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What is common practice or code when running new electrical lines in a home(15 amp/20 amp) in a basement that feed up to the 1st and 2nd floor of a home?

Is there a rule on how many wires can be run down the same floor joist overhead? In other words, If I need to run 10 new 15amp/20amp lines, can they bunched together and secured to the floor joist overhead safely, or is there a rule on how many cables can be together? And what is the rule if these wires need to cross a metal gas line?

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    You're talking about running along the face of the joist (wide part), not the edge (thin part), right? And you're going parallel, not perpendicular, correct? – Tester101 Mar 26 '16 at 19:43
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Bunching together is a serious issue. For instance, in EMT conduit, you are allowed only 9 active conductors regardless of pipe size, unless you derate (use larger wire than normal). That means four circuits, or three 3-phase circuits. I notice the multi-cable racks only hold 4 cables.

The reason is heat, and you have to design for worst case, you can't armwave it with "it's residential, they'll never all be used at capacity at once." At least it isn't for you to armwave; Code decides which corners may be cut based on a lot of research and experience. Even then, Code is a bare minimum- common sense also applies. I wish a Code expert would speak up.

  • Code allows for maximum fill in a less than 24" lengths with no derate's. It is the length and more than 3 current caring conductors. There is a specific derate based on the number of conductors that make it impractical to use larger sizes , I just found a 08 code book and 167 12 Awg are allowed in a 4" EMT conduit based on table 1 chapter 9, (Annex C table C1). I don't think these have changed much in years. – Ed Beal Mar 26 '16 at 23:16
  • wolF>you are allowed only 9 active conductors regardless of pipe size. It is not that cut & dry. It is 9 without any derating. – Pete Mar 27 '16 at 3:55
  • Actually, you can put as many wires in a conduit as you want. They just have to be derated according to Table 310.15(B)(3)(a) of the NEC. Deration begins with the 4th current-carrying conductor. – ArchonOSX Mar 27 '16 at 8:34
  • Actually, you can put as many wires in a conduit as you want. They just have to be derated according to Table 310.15(B)(3)(a) of the NEC. Deration begins with the 4th current-carrying conductor. – ArchonOSX Mar 27 '16 at 8:36
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You are allowed to put 2 lines under 1 staple. The conductors can cross the gas line or run next to it but not secured to the gas line.

I must apologize on the staples. I looked up the 3 cases I had and all 3 were rated for 2 cables and are not standard they are long leg. 99% of all the staples out there are only rated for 1 NM cable, as 12-3 & 14-3 With ground are usually round only 1 cable is allowed. Here are several examples of cables from the MFG only listing 1 cable 2-3 conductor.example 1 viking. added space to separate links example 2 gardner bender. added space to separate linksExample 3 platt search for steel staples. Almost all of these shown give their application as 2 or 3 conductor a single cable. So I was wrong a standard staple is only listed for 1 cable not 2. Any more than 3 current carrying conductors would also require a derate since the hot and neutral are both current carrying if they were attached for a length of more than 24” derating would be required.

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    Can you cite the code, or manufacturer's instructions that allow two cables per staple? – Tester101 Mar 26 '16 at 19:46
  • There is no Code for the number of cables under a staple. This would need the manufacturer's identification of the staple as suitable for two cables or you would need approval from the AHJ. – ArchonOSX Mar 27 '16 at 8:40
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In residential applications, house wire should not be running so warm that aggregating many lines together could cause a heat problem. (Commercial and industrial wiring have different rules which could result in a thermal problem.)

There is nothing about natural gas or propane lines being near electrical wiring to be concerned about. They should be independently fastened, neither depending upon the other. Properly installed gas pipes inside a home are safe. Same for electrical wires. If you are in a disaster-prone area (earthquakes, tornadoes, hurricane, etc.) there could be additional local requirements or recommendations. Perhaps extra slack in the wire or a barrier of some sort.

  • For the same reason a gass line is not allowed for the grounding electrode, my code book is at work bui I will find the reference. – Ed Beal Mar 26 '16 at 22:58
  • @EdBeal: Indeed the opposite is true. A metallic gas line should be bonded to the electrical grounding system. – wallyk Mar 27 '16 at 1:12
  • @wallyk gas lines are only bonded where they may become energized (e.g. in a furnace). If the gas line is isolated in the furnace, so that it's not likely to be energized, then it doesn't have to be bonded. – Tester101 Mar 27 '16 at 4:27
  • @Tester101: Yep, That makes sense. I have not worked with non-conductive gas lines. – wallyk Mar 27 '16 at 4:41
  • The Code allows the equipment ground for the furnace to act as the bond for the natural gas piping system. 250.104(B) The equipment grounding conductor for the circuit that is likely to energize the piping shall be permitted to serve as the bonding means. – ArchonOSX Mar 27 '16 at 12:15
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You asked several questions and you have a lot of responses here but I am hoping to more specifically answer your questions:

What is common practice or code when running new electrical lines in a home(15 amp/20 amp) in a basement that feed up to the 1st and 2nd floor of a home?

This question is quite vague and I am assuming you are using Type NM cable. The Code compliant practice is to secure them properly and install them in a "neat and workmanlike manner" according to Article 334 of the National Electrical Code. Iggy gave you the section of Article 334 regarding securing and support and some examples of NM cable staples.

Is there a rule on how many wires can be run down the same floor joist overhead? In other words, If I need to run 10 new 15amp/20amp lines, can they bunched together and secured to the floor joist overhead safely, or is there a rule on how many cables can be together?

Short answer: No there is no limit to the number of wires that can be bunched together. EXCEPT if you are passing through a partition that will be sealed or caulked the wires have to be derated (meaning they can not carry as much current).

334.80 Where more than two NM cables containing two or more current-carrying conductors are installed, without maintaining spacing between the cables, through the same opening in wood framing that is to be sealed with thermal insulation, caulk, or sealing foam, the allowable ampacity of each conductor shall be adjusted in accordance with Table 310.15(B)(3)(a) and the provisions of 310.15(A)(2), Exception, shall not apply.

Additionally the cables are normally installed through the joists when the are run perpendicular to the joists unless they larger wires.

334.15(C) In Unfinished Basements and Crawl Spaces. Where cable is run at angles with joists in unfinished basements and crawl spaces, it shall be permissible to secure cables not smaller than two 6 AWG or three 8 AWG conductors directly to the lower edges of the joists.

Lastly you asked:

And what is the rule if these wires need to cross a metal gas line?

There is no "rule" or Code prohibition. NM cable can be run with, or across, gas lines or other metal piping systems.

Good luck!

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Electrical Code

110.3.B Installation and Use. Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling. (abide by manufacturer's product intentions & directions)

334.30 Securing and Supporting. Nonmetallic-sheathed cable shall be supported and 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 outlet box, junction box, cabinet, or fitting. Flat cables shall not be stapled on edge. (don't damage the cables & keep flat cables flat when stapling)

Avoid hanging wires from or attaching to gas lines, plumbing lines & ductwork. Running over or next to them is fine & normal. Avoid the top picture below as this can splinter dimensional or standard building framing. Instead install furring strips to staple into. Keep all wires at least 1-1/2" away from framing edges. You may find the below stackers easier to use than a whole lot of staples.

wire securing

  • Iggy, you have provided listed means for more than 1 wire+ – Ed Beal Mar 26 '16 at 23:02
  • That's not really the relevant code section to answer this question. That section simply says when, and at what interval, the cable should be supported. – Tester101 Mar 27 '16 at 4:30

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