Strategy for rewiring old house


Old 03-15-18, 06:18 PM
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Strategy for rewiring old house

I am in the process of rewiring a home that was built in 1927. It has a lot of knob and tube wiring and plaster walls. Perfect situation, right? Anyway, for wiring the second floor, I plan to run wire from the basement up to the attic, and then drop wires down inside the walls where I need them. Since the walls are not opened up (and I would like to avoid opening them up), I cannot run a wire down to, say, an outlet, then run the wiring horizontally through the studs to the next outlet, etc., in order to wire an entire room. My first idea was to use junction boxes in the attic at each drop point: one wire coming in, one going down to the outlet, and one going to the next junction box. However, since I also plan on putting new insulation up there and adding plywood so I can use my attic for storage, this will not work since the junction boxes will then become inaccessible. To avoid using junction boxes, the only thing I can think of is running two wires down to an outlet: one to power the outlet, and one that comes back up and goes over and down the next drop point. This seems definitely doable, but will also amount to more work and a lot more wire being used. I also have read about possible voltage drops when lines are too long.

Does anyone have any feedback? I have read many many blogs, informational websites, and even a book (Wiring Simplified by Hartwell, Schwan, and Richter) and I have gotten many tips, but nothing that describes an overall strategy like I have described.

Thank you!
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Old 03-15-18, 06:36 PM
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Are there absolutely no plans to open the walls ? That sure makes everything much easier.
If you wire with the walls closed.... set the junction boxes away from the center of the attic and don't cover them with flooring.
Old 03-15-18, 07:15 PM
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Attach the junctions above the top-level so they remain accessible.
Old 03-16-18, 04:41 AM
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Do you mean rafters? Is that allowed? I was just curious.
Old 03-16-18, 04:49 AM
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Hi, is it possible that there was strapping installed to support the ceiling, if so there would be room to fish the new cable through there, I know this is probably a long shot but thought I would mention it..
Old 03-16-18, 09:08 AM
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There's no issue with dropping two cables down the wall and going outlet to outlet, pretty much avoiding the use of junction boxes. Or you can position the junction boxes where they will continue to be accessible as others have mentioned - really, whatever is easiest.

A few notes to remember though
* You need to add enough receptacles to comply with current codes (6' away from doors, every 12' after).
* Your new circuits most likely need to be AFCI protected
* Don't forget about a new 20A circuit to the bathroom

The hardest part will be figuring out how to abandon your old K&T. One K&T circuit will probably run the receptacles and lights on the second floor, and possibly some others scattered around. It requires some planning to do it in stages (or all at once if you can). But will be well worthwhile!
Old 03-18-18, 04:59 AM
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I did a similar re wire on a 1932, two story home. The first floor was easy, i just went up from the basement for each box and ran a second wire down and over to the next box. The first thing i did was unplug all the old circuits at the main basement box so I didnt have to worry about any Knob and tube being active. The second floor was more tricky. Coming down from the attic is brutal because the walls have a horizontal stud half way down. I just dropped down one wire (opening the wall up half way down to get through the stud) and then i went horizontally around the room to each box. I had to open up a lot of plaster on the second floor to go horizontal. I just covered it with drywall after. I would avoid using junction boxes in the attic for each box. This is just more space for problems and connection issues. I would also not cover them with plywood.
Old 03-18-18, 09:50 AM
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Why not put them along the baseboard?

I'm in a 1700s stone farmhouse that has been wired and re-wired and re-re-wired, that's where both the 1st and 2nd floor outlets are.

Initial 1920-30s wiring for most homes was for "lighting" whic means 1 ceiling light in each room.
2nd floor was usually wired through the unfinished attic.

In the 1950s seems that outlets became popular, that was usually accomplished by runnng from basement to 2nd floor, going through the 1st floor by chiseling a channel into exterior masonry, then replastering, or by "bumping out" a small corner, e.g. adding a quarter round "column" in the corner of a formal room.
Outlets for 2nd floor are usually in the baseboard, often with the wiring from room to room being hidden behind crown molding downstairs, sometimes they boxed out the perimeter of 1st floor rooms to create a sort of cofferred ceiling and space to run wires.
Old 03-18-18, 02:49 PM
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Those thin white conduits are good for baseboard too, you have to have the outlets mouted externally though. This is definitely easier, but doesnt look as good as outlets mounted flush in the wall.
Old 03-19-18, 06:41 PM
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Thanks for all the responses. I really want to avoid having to open up the walls if I don't have to. For one thing, I don't think I can do all the patching and make it look like it wasn't patched. I don't know how I can get by with all the junction boxes in the attic as I will need to insulate the entire floor. That just leaves the rafters, and as someone asked, is that allowed? I guess since there's no red flags about running two wires to each outlet, I'll give that a try, at least for the first room.

Zorfdt - I've been reading up on a lot of the electric codes, but I'm not sure what you meant by "6' away from doors". Are you saying there can be no outlets within 6 feet of a door, or an outlet MUST be within 6 feet of a door? And I have disconnected all of the knob and tube. It's been off since right after I bought the house. There were two circuits and they handled all the second floor electric and all overheard lighting in the rest of the house. So I'm used to not having much electric around the house.
Old 03-20-18, 09:23 AM
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It's commonly called the 6/12 rule for spacing of receptacles in all living areas (bedrooms, living room, den, etc) It applies to new residential construction and rewiring. It does not apply to kitchens or bathrooms where there are other spacing requirements, nor does it apply to storage and utility areas where receptacles may or may not be required depending on some specifics.
  • There must be a receptacle within 6' of every break in the wall such as a doorway or archway
  • There must be no more than 12' spacing between receptacles thereafter
  • The measurement is taken along the base of the wall and continues around corners
  • Every wall segment 24" or greater in width requires at least one receptacle.
  • Hallways do not follow this rule, but if 10' or greater in length require at least one receptacle
Old 03-20-18, 02:48 PM
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I rewired my 1st house, it was an 80 year old house in a historical district in Michigan. Search / look back at old posts by me for suggestions & tips, I made several of them on that rewire. It was 25 years and two houses ago that I did it.

I did the up & down thru the same wall cavity as you mentioned. Its not that difficult & so what you use a little more cable for those 2nd story outlets. Figure 6-7' extra per outlet, 15 outlets is around 100' extra cable, That might be $35 - $45 extra in cable, not really a big expense taking in the big picture. Sometimes the big problem is getting a clear drop from the attic to the basement.

Buy extra cable in at least 250' packs. Its cheaper that way and you will use more than you think.
Try to get most of your outlets on interior walls. Normally there is no insulation or horizontal blocks to deal with.
Go ahead & buy the right tools to do the job, drill, drill bits, fish tape, wire strippers / cutter, work lights.

A trick for locating where to drill holes from the attic, While in the room & in front of the cavity area you wish to have an outlet, go straight up above that area and drill a small hole straight up into the attic about 1" or so away from the wall. Hole size only needs to be big enough to push a wire coat hanger (piece of stripped wire) thru. Now up in the attic, find the coat hanger, measure a couple inches over so you are above the top stud of the wall & within the cavity space, drill your hole that the new cable is going to go up & down. the small hole can easily be plugged with a dab of spackling & paint touch-up.

For the main panel, unless you have experience with it, I suggest you get an experienced person or electrician to do it. I was lucky & had a electrician friend that did it while I assisted him. I learned a lot with his help.

Finally, get to doing this while the weather is cooler. The attic is no place to be in the summer time heat. Good Luck Mike
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