Questions about rewiring an old house.

[Jettavr666]

So I am looking to replace the rest of the knob and tube in my 1936 colonial home. The knob and tube is actually untouched and in perfect condition which is why I have not done anything with it yet. All new wiring that was done completely replaced the old knob and tube, and was in no way integrated with the old wiring. To keep the old knob and tube safely in service I put it all on downgraded circuits (from 20amp to 15 amp) and on Arc fault interrupters. However this has also caused some nuisance trips and because it’s an old house many rooms are on the same circuit, which makes things difficult when there is a trip. The panel is new with plenty of space so that is not an issue

I am looking to do the rewiring room by room, and I am looking for the easiest way to do this. The house has original lath and plaster walls in great condition so I don’t want disturb them too much. I am thinking that for some rooms I can remove the baseboard, and fish the wires behind there. I am looking to keep the original outlet locations because for the most part there are plenty. Each room will be on its own outlet circuit, but what about lighting circuits, can they be combined?

So in a nutshell:

*how do i make this easier
*what all should i know
*how can i avoid large wall holes
*what about lighting circuits
*ANYTHING ELSE!


Any ideas on how to make this easier are appreciated. Also house in in Pittsburgh PA, so things like conduit are not needed. but any other specific code items are appricated

[Phatbastard]

Your fundamental issue is going to be access. Do you have an unfinished basement and attic?

When I did mine I had full attic and basement access with some good wire chase possibilities. It still sucked because of the electrical boxes. You have to get strain reliefs on all your wires where they enter boxes either by cable clamps on the boxes or nailing off the romex within 6" (I think) of the box. That means you need to get the box out of the wall - I don't think there are strain reliefs that go inside the box. So, in order to get the boxes out you have to pry them away from their attachements, typically nailed to wall studs. I destroyed the carp out of my surrounding plaster. After trying to be clean about it for a few boxes, and failing, I just ended up cutting 1' squares out everywhere and patching up with sheetrock.

I spent as much time doing rock work as the rewiring. I can't imaging how much of a cluster fuq it would have been if I had a finished attic - like I do now - or finished basement.

[Jettavr666]

Your fundamental issue is going to be access. Do you have an unfinished basement and attic?

When I did mine I had full attic and basement access with some good wire chase possibilities. It still sucked because of the electrical boxes. You have to get strain reliefs on all your wires where they enter boxes either by cable clamps on the boxes or nailing off the romex within 6" (I think) of the box. That means you need to get the box out of the wall - I don't think there are strain reliefs that go inside the box. So, in order to get the boxes out you have to pry them away from their attachements, typically nailed to wall studs. I destroyed the carp out of my surrounding plaster. After trying to be clean about it for a few boxes, and failing, I just ended up cutting 1' squares out everywhere and patching up with sheetrock.

I spent as much time doing rock work as the rewiring. I can't imaging how much of a cluster fuq it would have been if I had a finished attic - like I do now - or finished basement.

basement is unfinished and attic is partially finished area near roofline has knee walls that is unfinished. However the third floor has already been completely rewired, as has the kitchen (gutted and redid in 2009)

[barry2952]

I rewired hundreds of HUD homes back in the '70s. I've experienced just about every type of construction known. Your home is the easiest to rewire because of the unfinished basement. The only hard part are switch legs.

All stick-built homes have a hollow space between interior walls. You just have to know where to drill to get a wire to where you want an outlet.

Envision your interior wall with a base plate made of a 2 x 4 on the flat. The studs are 16" on center so you have a space you need to hit from below that's 14 1/2" long by 3 1/2" wide. That's your target. Studs can be located by tapping on the wall or using a stud-finder. There is no need to remove the base molding. I've never had to do that. What you can remove is the shoe molding to drive long nail right below where you want an outlet or switch. It's best to pick a location where one wire will feed an outlet on either side of the wall.

Once you drive the nail most of the way in go in the basement and find the shiny nail sticking through the floor, into the basement. If you measure about 2 1/2" from that nail and drill up you will be in the hollow space of that wall. If you're unclear of the orientation of the wall above drive a nail on the other side of the wall and split the difference between them to center the drill on the space above.

I had a journeyman that I worked under that wished he had driven the second nail as he found a shiny nail, but it was the wrong one. He ended up drilling into the lowest drawer of a dresser. When he figured out what he had done he opened the bottom drawer to find a massive circle of twisted dress shirts. I had to .

Outlets on the outside walls are a little tougher to do, requiring an 18" ship auger. That's because the trusses sit on top of the concrete or block wall, meaning that the outside wall you want to get into is about 8 inches away, requiring an angled hole. In this case you want to drive a nail at the baseboard again. This will mark where the drill bit will have to start to get into the wall space above when drilled at a 45° angle to clear the foundation. You'll be drilling up through a basic floor plank of 3/4" and a 2 x 4 which is over an inch and a half on an old house. By the time you penetrate the top of the base plate the hole will be at the rear of the space.

Finding walls in the attic is easy as the trusses sit directly on the top plates, made of 2 2x4 on the flat. The lower layer is so you can build a complete wall and the second is to give it strength and to overlap onto adjacent walls to tie everything together.

Since the attic beams sit on these walls they are clearly visible under the insulation. You can locate where you want to drill down by simple measuring off know corners below. The outside walls near the eaves are often difficult to drill on low-pitched walls but can be drilled straight down with a right-angle drill and stubby ship auger with a screw feed.

Just remember to give all your wiring 2" of mechanical protection. Simple stapling at long runs and direction changes should suffice. I could draw you pictures if you need them.

Edit, on the subject of lathe plaster. I would have loved to have had today's rotary tools. Hand saws made quite a bit of work for the plasterers that followed us. Done properly the rotary tool should eliminate most repairs.

[formula14]

Edit, on the subject of lathe plaster. I would have loved to have had today's rotary tools. Hand saws made quite a bit of work for the plasterers that followed us. Done properly the rotary tool should eliminate most repairs.

I rewired some of my house and dealt with a lot of lathe and plaster while putting boxes in, I found that an angle grinder worked great for getting the plaster out and than I used a jigsaw to cut the lathe. The jigsaw cut fast enough that I didn't disturb the neighboring plaster or lathe.

[barry2952]

When I was rewiring lath homes there were no power tools to cut plaster. The standard tool was a coarse-tooth keyhole saw. The coarse teeth would separate the lath from the plaster making big chunks fall out. The blades would be wasted in a day.

How do you control the massive amount of dust the angle grinder would throw off? Breathing old plaster can't be great for you.

We were a non-union shop so we got to use Yankee-screwdrivers, as there were no battery-powered hand tools. That sped things up a bit, but rewiring homes was tedious work.

[formula14]

I didn't control the dust, we weren't living in the house at the time and I wore a dust mask. It was pretty nasty and I'm sure my lungs couldn't handle it without the mask.

[barry2952]

I didn't control the dust, we weren't living in the house at the time and I wore a dust mask. It was pretty nasty and I'm sure my lungs couldn't handle it without the mask.

Yeah, we couldn't do that in occupied homes. The Zip tools are pretty nice because the flutes push the plaster and wood dust into the wall cavity, not on the floor or in your face.

[Shamrock]

I like the oscillating tools cause they will cut the plaster and lathe straight one tool one pass... I don't see how a keyhole saw would work with the wood lathe behind the plaster unless you just beat the hole strip of wood off the studs and it dropped..

[alleghenyman]

I did some rewiring in my house in Crafton and had an electrician check it out and FWIW the code is pretty lax. The only thing I would add is to use GCFIs near water (sinks, tubs, etc.) and put nearby light switches on the protected side of the circuit.

I was in the middle of a lot of other remodeling work that I was doing myself so I wound up hiring an electrician who replaced the rest of it at a reasonable price. I have a low attic full of old fiberglass and vermiculite (which may have asbestos) and didn't feel like crawling around up there in the heat. The electrician who went up there was the size of a pro wrestler and banged his head a lot on roofing nails and lost his temper a few times . Glad it wasn't me.

[Jettavr666]

I did some rewiring in my house in Crafton and had an electrician check it out and FWIW the code is pretty lax. The only thing I would add is to use GCFIs near water (sinks, tubs, etc.) and put nearby light switches on the protected side of the circuit.

I was in the middle of a lot of other remodeling work that I was doing myself so I wound up hiring an electrician who replaced the rest of it at a reasonable price. I have a low attic full of old fiberglass and vermiculite (which may have asbestos) and didn't feel like crawling around up there in the heat. The electrician who went up there was the size of a pro wrestler and banged his head a lot on roofing nails and lost his temper a few times . Glad it wasn't me.

LOL I have already been up in the "attic" of my house (more like a small crawl space BC the third floor is finished) and it was terrible. Years of old dark black coal dust from pittsburghs dirty years. I ran the new wires up there when i refinished the third floor...NOT fun.

But yeah luckily the electrical code is reasonalble. I have NO idea how people do it in places like chicago where conduit it required for all electrical work.

[alleghenyman]

LOL I have already been up in the "attic" of my house (more like a small crawl space BC the third floor is finished) and it was terrible. Years of old dark black coal dust from pittsburghs dirty years. I ran the new wires up there when i refinished the third floor...NOT fun.

But yeah luckily the electrical code is reasonalble. I have NO idea how people do it in places like chicago where conduit it required for all electrical work.

Yeah, that's how it was for me too. I didn't put two and two together until I had my chimney relined and 4 5-gallon buckets of coal soot sifted into my fireplace all day. And got all over the walls, and the floors, and the moldings, and got tracked into the new white bathtub.......

[baryyknowseverything]

I rewired hundreds of HUD homes back in the '70s. I've experienced just about every type of construction known. Your home is the easiest to rewire because of the unfinished basement. The only hard part are switch legs.

All stick-built homes have a hollow space between interior walls. You just have to know where to drill to get a wire to where you want an outlet.

Envision your interior wall with a base plate made of a 2 x 4 on the flat. The studs are 16" on center so you have a space you need to hit from below that's 14 1/2" long by 3 1/2" wide. That's your target. Studs can be located by tapping on the wall or using a stud-finder. There is no need to remove the base molding. I've never had to do that. What you can remove is the shoe molding to drive long nail right below where you want an outlet or switch. It's best to pick a location where one wire will feed an outlet on either side of the wall.

Once you drive the nail most of the way in go in the basement and find the shiny nail sticking through the floor, into the basement. If you measure about 2 1/2" from that nail and drill up you will be in the hollow space of that wall. If you're unclear of the orientation of the wall above drive a nail on the other side of the wall and split the difference between them to center the drill on the space above.

I had a journeyman that I worked under that wished he had driven the second nail as he found a shiny nail, but it was the wrong one. He ended up drilling into the lowest drawer of a dresser. When he figured out what he had done he opened the bottom drawer to find a massive circle of twisted dress shirts. I had to .

Outlets on the outside walls are a little tougher to do, requiring an 18" ship auger. That's because the trusses sit on top of the concrete or block wall, meaning that the outside wall you want to get into is about 8 inches away, requiring an angled hole. In this case you want to drive a nail at the baseboard again. This will mark where the drill bit will have to start to get into the wall space above when drilled at a 45° angle to clear the foundation. You'll be drilling up through a basic floor plank of 3/4" and a 2 x 4 which is over an inch and a half on an old house. By the time you penetrate the top of the base plate the hole will be at the rear of the space.

Finding walls in the attic is easy as the trusses sit directly on the top plates, made of 2 2x4 on the flat. The lower layer is so you can build a complete wall and the second is to give it strength and to overlap onto adjacent walls to tie everything together.

Since the attic beams sit on these walls they are clearly visible under the insulation. You can locate where you want to drill down by simple measuring off know corners below. The outside walls near the eaves are often difficult to drill on low-pitched walls but can be drilled straight down with a right-angle drill and stubby ship auger with a screw feed.

Just remember to give all your wiring 2" of mechanical protection. Simple stapling at long runs and direction changes should suffice. I could draw you pictures if you need them.

Edit, on the subject of lathe plaster. I would have loved to have had today's rotary tools. Hand saws made quite a bit of work for the plasterers that followed us. Done properly the rotary tool should eliminate most repairs.

When I was rewiring lath homes there were no power tools to cut plaster. The standard tool was a coarse-tooth keyhole saw. The coarse teeth would separate the lath from the plaster making big chunks fall out. The blades would be wasted in a day.

How do you control the massive amount of dust the angle grinder would throw off? Breathing old plaster can't be great for you.

We were a non-union shop so we got to use Yankee-screwdrivers, as there were no battery-powered hand tools. That sped things up a bit, but rewiring homes was tedious work.

Yeah, we couldn't do that in occupied homes. The Zip tools are pretty nice because the flutes push the plaster and wood dust into the wall cavity, not on the floor or in your face.