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90 year old house with knob and tube

We have just bought a home with knob and tube wiring and a 100 amp panel. We would like to add outlets and some ceiling fixtures to the bedrooms on the second floor. The house is three floors. Is there any way to wire these areas without taking out the entire ceiling, etc.? :confused:

Re: 90 year old house with knob and tube

A talented electrician who's willing to take time to think about what he's doing can fish new wires through old walls with minimal damage. You'll probably have some minor repairs to do, but it shouldn't require tearing out the walls & ceiling.

Hiring an electrician with a lot of experience in old houses (and whose references are happy with the workmanship) may be a lot cheaper than having to do major repairs to the walls & ceiling.

If you're doing it yourself, two tools that will help you: an electrician's fish tape, and fiberglass rods. These will help you to "fish" the wires through places without tearing it all up. Another tool that's helpful is a long, flexible drill bit (these are around 4-6 feet long). Greenlee's models are called something like "D'VersiBIT". The idea is that you can drill through the top or bottom plate on a wall using the existing outlet box hole for access.

You should have the wiring inspected; expect to pay for this service. A lot of the old knob-and-tube wiring has crumbling insulation, but if the insulation is good then it's not necessary to replace it.

Re: 90 year old house with knob and tube

It's best to check your local codes before you do anything. In some areas knob & tubing wiring must be changed when you do new wiring or renovation work.

Calcats ;)

Timothy Miller
Re: 90 year old house with knob and tube

Howdy, yes you can do rewiring without removing the walls and ceilings. I just re wired my 105 year old home. The walls of you home are likely balloon construction so installing new wiring by attaching it to the old and pulling the new to the existing outlet will probably work very well. Gaining access from the attic to rewire the upper level will aid in the work. Some areas small holes will need cut to access the ceiling/ wall for running wire. These can be patched or covered with ceiling trim molding. And siring from the basement( if you have one ) allows allot more access. It was a huge job and now i know why the electrical bids were so high. With the electrical panel cover removed an electrician can see if any of the old wiring was replaced when the 100 amp panel installed. Having a 100 amp panel is a upgraded panel for an old home.

Bill Park
Re: 90 year old house with knob and tube

Adding outlets is not hard, just home-run them to the basement. Warning... do not cut any knob and tube wiring. You may end up killing other outlets or fixtures, because of the way that knob and tube is wired. The ceiling is another issue. You'll probably not find any boxes in the ceilings, and you'll have to cut out lumber that spands studs to make a place in which to put boxes. I opted to leave the ceiling alone in most locations, adding boxes and new fixtures, but living with the switch arangements as built.


Old # 7
Re: 90 year old house with knob and tube

We also just bought an 1880's house that had been owned by one family since built. 3 finished stories with partial basement and original maple floors throughout. Plaster and paint are in great shape and we would like to avoid damaging it as much as possible. It's knob & Tube but the wiring is in great shape. I'm told in Wisconsin that if the electrician sees it, they must remove it. Has anyone used remote switches to help reduce the amount of damage? Also can the holes be patched using drywall & mud or plaster only?


Re: 90 year old house with knob and tube

Yes there are ways to patch the holes with patching plaster, hydrocal, speed set, mortar.....

Knob and tube may not be covered by your insurance. I'd check that out before assuming anything AND get it in writing.

If you knew how dangerous / scary / impractical K&T wiring is you'd be pulling it out yourself. Make a long term plan on remodeling that includes re-wiring to allow this grand home to be brought into the 21st century.

Re: 90 year old house with knob and tube
HoustonRemodeler wrote:

Make a long term plan on remodeling that includes re-wiring to allow this grand home to be brought into the 21st century.

Agreed. It's not just the electrical wiring that needs to be brought up-to-date, but also plumbing. The pipes are probably old and likely to begin leaking at any time; that will cause more (and more expensive) damage than cutting holes in the walls to replace pipes and wires.

At the same time, you'll probably want to install some "21st century" wiring such as telephone, Ethernet, cable TV, central sound (and maybe even central vacuum). When you install these, make them all home runs to a single central structured wiring distribution panel -- don't daisy chain. Use CAT6 for both Ethernet and phone -- that way, if you need to convert a phone line into an Ethernet line all you have to do is change the jack.

For the computer you may be thinking of using WiFi, but I'll tell you right now that plaster and lead paint block WiFi signals. I recommend wired networking wherever possible; it's faster and more reliable than WiFi.

Old # 7
Re: 90 year old house with knob and tube

Thanks for the input, smart ideas to include the cable / cat 6. I hadn't thought that far ahead. K&T isn't covered by our insurance, I have 60 days to bring up to compliance. My hope is to limit the amount of holes I need to make to complete the upgrade. I haven't explored the plumbing lines yet. I suppose it's better to get all the dust out of the way at one time.

Thanks again

Re: 90 year old house with knob and tube

Two cautions, one you can not insulate with K&T wiring, if you do plan on insulating rewire first, and two, connecting to K&T wiring, where it is permitted, MUST be done properly it is far better to always run new wiring rather than connecting to K&T wiring.


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