14 AWG speaker wire?

[daniel_leavitt2000]

Is 14AWG speaker wire just as good as other 14AWG wire for bus wiring? Looking at wire for both layout and 12v LED lighting systems.

[Philip H]

I would think so. It's usually twisted copper in semi- transparent coatings, so as long as you are really carefully about labeling I imagine you will be fine.

[John]

one side of the cable will be marked with either a white or black line ..

[peteski]

Robert Gilmore recommended the high end oxygen-free copper speaker wire for the DCC bus but I really don't see it making that much difference. Any copper wire will work just fine assuming the gauge is thick enough for the current it will handle.   Besides speaker wire you can get the landscaping lights zip-cord which is designed for 12V circuit.  It is available in 14 AWG.  I used it for wiring N-Trak modules.   You can even use individual conductors instead of a zip cord.

Another alternative is the heavy gauge zip-cord which is used by HAM operators and RC hobbyists. It comes in red/black insulation and in heavy gauges (like 12 and 14).  My friend used it as a DCC bus on his layout.

[jagged ben]

Well I tried, but I just could not find any authoritative resources on the ampacity of 'speaker wire'.

When choosing a wire for any application, you should ask three questions:
- is the voltage rating of the wire sufficient for my application?  For 12V applications, yes it is.
- is the current rating of the wire sufficient (see comment below)
- is the wire suitable for the conditions of use (e.g. in a wet location, in the sun, needs to be flexible, etc.).  For a model railroad bus-wire none of these should be a concern.

On the current rating:   The current rating of a wire is a rating for when the insulation will break down due to heating of the wire when a certain number of amps are run through it.   (You have to know the type of wire and its insulation as well as the size to know how many amps it can safely carry.)   14 awg wire of types listed in the National Electric Code has a minimum rating of 15A.    Apparently speaker wire isn't regulated with anything close to the same consistency across regions and applications.  When I Googled this I found widely divergent charts on how many amps you can push through a certain size of otherwise non-specified 'speaker wire'.  (Some charts seemed ridiculously dangerous.  Do NOT ever believe any source that says you can run 150amps on any type of 14awg wire.)       If you want to be conservative, I wouldn't assume any random speaker wire should handle much more than half the amps of the NEC requirements for 60C wire for a given size.  For DCC applications, this probably means that any 14awg wire is fine for any DCC system up to 8amps, especially since a given booster will rarely run that many amps continuously on most layouts.  There are safety factors built into all of this, so that's pretty conservative.

Which is all a longwinded way of saying...
You will be fine.   

One final comment:  If you've already got this speaker wire, have at it.  If you are considering buying, make sure you are not paying extra for some 'high quality' wire for audiophiles.  Compare to the price of ordinary 14awg THHN at your nearest big box store.

[peteski]

On the current rating:   The current rating of a wire is a rating for when the insulation will break down due to heating of the wire when a certain number of amps are run through it.   (You have to know the type of wire and its insulation as well as the size to know how many amps it can safely carry.)   14 awg wire of types listed in the National Electric Code has a minimum rating of 15A.    Apparently speaker wire isn't regulated with anything close to the same consistency across regions and applications.  When I Googled this I found widely divergent charts on how many amps you can push through a certain size of otherwise non-specified 'speaker wire'.  (Some charts seemed ridiculously dangerous.  Do NOT ever believe any source that says you can run 150amps on any type of 14awg wire.)       

Wire gauge is the same no matter what type of wire it is (speaker, or Romex).  You are correct that the heating of the wire and how heat resistant the insulation is makes a difference in its current rating.  The ambient temperature also plays a factor.  I look up the spec on http://www.engineeringtoolbox.com/wire-gauges-d_419.html

As far as 150A going though 14 AWG wire goes, it could be done if the length of  wire was very short.  Not practical but possible.

[central.vermont]

Using it as a bus wire could be more difficult to use. I prefer a solid wire and a wire that is not paired up with another. Reason being is that it is easier to strip the wire and solder a feeder to it.

Jon