How To Troubleshoot Knob and Tube Wiring (Without an Electrician)

What is Knob and Tube Wiring?

Knob and tube wiring was an early standardized method of electrical wiring used in buildings from about 1880 to the 1940s. It consists of insulated copper conductors run through protective tubes or knobs, which act as spacers to prevent contact between wires.

Some key characteristics of knob and tube wiring:

• Two separate wires - The hot and neutral wires run through separate knobs and tubes, unlike modern cables that encase both wires together. This prevents overheating.

• Open air circulation - The wires are not contained in a metal conduit or cable sheathing. This allows heat to dissipate more easily.

• Ceramic spacers - Knobs are made of ceramic insulating material to prevent any contact between wires. Tubes provide protection where wires enter boxes or pass through framing.

• No ground wire - Older knob and tube systems do not include a ground wire, making the system less safe than modern electrical systems.

While knob and tube wiring was safe when installed correctly, it can become hazardous as it ages. Fraying insulation, improper splices, overloaded circuits, and lack of grounding are concerns.

Dangers of Old Knob and Tube Wiring

There are several potential dangers associated with old or damaged knob and tube wiring:

• Fire hazard - Exposed copper conductors can arc or spark. Outdated wiring lacks modern overcurrent protection. This can overheat wires and ignite nearby combustible materials.

• Shock hazard - Damaged or worn insulation exposes live conductors. Touching these wires risks dangerous shocks. Lack of grounding removes a key safety feature.

• Weak connections - Splices connecting knob and tube wires can come loose over time. This can cause wires to overheat and poses a fire risk.

• Overloading circuits - Knob and tube systems were not designed to handle large loads from modern appliances. Overloaded circuits can overheat.

• Insurance issues - Many insurers refuse to cover homes with knob and tube wiring due to safety concerns. This can make selling or financing a home difficult.

• Difficult to repair - It can be challenging to find replacement parts and materials for obsolete knob and tube systems. Improper repairs increase risks.

The risks of knob and tube wiring grow as systems age. Periodic inspection and limited use of high-power devices can help mitigate hazards in the short term. Ultimately though, replacement provides the only reliable solution.

How to Troubleshoot Problems

Troubleshooting knob and tube wiring yourself involves several steps:

Visual Inspection

• Carefully examine wiring from basement to attic looking for common issues:

  • Cracked or damaged insulation exposing bare conductors
  • pull chains, knobs, or tubes damaged from contact with framing
  • signs of overheating like charring or discolored wires

• Watch for scorched dust or debris around knobs and tubes indicating arcing

Check Connections

• Gently tug on each wire leading into junction boxes or light fixtures

  • wires should be securely fastened without moving or feeling loose

• Look for improperly spliced connections covered with electrical tape rather than wire nuts

• Use a non-contact voltage tester to check for power. Make sure electricity reaches each fixture.

Assess Circuits and Fuses

• Identify each fuse or breaker controlling knob and tube circuits

• Note which rooms or fixtures are on each circuit

• Monitor circuits for overheating by feeling for warm fuses or tripped breakers

• Consider having an electrician evaluate the capacity of each circuit

Check Insulation

• Use a multimeter or insulation tester to measure insulation resistance

• Look for very low ohms readings that indicate breached or wet insulation

• Megger readings under 10 megohms often signal trouble

Test Hazards

• Check for ground faults using a GFCI outlet tester or receptacle

• Confirm absence of ground wires with a multimeter or circuit tester

• Check for hot neutral wires by comparing hot to neutral readings

Document and Label System

• Draw a simple diagram of the wiring routing through walls and ceilings

• Label major junction points and endpoints for each circuit

• Note any potential code violations or safety issues identified

When to Call an Electrician

While many knob and tube issues can be troubleshooted yourself, it is safest to have a professional handle any repairs or replacements. Seek electrician help if you discover:

• Exposed conductors or breached insulation

• Multiple loose connections or chronic failures

• Circuits repeatedly tripping or evidence of severe overheating

• Fuses that are under or over capacity for the wires they protect

• Lack of dedicated circuits for high load devices like stoves or air conditioners

• Any other condition you are uncomfortable attempting yourself

Replacing knob and tube wiring completely is the ideal long term solution. An electrician can assess your system's condition and outline replacement options given your home's layout and budget.

Many electricians offer special expertise working on older homes. When selecting a pro, look for:

• Extensive experience with knob and tube wiring

• Knowledge of local codes and permitting

• Availability to handle large whole-home rewiring projects

• Use of modern materials that match your home's aesthetics

Avoid attempts to simply pigtail or cap off old wiring. This leaves hazards in place rather than eliminating risks. Insist on full removal for safety.

Safety Tips for the Homeowner

When contending with older knob and tube wiring, keep these safety tips in mind:

• Never connect high load devices like dryers or air conditioners to these circuits

• Do not run extension cords across ceilings or through walls - use heavy 12 gauge or larger

• Keep insulation away from wiring to prevent overheating

• Shut off power before attempting any repairs

• Check insurance policy and confirm coverage amounts/exclusions

• Have an electrician install GFCI outlets and smoke detectors throughout home

• Turn off unneeded fuses or breakers to reduce loads

• Keep an ABC fire extinguisher handy in case of an electrical fire

• Consider turning off power to unused rooms

Periodic troubleshooting and strictly limiting use of high power devices can temporarily mitigate risks until wiring can be fully updated. But reaching out to an electrician should be your first call when dealing with any knob and tube concerns.