best practice for installing branch circuit runs.

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  #1  
Old 09-04-04, 05:45 PM
bbixler
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best practice for installing branch circuit runs.

I have a Federal Pacific breaker panel that I am having professionally replaced with a new 200 amp panel. There are several new circuits I would like to add to the house. I would like to run the wire from the new panel location to the general location where the circuit will be used, myself. I will have the professional do the connections at both ends.

I am looking for information on the best methods of running the wire through the attic and crawl space. I would prefer to surface mount the attic runs on the roof rafters as opposed to pulling back the insulation and drilling ceiling joist. I would also perfer to attach to the bottom of the floor joist in the crawl space. I am not sure if either of these methods are acceptable.

Thanks!
 
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  #2  
Old 09-04-04, 07:33 PM
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The codes for running cable in the attic depend on whether there is an access hole, whether it has a permanently ladder or stairs, and how far the cable will be from the access hole.

Here's a way to satisfy the codes in all cases. In the attic, nail a 2x4 across the tops of the joists and staple the cable to the side of the 2x4. In the crawl space, nail a 1x2 to the underside of the joists and staple the cable to the surface of the 1x2.
 
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Old 09-04-04, 11:16 PM
bbixler
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Thank you for your response, but now I have more questions. I want to replace all the current kitchen circuits, and add two additional ones, for a total of five 110v and one 220v circuits. Of course the kitchen is located on the far side of the house from the breaker panel.

I have about 40 feet of clear access in the attic, directly into the floor joist space above the dining room, continuing on through to the ceiling of the kitchen. The floor joist run parallel with the direction I need to go, so I have a 24 foot, clear shot from the attic across the dining room to the far side of the kitchen through the floor joist of the room above.

The first question, is there any accepted method of running the cables through the floor joist space without having to pull the gypsum board down just to attach the cables to the side of the floor joist? I assume it is not good to allow the gypsum board to hold up the cables.

Since I have so many circuits going to the same place, instead of stapling the cable to the side of a 2x4 nailed flat to the top of the ceiling joist as you suggested earlier, could I do something like nailing a 1x10 vertical to the 2x4, then staple the cables to the wide side 1x10. If so, what is the minimum allowable spacing between 12-2 20-amp wire? Are there stapling requirements? Does the 220v have special requirements? Oh so many questions. Can you recommend any literature, web sites or books that would cover this kind of detail?

Thanks for all the help!

B2
 
  #4  
Old 09-05-04, 10:29 AM
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When running parallel to a joist, simply staple the cable to the side of the joist. The 2x4 or 1x2 I mentioned earlier is only when you need to cross a joist. I recommend drilling neither in an attic nor in a crawl space.

I don't understand your question about pulling down the drywall. If you're installing the cable in the attic, I fail to see why access from below would be required.

Yes, for multiple cables, you can build some sort of chase to run them through. Physical protection can be achieved in a variety of ways. You're really just trying to keep people from stepping on the cable. Staple the cables to ensure that they stay separated to avoid the heat building that comes from cables nested together. You don't need much spacing--just a little.

You need to staple at least every 4.5 feet.

220 cabling is handled the same as 110.

I recommend "Wiring Simplified", a $6 green paperback available in the electrical aisle of Home Depot. Read it cover to cover (you can skip the chapter on farm wiring if you're not on a farm).
 
  #5  
Old 09-05-04, 11:35 AM
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Support is not required for Fished Cable

Originally Posted by bbixler
Thank you for your response, but now I have more questions. I want to replace all the current kitchen circuits, and add two additional ones, for a total of five 110v and one 220v circuits. Of course the kitchen is located on the far side of the house from the breaker panel.

I have about 40 feet of clear access in the attic, directly into the floor joist space above the dining room, continuing on through to the ceiling of the kitchen. The floor joist run parallel with the direction I need to go, so I have a 24 foot, clear shot from the attic across the dining room to the far side of the kitchen through the floor joist of the room above.

The first question, is there any accepted method of running the cables through the floor joist space without having to pull the gypsum board down just to attach the cables to the side of the floor joist? I assume it is not good to allow the gypsum board to hold up the cables.
The cables that you fish into the joist channel in the dining room ceiling "through the floor joist of the room above" are not required to be supported by anything other than the ceiling finish on the bottom of the joist channel. The code recognizes that additional support is impracticable. Here is the code section from the section on nometalic sheathed cable.

"334.30 Securing and Supporting.
Nonmetallic-sheathed cable shall be secured by staples, cable ties, straps, hangers, or similar fittings designed and installed so as not to damage the cable at intervals not exceeding 1.4 m (41/2 ft) and within 300 mm (12 in.) of every cabinet, box, or fitting. Flat cables shall not be stapled on edge.
(B) Unsupported Cables. Nonmetallic-sheathed cable shall be permitted to be unsupported where the cable:
(1) Is fished between access points, where concealed in finished buildings or finished panels for prefabricated buildings and supporting is impracticable."
{Copyright 2002 the National Fire Protection Association}

Since I have so many circuits going to the same place, instead of stapling the cable to the side of a 2x4 nailed flat to the top of the ceiling joist as you suggested earlier, could I do something like nailing a 1x10 vertical to the 2x4, then staple the cables to the wide side 1x10. If so, what is the minimum allowable spacing between 12-2 20-amp wire? Are there stapling requirements? Does the 220v have special requirements? Oh so many questions. Can you recommend any literature, web sites or books that would cover this kind of detail?
If the cable is being run parallel to the joist then you can fasten a plastic Cable Stacker to the side of the joist. If you are running at right angles to the joist you are permitted to staple them to the top of the joist every four and one half feet or less with a guard strip consisting of one inch nominal lumber on each side of the set of cables. If the attic is accessible by a permanent stairway or ladder; and yes a pull down ladder or stairway does count; then the guard strips are required along the cables entire length wherever it will be within seven feet of the floor or top of the joist. In the absence of a permanent stair or ladder the guard strips are only required within six feet of the hatch or scuttle opening.

320.23 In Accessible Attics.
(A) Where Run Across the Top of Floor Joists. Where run across the top of floor joists, or within 2.1 m (7 ft) of floor or floor joists across the face of rafters or studding, in attics and roof spaces that are accessible, the cable shall be protected by substantial guard strips that are at least as high as the cable. Where this space is not accessible by permanent stairs or ladders, protection shall only be required within 1.8 m (6 ft) of the nearest edge of the scuttle hole or attic entrance. {Copyright 2002 the National Fire Protection Association}

Thanks for all the help!

B2
You're entirely welcome
--
Tom H
 
  #6  
Old 09-05-04, 11:59 AM
bbixler
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I really appreciate the time and information you have given to me. I will definitely get the book you mentioned.

I will try to clarify the part in the previous thread about pulling down drywall. I have a 40' run in the attic over the first floor bedrooms that runs perpendicular to the ceiling joist. At the end of the 40' attic space I run into the box end of floor joist for a second floor room over the dining room and kitchen. The floor joist under the second floor room, over the dining room and kitchen run parallel to where I need to go in the kitchen. If I drill a hole in the box end of the floor joist, I can look through the joist space all the way to the outside wall of the kitchen, where I ultimately am trying to get to. The second floor room above the kitchen and dining room is a vaulted ceiling to the bottom of the roof rafters, so I have to run the cable through the joist space between the upstairs room and the ceiling of the kitchen and dining room on the first floor. I have pulled out the upper kitchen cabinets and ceiling soffit from the outside wall of the kitchen where the run will terminate. If I stick my head up into the joist space where the soffit used to be, I can see all the way to the hole drilled in the box end from the attic. So I am looking for a way to permanently install the cables in this joist space without having to pull down the drywall every 4.5 feet to put in staples.

Again, thank you for your input and patience.

B2
 
  #7  
Old 09-05-04, 12:11 PM
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Okay, thanks for the clarification. As Tom said, just skip the stapling.
 
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