Project Overview
Location: Portsmouth, New Hampshire Scope: 100 to 200 amp service upgrade, partial home rewire, full knob and tube elimination Team: Eric, Troy, Justin, and Ryan — Loyal Lab Electric and Generators Service Area: Dover, Portsmouth, Rochester, Somersworth, Exeter, Stratham, Rye, Newington
Portsmouth is one of the oldest cities in the country. A lot of the homes here and throughout the broader area were built in an era when knob and tube wiring was standard. This job is a good example of what we find in older Seacoast homes and why the problem is almost always bigger than it looks from the outside.
The Situation
This customer bought their Portsmouth home a couple of years ago and had a suspicion there might be old wiring somewhere in the house. From the outside, nothing flagged it. Modern light switches, updated fixtures throughout — it looked like the home had been maintained and updated over the years.
It wasn’t until we got into the basement that we found knob and tube running throughout the home.
This is one of the most common scenarios we see in Dover, Portsmouth, Rochester, and Somersworth. Previous owners do partial updates over the years and the old wiring stays buried in the walls. From a visual inspection at ground level, the house looks fine. The danger is hidden.
We also found a fuse box tucked away that the current owner had no idea existed. That discovery is what led us to go through the entire home systematically. Almost every knob and tube replacement we have done has had some kind of cover-up attempt, whether intentional or not. Someone removes what is visible in the basement and attic because it is accessible and easier to reach. The wiring inside the walls stays.
That is the most hazardous part. Most electrical fires don’t start with wiring that is exposed in a basement. They start with old, weakening connections buried inside insulated walls and ceilings where heat has nowhere to go.
What Knob and Tube Wiring Actually Is
Knob and tube gets its name from two components used in its installation. The tubes are small ceramic insulators threaded through drilled holes in the joists to protect the wire as it passed through framing. The knobs were ceramic anchors nailed into the wood that allowed the wire to change direction.
The wire itself is a single conductor with no outer jacket and no ground wire. Over time, especially in homes where the system has been modified or extended by different hands over the decades, the insulation becomes brittle. A wire that held up for 60 years can crack and expose bare copper with very little physical stress. That is how fires start.
If you want to do a basic check yourself before calling an electrician near you, go to your basement and attic. Look for ceramic knobs nailed into the framing and small ceramic tubes running through the joists. What you find there is only part of the picture. What is inside your walls is the part that matters most.
The Cover-Up Problem
We want to be direct about something we see constantly in homes across Dover, Portsmouth, Exeter, and Rochester. When homes are sold, knob and tube in visible areas like the basement and attic sometimes gets removed or disconnected to pass inspection or avoid flagging a buyer. The wiring inside finished walls and ceilings stays in place because removing it is invasive and expensive.
A buyer or home inspector walking through a house may see no obvious signs of knob and tube. Updated switches, modern fixtures, nothing flagged in the basement. The house looks clean. The real problem is sealed behind drywall.
If you are buying an older home anywhere in Rockingham or Strafford County, an electrical assessment by a licensed master electrician is worth doing before closing. Not a visual inspection. An actual investigation.
The Hidden Junction Box Problem
Here is something most homeowners and even some home inspectors overlook entirely. If your home has knob and tube wiring and someone replaced a light fixture at any point, there is a very good chance that light does not have a proper junction box behind it.
Knob and tube era wiring used either a small mounting point called a fixture hickey or no box at all. When a homeowner or handyman swaps in a new fixture, they almost never install a proper junction box to contain the splices. Adding a correct box to knob and tube wiring is technically challenging work. Most unqualified people skip it entirely.
What that leaves you with is an open splice inside your ceiling, hidden behind a fixture that looks perfectly normal from below. It is one of the most overlooked hazards we find on these jobs and another reason a visual inspection alone is not enough.
The Work
This job required a full panel replacement and service upgrade from 100 to 200 amps. The homeowner has plans for mini splits and an EV charger down the road, and the existing service could not support that load regardless of the knob and tube situation. Combining the service upgrade with the rewire was the right call financially. One disruption instead of two.
Troy handled the panel swap while Justin, Ryan, and the rest of the crew worked through the rewire. Most of the knob and tube was isolated to the first and second floors. The first floor is typically the most manageable. The second and third floors are where rewires get complex and time-consuming.
This job required access points throughout the home. That is not always the case. We have done full rewires without making a single extra hole, but it depends on the layout, the framing, and what is inside the walls. We coordinate with a patch crew to come in after us so walls and ceilings are restored when the electrical work is complete.
The Result
The home now has a 200 amp service, fully grounded modern wiring throughout, and no remaining knob and tube. The hazard is gone.
The practical outcomes for this Portsmouth homeowner:
Insurance coverage restored. Many carriers in New Hampshire will not write a homeowners policy on a property with active knob and tube wiring. Some will write the policy but exclude electrical fires. Removing it restores full coverage and in many cases lowers the premium.
Future projects are now possible. Mini splits, an EV charger, additional circuits — the 200 amp service can handle all of it.
Clean record for resale. When this home eventually sells, there are no surprises waiting in the walls.
Watch the Full Project Video
Want to see the job from start to finish? We documented the whole thing on our YouTube channel.
Watch: Knob and Tube Wiring Replacement in Portsmouth NH
If You Think You Have Knob and Tube
If your home was built before 1950, there is a reasonable chance some knob and tube is still in there. You may not be able to see it. That does not mean it is not there.
The only way to know for sure is to have a licensed electrician take a look. We hold NH Master Electrician License 13956 and ME Master Electrician License MS60021263. Every job we do is assessed and performed by a licensed master electrician. We serve Dover, Portsmouth, Rochester, Somersworth, Exeter, Newington, Rye, Stratham, and the surrounding Seacoast area.
Call us or fill out the form below to schedule an assessment.
