The Truth About Knob and Tube Wiring

I've been hearing a lot of debate lately about knob and tube wiring. As a homeowner with knob and tube wiring in my 100-year old house, I decided to do some research to find out the truth about this old electrical system. Here's what I learned:

What is Knob and Tube Wiring?

Knob and tube (K&T) wiring was an early standardized method of electrical wiring used in buildings in the United States from about 1880 to the 1940s. It consists of single insulated copper conductors running through ceramic knobs and tubes, which provide protection and structural support.

Some key features of knob and tube wiring:

• Two separate wires - one for hot and one for neutral
• Wires are separated by 4-6 inches to prevent overheating
• Knobs and tubes provide air space for cooling and insulation
• No ground wire (not up to modern electrical code)

While knob and tube was a major improvement over previous wiring methods, it has been obsolete for decades. Still, I was surprised to learn how many older homes still have at least some knob and tube wiring.

Is Knob and Tube Wiring Dangerous?

This is the biggest debate around knob and tube wiring. Opinions seem to be divided.

Some electricians claim knob and tube is inherently unsafe, pointing to the lack of grounding, insulation breakdown over time, and fire risks. Their advice is to replace it entirely.

Others argue that knob and tube can be perfectly safe if properly maintained. The key risks they cite are:

• Insulation breakdown - can lead to shorts and fires
• Modification over the years - safety gaps and separations may have been compromised
• Overloading circuits - exceeding recommended capacity for the wire size

The condition of the wiring, rather than the type itself, determines the safety. Well-maintained knob and tube with nooverloads or improper modifications can function safely for many more years, proponents claim.

Problems and Limitations of Knob and Tube Wiring

While it may be possible to use knob and tube wiring safely, I found there are some downsides and limitations to be aware of:

• Fire hazard - lack of grounding and old insulation increase risk
• Insufficient for modern loads - lighting, appliances, electronics
• Difficult to modify or expand - can't tap new wires from K&T lines
• Insurance issues - some won't cover houses with K&T wiring
• Reduced property value - many buyers wary of knob and tube
• Safety concerns - no GFCIs or AFCIs without full rewire
• Inaccessible wires - difficult to inspect condition in walls

The wiring simply wasn't designed for our energy usage today. Even if maintained well, it may not be adequate for powering a modern home.

Replacement Options and Cost

If you decide to replace knob and tube wiring, there are a few options:

• Full rewire - replace all K&T wiring - $8,000-15,000
• Partial rewire - replace only where needed - $2,000-5,000
• Pigtailing - splice new wiring to old - $1-3 per outlet

Rewiring a whole house gets very expensive. Prioritizing the oldest, most used circuits first can help manage costs. Some homeowners also pigtail new wiring to outlets and fixtures to avoid a full rewire.

No matter what, I'd advise having a licensed electrician assess your specific situation. There are often ways to improve safety affordably without incurring huge costs all at once.

Final Thoughts

While newer wiring is undoubtedly safer, K&T wiring that's still in good condition can function decently for low-load circuits. But problems and limitations eventually arise. My takeaway is:

• Maintain it meticulously if keeping K&T wiring
• Prioritize high-load and fire-prone areas for replacement
• Consider partial upgrades over time to spread out costs
• Always use a licensed pro when modifying or expanding

With the right precautions, knob and tube wiring doesn't have to be an emergency. But upgrading does provide much greater capacity, safety, and peace of mind in the long run. My plan is to start budgeting to replace the oldest and most concerning sections first.