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In-wall Speaker, Video and Audio Cable Ratings

A guide to the requirements of the National Electrical Code (NEC) for Home Theater Installations

Many people today want to create a clean cable installation for their home theater and often want to run their audio/video cables or speaker wires inside their walls or ceilings rather than running in surface-mount raceways or just dangling around in the open.

Depending on where you live, your local city, county or other jurisdiction may require conformity to electrical codes mainly because of fire protection, electrical shock and human health. Most jurisdictions which have an electrical code use the National Electrical Code, published by the National Fire Protection Association. The NEC is a large document, over six hundred pages, which details the code requirements for a huge variety of electrical installations. Most of NEC is devoted to electrical power wiring, but installations of other wiring are covered as well.

The main purpose of NEC is to prevent hazards to human health and safety from wiring, and include:

o Electrical shock,
o Tendency to start or perpetuate a fire,
o Production of toxic fumes from wiring materials when exposed to fire.

To classify the types of cables suitable for reducing these risks, the NEC provides a system of ratings of cables. An example would be CL3, or "Class 3," which many people recognize as an "in-wall" rating because of the labeling on the spools of speaker wire found at home improvement stores. But there are many more ratings, and almost all of them are "in-wall" ratings.

The type of inexpensive speaker wire or audio/video cable you find at department stores such as basic 2-wire plastic insulation copper stranded cables or wiring is typically not rated for in-wall installation and will not have a CL2 or CL3 rating specified.

In-wall cables are coated with material that emits lower amounts of toxic fumes when in contact with fire. CL2 and CL3 rated cables follow the U.S. National Electrical Code regulation under Article 725.

CL2 and CL3 - What is the difference?

CL2 rated cables (class 2 circuit wire) are designated for residential applications and are rated for up to 150 volts.

CL3 rated cables (class 3 circuit wire) are designated for commercial applications and are rated for up to 300 volts. CL3 offers more protection that CL2 rated cables. CL3 rated cables can be used in place of CL2 rated cables, but not the other way around.

Sample Cable Descriptions

o 20 AWG (wire size per the American Wire Guage. The smaller the number the bigger the wire)
o UL type CL2, CL3
o No.of cores: 7
o Insulation thickness: 0.43
o Jacket material: PVC Nominal OD. (mm): 7.6
o Jacket color: Black

(Specification): UL subject 13 type CL2, CL3 NEC articles 725-38 (b) (1) 105?C, 300, 600 Volt Conductor: Fine stranded concentric bare copper
Insulation: 105?C PVC optional PE, XLPE, PP
Jacket: Black sunlight resistant PVC
Application: For process control and instrumentation. Passes UL type CL2, CL3 vertical tray flame test.
Installed in cable trays, raceways, conduit or aerial.


Cabled conductors use stranded tinned copper wire with 0.010" wall of tough extruded poly-vinyl-chloride (PVC) insulation, rated for 300 Volt use under U.L. Style 2464. Wires are color coded using 10 standard solid colors plus white with stripes. Conductors are helically cabled and laid for optimum flexiblility, with a Mylar tape barrier wrap (or Mylar + Foil) applied between cabled wire bundle and outer jacket.

Shielded cables have an overall Aluminum-Mylar foil shielding tape helically wrapped over cable and a tinned uninsulated drain wire for shield connection.

Outer jacket is a highly flexible abrasion-resistant polyvinylchloride (PVC) thermoplastic. DUAL-RATED jacket compound meets the requirements of both U.L. Style 2464 ABM and U.L. 13 Type CL2 TRAY CABLE. Jacket is surface printed with both UL 2464 AWM and U.L. 13 Type CL2 TRAY CABLE identifiers. Jacket wall thickness is .032" nom.

Finished cables comply with applicable U.L. tests for N.E.C. Type CL2 TRAY CABLE Vertical Tray Flame Spread. All materials are flame-spread retardant and fungus resistant. DUAL-RATED for AWM use as U.L. Style 2464 300 Volt, 80?C, OR for U.L. 13 Type CL2 TRAY CABLE 105?C use.

Rated Working Voltage: 300 Volts for AWM uses. Rated Temperature: DUAL-RATED:+105?C or +80?C .
Capacitance: Nominal capacitance from a wire to all else in a cable ranges from 25 to 45 PF/FT at 1 kHz, depending on AWG and position. Insulation Leakage: 100 megohms/1000 ft. min. at 500 VDC from a conductor to all else in a cable, at 25?C,

U.L. Agency Voltage and Temperature Ratings: UL rated: +80?C AWM, 300 VOLT per UL Style 2464. UL rated +105?C CL2 TRAY CABLE per UL 13, NEC Type CL2.
Bending Characteristics: All cables are suitable for flexing to a circle diameter of 8 cable diameters from +105?C to -10?C.
Recommended flex diameter should be greater than 20 cable diameters for flexing at -20?C.
Character Impedance: RF Impedance of twisted pairs or adjacent singles is: 87 ohms in AWG 24; 80 ohms in AWG 22. Suitable for digital signals.

Plenum and Riser

These are indicated on an NEC rating by attaching a "P" or "R" to the end (e.g., CL3P is "Class 3, Plenum"). The NEC provides particular requirements for certain cable locations because of their special potential to facilitate the spread of fire or fumes.

A plenum is a compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system. The most common "plenum" space one sees in a/v installations is a dropped ceiling space in a commercial building, being used as a ventilation return. Most residences do not have any significant plenum spaces, so this is rarely a consideration in a residential installation--but on occasion it can be.

Plenum cables are required to have jackets and dielectrics which don't easily give off toxic fumes when burned--the reason being that a fire in one part of the building can, through the ventilation system, feed toxic fumes to the entire building.

One must consult the riser requirements whenever cable will penetrate from one floor of a building to another. All risers do not necessarily require riser-rated cable.

Audio Interconnects and Speaker Wires

Audio interconnect cables and speaker wires fall under NEC Article 640. Under NEC 640.21(C), these are in turn governed by Article 725, "Class 1, Class 2, and Class 3 Remote-Control, Signaling, and Power-Limited Circuits."

General installation of wiring, including installation inside of walls, is governed by 725.61(E), the principal features of which are:

* (1) CL2 and CL3 are always permitted;
* (2) CL2X ("X" is a residential suffix, signifying a lower grade than plain CL2) or CL3X may be installed in raceways;
* (3) CL2X or CL3X, if under 1/4 inch in diameter, may be installed in a 1 or 2 family residential dwelling without a raceway; if non-concealed, it may also be installed in multifamily dwellings.

So, if a cable isn't marked CL2 or CL3, is it suitable for in-wall installation?

The NEC allows cable of a higher rating to be substituted for a lower rating, and therefore, any of the following may be used: CM, CMP, CMR, CMG, CL2R, CL3R, CL2P, CL3P, PLTC. CMX also may be used where CL2X or CL3X is required.

In a plenum, 725.61(A) governs; CL2P or CL3P are required, and CMP is a permitted substitution.

If you're in a single or two-family dwelling, CL2, CL3, CL2X and CL3X may be used (and, of course, any of the substitutions listed above). In a commercial building or multifamily dwelling, any of those cables are permitted if they are installed in metal raceways or located in a fireproof shaft having firestops at each floor. In a commercial or multifamily building, without a raceway or shaft, if the vertical run of the cable penetrates more than one floor, CL2R or CL3R must be used (or any of these substitutes: CMR, CMP, CL2P, or CL3P).

NEC Article 820: Video Cables

Under Article 820, a similar set of restrictions applies to video cables.

Normal installation conditions, including in-wall (non-plenum, non-riser): CATV may be used; CATVX may be used if the building is a single or two-family dwelling or if the cable is enclosed in a raceway. For CATV or CATVX, any of the following may be substituted: CM, CMG, CMR, CMP, CATVR, CATVP. See NEC 820.53(D).

In a plenum, cable must be rated CATVP; CMP, being a higher rating, is a permitted substitution, see NEC 820.53(A).

Riser requirements are governed by NEC 820.53(B). In one or two family dwellings, CATV or CATVX may be used (or any of these higher-rated substitutions: CM, CMG, CMR, CMP, CATVR, CATVP). In a commercial building or multifamily dwelling, any of those cables are permitted if they are installed in metal raceways or located in a fireproof shaft having firestops at each floor. In a commercial or multifamily building, without a raceway or shaft, if the vertical run of the cable penetrates more than one floor, CATVR must be used (or any of these substitutes: CMR, CMP, or CATVP).

Running Signal and Power Together

There are two good reasons not to run signal-carrying cables and power lines in a conduit or other enclosure together. The first is, simply, that it's a great way to get a lot of EMI (electromagnetic interference) into your signal chain. The second is, that it's against NEC requirements. Video and audio cables may be run in raceways with one another, but NEC prohibits running video in the same "raceway, compartment, outlet box, junction box, or other enclosure[]" with power circuits, NEC 820.52(A)(1)(b), with minor exceptions, and prohibits running audio in the same "cable, cable tray, compartment, enclosure, manhole, outlet box, device box, raceway, or similar fitting" with power circuits, NEC 725.55(A), unless separated by a barrier. Coaxial cable is required to be separated by two inches from power cable, unless either it or the power cable is enclosed in a raceway or they are separated by a "continuous and firmly fixed nonconductor," NEC 820.52(A)(2).

All of the cables below are in-wall rated; the differences have only to do with plenum and riser applications: >



Permitted Uses

Plenum Cables:


All in-wall, plenum and riser applications

Communications Riser-rated Cables:


All in-wall and riser applications; not permitted in plenums.

Class 3 Riser-rated:



Class 2 Riser-rated: 1800F



Communications rated:


In-wall rated; permitted in 1-2 family residential riser applications, or in riser with raceway/fireproof shaft (see above); not permitted in plenums

Class 2 rated:



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  Running cables and wires through existing walls

Routing wires in existing walls and ceilings can prove to be very difficult particularly if the route is very long. Cutting into your wall or ceiling requires a kind of detective hunt and inspection before you can determine how you are going to feed your cables from point A to point B. You have to know what is in the way and you do not want to cut into anything and damage it, particularly power wiring or pipes. Be prepared to shut off power in the area you will cut. Always drill small "pilot holes" first and explore the area behind the wall with a bent coat hanger end and a "stud finder" that can distinguish between different types of obstacles behind your walls, including studs, AC cables, and pipes.

Speaker wire
The two main factors to consider with speaker cable are the wire gauge and the number of conductors.

The gauge of your wire should depend on how far the wire has to travel from the A/V receiver to the speaker. The lower the American Wire Gauge (AWG) number, the thicker the wire. Significant power losses can occur over long runs, resulting in lower performance.

If the distance from amplifier to speaker is less than 80 feet, use 16 AWG. If 80 to 200 feet, use 14AWG. If more than 200 feet, use 12AWG.

You can choose speaker cable with two or four conductors. Two-conductor cable is all you need to wire one speaker. Four-conductor wire is mostly used in multi-room applications with volume controls. For example, if you're going to run wire from a receiver in your living room to a pair of speakers with a volume control in your dining room, you would run four-conductor wire from the receiver to the volume control, and two-conductor wire from the volume control to each speaker.

You may see in-wall speaker cable identified in short hand that indicates its gauge and its number of conductors. For example:

* 16/2 is 16-gauge wire with 2 conductors
* 14/4 is 14-gauge wire with 4 conductors

You have two different options for terminating speaker wire: bare wire or speaker connectors.

For good connections, use speaker wire terminated with connectors instead of using stripped bare wire ends. There are a variety of speaker connectors available but the most commonly used are pin and banana connectors.

Ethernet cable (CAT-5, CAT-5e, CAT-6)

Typically used for computer networks, this family of cables is often referred to as CAT-5, but these days, you'll likely be installing CAT-5e or CAT-6. These newer cables are able to pass data at a faster rate. CAT-5e and CAT-6 products are backwards compatible with devices designed to work with CAT-5 cable.

Ethernet cables are very similar to phone sockets (those little clear plastic blocks that you plug into the broadband modem from your phone. The phone plug has a special ID code: RJ11. This defines the connection type. An ethernet plug has a similar code: RJ45. You can clearly see the difference. An ethernet plug is considerably larger, longer and has 8 gold connectors compared to the 4 of the phone plug. There are 2 types of ethernet cables: Ethernet patch cable: a straight through connection and a crossover cable.

* Cat 3 - used for 10 Mb/s speeds
* Cat 5 used for 10/100 Mb/s speeds
* Cat 5e used for 10/100/1000 Mb/s speeds
* Cat 6 used for Gigabit or 10 Gigabit Ethernet
* Cat 7 will be used for Gigabit or 10 Gigabit Ethernet

The benefits of using Ethernet cable to pass audio/video signals:

The use of Ethernet cable for whole-house audio/video systems is growing more popular. Ethernet cables stand up to interference better than speaker or audio/video cables, even the common unshielded variety, called "UTP" (unshielded twisted pair). Running long lengths of Ethernet cable can also be more cost-effective than running long lengths of audio/video cable.

Baluns (Balanced Unbalanced) These devices allow you to send regular audio/video signals to a different room via Ethernet cable.

Terminating Ethernet cables

You'll need RJ-45 connectors for the ends of the cable, and a crimp tool to secure the connection. When terminating the cables, you'll need to strip the Ethernet cable, and untwist the twisted pairs so that you can insert each conductor into the proper hole in the RJ-45 connector. You'll most likely use the common 568b configuration which places the cables in this order:

* Pin 1 white/orange wire
* Pin 2 orange wire
* Pin 3 white/green wire
* Pin 4 blue wire
* Pin 5 white/blue wire
* Pin 6 green wire
* Pin 7 white/brown wire
* Pin 8 brown wire

Audio Video Cable Connections Summary

CAT5 to HDMI Extender Set

CAT5 to HDMI Extender Set uses CAT-5E or CAT-6 cables as the transmission media. One SEND unit, one RECEIVE unit, AC adapter.

A CAT5 to HDMI Extender Set will allow you to extend your HDMI connection using CAT-5E and CAT-6 cables. Connect to different HDMI sources, such as your satellite receiver or Blu-ray DVD player without losing video resolution. The CAT- 5E and CAT-6 cables are also better to use as its twisted pair cabling provides added protection from outside interference and increases overall signal transmission distances.

The signal will be sent with perfect video quality. Use shielded CAT-5 or CAT-6 wire to get the best quality signal. Since CAT-5E and CAT-6 cables are smaller than a long HDMI cable, the cables are discreet and easy to hide in a house and behind walls. By using a CAT5 to HDMI Extender Set, you can also extend the length of your HDMI signal in an affordable way. The use of inexpensive CAT-5E and CAT-6 cables makes for an affordable solution for custom installers and home theater enthusiasts. The CAT5 to HDMI Extender Set can lengthen and boost HDMI 1080p signals up to 60 meters and HDMI 1080i signals up to 120 meters. The CAT5 to HDMI Extender Set is also capable of extending to over 200 feet with 480p and 720p signals. Moreover, the HDMI extender is backwards compatible and can be used with HDMI or DVI inputs using a $25 DVI to HDMI adapter.

CAT5 to HDMI Extender Set Features:

* Uses 2 - CAT-5E/6 cables to substitute for an HDMI cable to achieve long distance transmission.
* Follows the IEEE-568B standard
* Transmission distance reaches up to 60 meters for 1080p and 120 meters for 1080i.
* Auto-adjustment of feedback, equalization and amplification. The user does needs not to care about the length of the cable.
* Compact size.
* Signal rates up to 2.25 Gbits in support of a 1080p display.
* Each port supports HDMI or DVI (with an adapter) inputs.
* HDCP compliant.

CAT5 to HDMI Extender Set Contents:

* Send unit
* Receive unit
* 5VDC Power Supply
* Operating Instructions

CAT5 to HDMI Extender Set Installation Tips:

* Connect the HDMI input source to the SEND unit
* Connect two CAT-5E/6 cables to both the Send and Receive units
* Connect the HDMI output
* Plug the power into the Receive unit

Audio/video cables

Long runs of audio/video cable are susceptible to interference, and also tend to be relatively expensive. That's partly why Ethernet cable has become a more popular option.