionalism and domain knowledge. Keep your skills current on electrical codes in effect, rigorously document your observations, and never hesitate to recommend specialized evaluation when the situation warrants it. Your expertise in this crucial area directly contributes to occupant safety and preservation of your clients' real estate assets.