adding recepticles to an old brick house


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Old 07-10-06, 07:03 AM
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adding recepticles to an old brick house

Hi All,

I want to do a 20a run for 6-8 recepticles to get our living room rewired. I have only one interior wall recepticle in my plan, the rest need to go along the brick exterior wall. I'll be running the wire in our crawl space. Being that the house is old and I don't want to screw up a whole wall of plaster, what's the easy way to do this? I'm not opposed to the idea of nice flat raceway coming up from the floor (not running along the base of the wall) to a box mounted on the wall but I hate the idea of a junction box under the floor at each outlet so I can join the thhn wire for the raceway to the romex for the run. if it's only 16" of raceway (4 through the floor and 12 above) do I have to use THHN? How might I get these outlets into the wall without making an ugly mess? I'm unwilling to put a recepticle in the floor...what else might I do?
Also, when I wire under the crawl space, can I just tack the wire to the bottom of the floor joists, or does it have to go through?
 
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Old 07-10-06, 07:20 AM
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Originally Posted by newoldhouse
...but I hate the idea of a junction box under the floor at each outlet so I can join the thhn wire for the raceway to the romex for the run.
You can certainly use THHN/THWN for the entire run, but then everything must be in conduit. You can also use NM inside the conduit, since the conduit is only for protection. However, finding flat conduit that can hold two pieces of NM will be a challenge.


Originally Posted by newoldhouse
Also, when I wire under the crawl space, can I just tack the wire to the bottom of the floor joists, or does it have to go through?
You cannot staple to the bottom of the floor joists. You must either go through the joists or install a running board and staple to the running board.
 
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Old 07-10-06, 10:01 AM
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Are you saying there are no studs, just plaster on brick? If there are studs I can think of at least three ways to do this without having to repair the plaster afterward and not using surface race. Post back if there is a stud space. I'll post my ways and the experts can correct me if I'm wrong.
 
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Old 07-10-06, 12:48 PM
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I dind't think my NM could ever be in conduit? to fit it in the flat raceway it would have to come out of the romex and go up the raceway as individual conductors.

Ray, there are no studs. the house is 100 years old. the exterior wall is load-bearing brick, then there's a small void (for insulation) and then another layer of brick inside, more for insulation than structure. The plaster is directly on the brick inside the house.
 
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Old 07-10-06, 01:06 PM
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NM is allowed to be in conduit when the conduit is for protection. However, it is NOT allowed to strip the outer sheath and use the NM as if it were THHN/THWN.
 
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Old 07-10-06, 01:57 PM
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ahh...well in that case there's no way I can fit 12-2 into the raceway. that's too bad. Which do you think is more preferable, use the 12-2 romex that I have now and make a junction box in the crawl space for each outlet. Or buy a bunch of single strant THHN that I don't have and conduit that I don't have and just run conduit the whole way around? I could use pvc for ease of use under the crawl space couldn't I? I don't recall seeing anything to join flat raceway to a box, how does one make that connection?
 
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Old 07-10-06, 05:09 PM
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Originally Posted by newoldhouse
ahh...well in that case there's no way I can fit 12-2 into the raceway. that's too bad. Which do you think is more preferable, use the 12-2 romex that I have now and make a junction box in the crawl space for each outlet. Or buy a bunch of single strant THHN that I don't have and conduit that I don't have and just run conduit the whole way around? I could use pvc for ease of use under the crawl space couldn't I? I don't recall seeing anything to join flat raceway to a box, how does one make that connection?
Using PVC conduit (NOT PVC water pipe) in the crawl space would by the way I would do the job. Be sure to cement all the joints and wait a minimum of 24 hours BEFORE pulling the wires.

For the individual conductors you will need to have black, white, green and maybe red (if you plan on any three-wire circuits). If you have more than three current-carrying conductors (the ground wire doesn't count in this particular calculation) then you will need to de-rate all of the conductors. Since this will be in a crawl space you will need to use THWN rated insulation.

As for connecting "flat raceway" to a junction box...they make transition fittings for this purpose. If you plan to drill through the floor and push the "flat raceway" through to the J-box in the crawl space be sure to seal the interior of the raceway with a non-hardening sealer made for electrical purposes.
 
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Old 07-11-06, 03:11 AM
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The big box stores have a whole section of DIY flat raceways, along with connectors, outlet boxes, etc... I have seen wider ones that would fit two 12-2 NM cables, but of course they would be more conspicuous. The packaging will tell you capacities for the conduit.

If this load bearing brick is actually cinder block, you could run armored cable up the channels in the block.
 
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Old 07-15-06, 12:35 AM
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Originally Posted by racraft

You cannot staple to the bottom of the floor joists. You must either go through the joists or install a running board and staple to the running board.

Check with your inspector. That requirement, for NM cable, applies to Unfinished Basements, not crawlspaces.
 
 

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