You may have heard that Minnesota adopted a new electrical code, and wondered whether the knob and tube in your walls just became a problem. The short answer: it didn’t. A new code edition governs new work. It doesn’t make the wiring you already have unlawful.
At Northloom Minneapolis Knob and Tube, we rewire houses under permit in Minneapolis and St. Paul. This news note explains what the change means for your old wiring, and for a rewire you might be planning.
Does my knob and tube have to come out now?
No. Electrical codes govern an installation when it’s made. Knob and tube that was installed correctly under the rules of its time isn’t made unlawful by a later edition, and leaving it alone isn’t a code violation.
What the new edition does affect is anything you change. Here’s how it plays out:
| Your situation | What the new edition does |
|---|---|
| Knob and tube left alone | Nothing |
| Knob and tube extended | Allowed only as an extension of an existing installation; never in insulated spaces |
| Circuits replaced in a rewire | Your new circuits meet the new edition in full |
| Rewire with a permit filed before the change | Stays under the edition in effect when it was filed |
The code’s article on concealed knob and tube stays as it was: extensions of existing installations only, and no use in hollow spaces filled with insulation around the conductors.
What exactly changed?
Minnesota adopted the latest edition of the National Electrical Code statewide, without amendment. It governs permits filed from its effective date in mid-August.
- Edition
- The latest National Electrical Code, adopted statewide.
- Amendments
- None; Minnesota adopted it as published.
- Effective
- For permits filed from the effective date; earlier permits stay under the previous edition.
- St. Paul
- The city enforces the same edition on its own permits.
What will my new circuits include?
When we rewire your house, the new circuits are built to the edition in effect when the permit is filed. In practice, that means:
- Grounded cable to every device
- Arc-fault protection on circuits serving living areas
- Ground-fault protection near water
- Kitchen small-appliance circuits, a bathroom circuit and a laundry circuit
- Boxes and devices sized and listed to match
Most of those requirements have been in place for several editions; each new one refines them. Your written scope lists the protection each new circuit gets, so you can see it before work starts.
My rewire is already permitted. Does anything change?
If your permit was filed before the effective date, the earlier edition applies to your job. If it hasn’t been filed yet, the new edition applies. Whoever is quoting your work should be able to tell you which edition the price assumes; ours says so in the scope.
So what actually pushes people to replace knob and tube?
For most houses, it won’t be the code change. It’s an insurer asking whether any knob and tube is energized, a buyer’s inspector noting it, or an insulation contractor who won’t work around it. Those are what usually bring the question to your door. The legality guide covers how those pressures relate to the code.
What stays the same?
Several things that matter to you as the owner of an older house don’t move with a new edition:
- Minnesota’s homeowner permits are still limited to an owner living in a single-family house.
- The request for inspection still goes in at or before the start of work, and an inspector still sees the wiring at rough-in before anything covers it.
- The state’s fee for a Minneapolis rewire, $191 for 15 to 30 circuits in an existing one-family home, comes from Minnesota’s fee rules, not the code edition.
And the practical questions, whether your knob and tube is live, whether your insurer will accept it, whether your attic can be insulated, get answered by tracing your circuits, not by reading the code.
Can I insulate around knob and tube under the new code?
No, and that hasn’t changed. The code’s bar on concealed knob and tube in insulated spaces carries forward. If you’re planning to insulate an attic or walls, which in a Minnesota winter is often the point of the whole project, the wiring still has to be settled first. Xcel Energy’s insulation rebates, for customers who heat with Xcel gas or electricity, follow once it is.
Who enforces the code where I live?
That depends on your city, not your mailing address. The Minnesota Department of Labor and Industry inspects electrical work in Minneapolis and many suburbs; St. Paul’s Department of Safety and Inspections enforces the same edition in the city; and about 66 Minnesota cities run their own electrical inspection. The permit guide explains each. Questions about your house: (612) 509-6597.