How to Safely Install Old Knob and Tube Wiring


Knob and tube wiring was commonly used in homes built before the 1940s. This old electrical system utilizes porcelain knobs and tubes to run wiring through open walls and ceilings. While knob and tube can still be safe if properly maintained, it does pose risks due to lack of grounding and insulation. If your home contains knob and tube wiring, you may wish to update your electrical system. However, in some cases, you may need to install additional knob and tube wiring. This article will discuss how to safely install knob and tube wiring in an old home.

Dangers of Knob and Tube Wiring

Before installing new knob and tube wiring, it's important to understand the potential dangers:

While I don't recommend installing knob and tube wiring in new construction, you can safely build onto an existing system by taking the right precautions.

When Is It Acceptable to Install New Knob and Tube Wiring?

There are a few cases when it may be acceptable to install new knob and tube wiring:

Always check your local electrical code before proceeding. Use new knob and tube only as a last resort when rewiring is impractical. Favor safer wiring methods whenever possible.

Safety Precautions When Installing Knob and Tube

If you decide to install new knob and tube wiring, take these important safety precautions:

Use Appropriate Materials

Limit Fire Hazards

Increase Safety

By following these guidelines, you can install new knob and tube wiring as safely as possible. However, upgrading to modern wiring should still be a priority when feasible.

Step-by-Step Installation Guide

If you decide to install new knob and tube wiring, follow these steps carefully:

1. Plan the Wiring Layout

2. Install Insulators

3. Run and Connect Wires

4. Attach Devices and Covers

5. Test and Troubleshoot Wiring

By taking the proper time to plan and install the wiring methodically, you can help reduce risks when adding knob and tube circuits.

When to Call an Electrician

While a skilled DIYer can install knob and tube safely in many cases, it's best to call a professional electrician for:

Consult with a licensed electrician before tackling projects beyond your skill level. Most electricians can also provide quotes for rewiring if upgrading the electrical system is feasible.


While knob and tube has its limitations, following these guidelines will allow you to safely install and integrate new knob and tube circuits as a temporary fix when upgrading the full electrical system is not yet feasible.