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Rewiring the 2nd story of our new (old 1920's) house -could use input

Rewiring the 2nd story of our new (old 1920's) house -could use input


  #1  
Old 11-19-15, 10:28 AM
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Rewiring the 2nd story of our new (old 1920's) house -could use input

Hello,
We just bought a home - a 1920's 4 bedroom, two-story house with basement and unfinished attic. The main floor and upstairs are knob & tube wiring. I would like to work on rewiring the upstairs first - which is three small kids bedrooms and a full bathroom on the end of a hallway. The bedrooms have no overhead light, and the only receptacle in each bedroom is built into the wall sconce which has switch for the light - all located away from the doorway...oh, and all plaster walls!!

Here's my plan I've been dreaming about: The breaker box is in the basement. I think I have a strategy of running cable up to the attic through interior walls and then back down to the bedrooms and bathroom. I was thinking of doing the three bedrooms receptacles and lighting on a 20amp circuit, a 20amp circuit dedicated to the bathroom receptacle and light, and a 14/3 dedicated to interconnected smoke detectors (dedicated required by code, IC HW smoke detectors desired by the better half). So about 15 receptacles and 3 overhead light fixtures for the bedroom circuit. Is that overloading it, or should I pull a second 20 amp bedroom circuit and split the bedrooms?

The hallway I was going to do on a main floor circuit, since I would like to have a 3 way switch for the light over the hallway/stairs (only switch is upstairs right now). My thought was that this would allow for some lighting if the one bedroom circuit should trip.

An idea came to mind on how to deal with cutting in all these receptacles - would it work to put an abrasive wheel on a skilsaw, and cut a 8 inch wide track out of the plaster all the way around the room, install electrical boxes and wire, and then patch the track with drywall and mud? Assuming I can manage the dust?

What do you guys think? I appreciate all questions and input!
 
  #2  
Old 11-19-15, 10:40 AM
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Unless you use EMT buried in the plaster I'm not sure your method would be code. Wait for the pros to weigh in. What about fishing down from the attic for each cable then a second cable back up? More cable but better protection for the cable. You might also consider removing the base boards and running behind them or just use surface race and surface mounted boxes once painted the same color as the wall and hidden mostly by furniture they should blend in.
 
  #3  
Old 11-19-15, 11:01 AM
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I would do anything I could to fish the walls from above or below prior to removing that much plaster. In the spots where you do have to remove plaster, remove a 12x12 square and get as far as you can with a long flexible drill bit before cutting another hole.

The number of circuits sounds appropriate unless you intend to use window AC units or space heaters. In that case add another 20A circuit for the receptacles.

Code requires a switch at top and bottom of a stairwell, so that part of your plan should be upgraded from a "nice" to a "required" elements. Also consult your local building and fire code; one of those hardwired smokes may be required to be a combo smoke/CO detector (wiring is the same either way).
 
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Old 11-19-15, 12:36 PM
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ray2047 - I meant to say cut a 8in tall section out of the plaster/lath the length of the wall, where I could then drill studs as proper and nail electrical boxes. Afterwards, then replace with drywall as thick as the plaster, and mud and feather the edges. From what I've read, it's easier (or no less of a pain) to patch a large hole than a small hole. I figured then I could make the drilling and bends at the corners easier.

Or just use three junction boxes - on for each bedroom above in the attic and drop a cable down each wall where a receptacle needs to go?

I'd rather not surface mount, and I'm not sure if the baseboards could handle being pulled.


ipbooks - house does have central ac and forced air furnace, so no plans for window ac and space heaters; however, only been in the house for a month and haven't really experienced how the house does in MN winters yet. Maybe a 2nd 20amp might be good.

And you are right - MN would require smokes in bedrooms and combo smoke/CO in hallways in close proximity to bedrooms.

As far as code goes - no permit is required in my town for electrical work per the city hall clerk, so I don't really have an inspector to answer to. However, I will still follow current code, except maybe I might hold off on AFCI breakers throughout the house due to expense...
 
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Old 11-19-15, 01:18 PM
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Lighting only needs a 15 amp. circuit, plus the wire is a whole lot cheaper.
Has the main panel and incoming wiring been up graded?
Hope plan does not involve attaching any of that new wiring to the old knob and tube, you can not add onto ungrounded circuits.
A new sub panel on the second floor would make it easier to run the wiring.
Around here the panel can not be in a closet, bedroom, bathroom.
 
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Old 11-19-15, 01:38 PM
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The panel was upgraded from screw in fuses to breakers as a pre-condition of our purchase. Service was unchanged - still 100 amp service.

Plan would be two or three 12/2 homeruns to panel (one bathroom, one or two for the bedrooms), and 14/3 for smoke/CO detectors.

I had considered running a separate circuit for lighting, but I didn't think it was cheaper as a whole. 250ft of 12/2 is $50, while 14/2 is $33. If each of the three bedroom lights take two bulbs, the current draw seemed insignificant - especially if using CFLs or LED. The only benefit that I see would be to have lighting in case a breaker blew, but then again the bathroom light would be on a circuit to turn on, along with the hallway light (fed from main floor).

My GF's father suggested a subpanel, but how many circuits would I need to run to get a cost/benefit? The smoke detector would still have to be a separate run if I wanted to remain interconnected with the bedroom on the main floor, and I also thought a smoke/CO detector interconnected in the basement wouldn't be a bad thing either.

What do you think?
 
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Old 11-19-15, 02:15 PM
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A subpanel usually doesn't break even until ~6 circuit or so. The recommendation for #14 on the lighting circuit is good, mostly because it's a PITA to work with #12 wire in ganged 3way switch boxes. In terms of load it's not really a consideration either way unless you've got a ton of lights.
 
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Old 11-19-15, 03:21 PM
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I would think it would be easy enough to pull the 2 or 3 cables needed up from the basement and skip the subpanel.

I would look,at fishing the walls instead of tearing out plaster. Plaster is rarely the same thickness as drywall and tearing it out makes a mess. Depending on the type of lath is going to make a difference.
 
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Old 11-19-15, 05:13 PM
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In the old days receptacles spidered out from the ceiling fixture. Doing it that way you would only need to fish one cable to each receptacle. I'd update it though and use a 4x4x2-1/8 box with round plaster ring for the ceiling box. Not usual but just a way to consider if you don't plan on ceiling fans.
 
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Old 11-20-15, 02:08 PM
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I like the "spider" idea. I had considered ceiling boxes that could hold a fan - more or less a few bucks more for the possibility down the road...

I was considering raising the junction boxes off the attic floor, cause down the road I'd like to blow in some insulation. Currently there's only about 6in up there now - not nearly enough for Minnesota in my book!

How would you go about cutting holes in the plaster for the boxes? (wood lath) I was considering a carbide grout bit for the oscillating tool for the plaster, and wood saw blade for the lath?
 
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Old 11-20-15, 07:28 PM
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I have used a carbide Roto-zip bit followed by the woodcutting bit for the lath.
 
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Old 11-20-15, 07:36 PM
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I had considered ceiling boxes that could hold a fan - more or less a few bucks more for the possibility down the road...
You won't find a 4x4 box for ceiling fans and probably a ceiling fan box won't have the room but an accessible box in the attic as you suggested would be good.
 
 

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