Electrical System Mortgage 2026: Knob-and-Tube, Aluminum Wiring, and What Lenders Require

Electrical system deficiencies are among the most common appraisal conditions on older homes. Understanding how different types of outdated or deficient wiring are treated by FHA, VA, and conventional programs helps MLOs set accurate expectations and avoid last-minute closing delays.

Knob-and-Tube Wiring

Knob-and-tube wiring was standard in homes built before approximately 1950. It uses separate hot and neutral conductors run through ceramic knobs and tubes in the framing. The wiring itself is not inherently unsafe when original and undisturbed, but age-related insulation deterioration, improper modifications, and lack of a ground conductor create risk. FHA appraisers are required to note knob-and-tube wiring when observed. Most lenders will condition the file on a licensed electrician's inspection and clearance letter confirming the system is safe and functional. More critically, homeowners insurance has become increasingly difficult to obtain for knob-and-tube homes, which itself is a lender condition since proof of insurance is required at closing.

Aluminum Wiring

Aluminum wiring was used in residential construction between approximately 1965 and 1973 when copper prices spiked. Aluminum expands and contracts differently than copper when carrying current, which can cause loose connections at outlets, switches, and breaker panels over time. Loose aluminum connections can overheat and ignite. Lenders and insurers treat aluminum wiring cautiously. Remediation options include COPALUM connectors installed at every connection point (the preferred repair per the Consumer Product Safety Commission) or pigtailing with appropriate connectors. A licensed electrician's clearance confirming the remediation method used is typically required.

Older Panels and Inadequate Service

• ✦Fuse boxes: not inherently deficient, but if the service capacity is 60 amps and the home has modern appliances, a capacity upgrade may be noted by the appraiser
• ✦100-amp service: generally adequate for homes under 1,500 square feet without electric heat; larger homes or those with EV chargers may require 200-amp service
• ✦Double-tapped breakers: two wires connected to a single breaker terminal is a fire hazard and a common appraisal note. Requires an electrician to install a tandem breaker or add a subpanel.
• ✦Exposed wiring: any wiring running exposed without conduit in finished living areas is typically flagged and conditioned