Conduits for power, IC's & more.

[nightflier]

We're going to be doing some work in a wooden cabinet this weekend to install a pretty fancy surround sound system. The cabinet is a hardwood built-in unit (attached to the wall) and we will be drilling 2" holes through each shelf for the cables. We will also be installing conduits through 9" of drywall to the amps which are stored in a seperate space underneath that has 2 cooling fans built-in.

From the looks of it, we will only be able to create two paths for the cables. My initial thought was to run power through one, and everything else (IC's, video, speakers) through the other. Is that the best solution to minimize interference? Also, how far appart should both paths be?

Also, we need to purchase 10' power cables for the amps (the 6' ones don't reach), and to keep costs down, we were going to use some kind of generic cable. The amps are two 200W stereo units and a 200W 3-channel unit (Anthem MCA's). What types of specs should we be looking for in a good quality generic power cable from a hardware store?

[E-Stat]

What types of specs should we be looking for in a good quality generic power cable from a hardware store?
Most likely, you would have no qualitative choices at all. I would make my own using Belden 83803 double shielded wire and Schurter, Wattgate, or Marinco connectors available from Parts Express.

http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=110-400&DID=7&raid=42&rak=110-400

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=100-790&raid=53&rak=100-790

rw

[nightflier]

I hadn't thought about building my own. I'll have to give that consideration. I measured the conduit out and it's about 6.5', but that would be tight, so three 8' power cords should do it.

I really was hoping to find a decent quality molded cable w/o having to go the brand-name route, though. I was told that hospital-grade would be sufficient, but I don't know what that means exactly. By the way, the conduits we drilled are 1.5' appart. We figured that would be enough to avoid any interference from the power cords.

Does anyone know if there will be interference from running audio IC's, speaker cables, and a component video cable through the same conduit?

[E-Stat]

I really was hoping to find a decent quality molded cable w/o having to go the brand-name route, though.
A very popular inexpensive shielded cord is the Volex 17604 (part of Belden). Here's a link to one source:

Volex 17604 (http://www.newark.com/NewarkWebCommerce/newark/en_US/endecaSearch/partDetail.jsp?SKU=37F3337&N=0)


I was told that hospital-grade would be sufficient, but I don't know what that means exactly.
I've only heard the term "hospital grade" in context to outlets. To prevent possible combustion in an oxygen atmosphere, the ground contacts before the other pins. While that feature is of little use in the home, they also have certifiable tension on the male plugs to provide the best contact. The suckers are really stiff.

rw

[jneutron]

I hadn't thought about building my own. I'll have to give that consideration. I measured the conduit out and it's about 6.5', but that would be tight, so three 8' power cords should do it.
Power cords are rated for use in free air. Putting them into the confines of a conduit is not within the design specs of the cords. I do not recommend it.

Cheers, John

[pelly3s]

Power cords are rated for use in free air. Putting them into the confines of a conduit is not within the design specs of the cords. I do not recommend it.

Cheers, John


that doesnt make any sense to me. considering that conduit is intended for running power cabling. most decent gear uses SJO for a power cord anyways

[Resident Loser]

that doesnt make any sense to me. considering that conduit is intended for running power cabling. most decent gear uses SJO for a power cord anyways

...power cables or power cords...two very different animals...UL and your insurance company may have an opinion that differs from yours...

jimHJJ(...quite dramatically...)

[E-Stat]

Power cords are rated for use in free air. Putting them into the confines of a conduit is not within the design specs of the cords.
The Belden 83803 is designed and rated for plenum use even though I use it in free air.

rw

[jneutron]

that doesnt make any sense to me. considering that conduit is intended for running power cabling. most decent gear uses SJO for a power cord anyways
The rating for any wire is based on the ability of the insulation to survive the heat that is generated within the wire. Most wires are rated based on the maximum temperature the wire will go to for the specified current. Insulations are temp rated, with polypropylene rated for up to 80 Centigrate, PVC up to 90-105, Kynar at 105 to 125, and FEP, Kapton, Silicon up to 200 C. (this info from manhattancdt.com/tech/carryingcapacity.htm) (got lazy, caps and www needed).

Belden, in their tech info pdf, explain the current derating needed for multiple conductors on page 16.4 of their pdf. They also specify that the ratings are based on use in still air at an ambient of 25 C. A conduit is not the same as still air. The wire temps will end up higher, and you may exceed the designed insulation temperature capability.


The Belden 83803 is designed and rated for plenum use even though I use it in free air.
A plenum is by definition, a duct which carries air, no? Plenum rated has to do with fire outgassing byproducts, not with the capacity of the wire. I believe plenum rating came about as a result of a fire which killed many Arrow company executives a while back, where the toxic fumes from insulation decomposition were carried via the HVAC ductwork the wire was pulled through, to the people who died...my memory in this regard may be suspect, of course..

Cheers, John

[Resident Loser]

The Belden 83803 is designed and rated for plenum use even though I use it in free air.

rw

...just some facts...a plenum is a plenum...it is free air in a large, but confined space i.e. the return in an AC system...not a conduit, at least in the normal, everyday, electrician's sense of the word.

According to a few sites, the cable you mention is UL listed as FPLP, CMP...simply rated for use in a plenum...and the specific applications are stipulated as: fire alarm systems(which is why it's outer jacket is red), voice communications and smoke detectors, control or instrumentation,...power cords? sorry, ain't on the list...it's neither rated nor tested for such an application.

jimHJJ(...so, you pays yer money and you takes yer chances...)

[E-Stat]

...and the specific applications are stipulated as: fire alarm systems(which is why it's outer jacket is red), voice communications and smoke detectors, control or instrumentation,...power cords? sorry, ain't on the list...it's neither rated nor tested for such an application.
That makes perfect sense for the voice communication, smoke detector, control and instrumentation apps you mention using stuff like CAT-5 cable. I guess I've just never seen 12 gauge, 20 amp, three conductor, 300 volt signal wire before!

83803 (http://www.partsexpress.com/pdf/100-790s.pdf)

There are some commercially available power cords available that use 83803.

rw

[Resident Loser]

...No one mentioned Cat-5...I'm referring to your cited part number 12/3 config and all...BTW, Cat-5 is a low voltage, data/telecom wire...nothing to do with FAs, SDs or the rest and not rated for such use...typical 22/24 ga. would not provide any safety margin for those types of circuits and the only reason it has a plenum rating at all is to lower toxicity, as JN pointed out; beyond that, keeping non-essential voice and/or data going is a non-issue.

Have you ever been in a plenum space? Have you ever seen the type of wire mandated by local ordinances for use with fire alarm systems and their sensors and the communications systems(including the main consoles and each comm station) that are an integral part of such systems(at least here in NYC that is) for the fire safety director/firefighters use? That's the stuff, it's even available in multiple- pair configuration for certain apps.

It's all red(an obvious hands-off to the wire guys), plenum rated, shielded and over-spec'd/built. Those ratings are max BTW, bad things like voltage/current surges can and do happen...add to that not every component in an FA/Comm system is "home-run", some circuits have multiple branches, so those ratings are spec'd out to a maximum load allowing for a certain wiggle room...greater distance, greater current, etc. plus that potentially inhospitable environment.

And if you'll note, the first line of your link(of which I am familiar) states in big and bold B&W:

83803 Non-Paired - Plenum-Rated Fire Alarm Cable

...not audiophile grade power cord or one of any other sort for that matter.

Insofar as the commercially available cords you speak of, are they UL rated as an entity...the wire, by itself, may be, the connectors, by themselves, may be, but as a whole, 1+1 doesn't necessarily equal 2 to Underwriters Lab.

Like the old saying goes, you can put your boots in the oven but that don't make 'em biscuits.

jimHJJ(...thanx to Renko from Hill Street Blues...)








That makes perfect sense for the voice communication, smoke detector, control and instrumentation apps you mention using stuff like CAT-5 cable. I guess I've just never seen 12 gauge, 20 amp, three conductor, 300 volt signal wire before!

83803 (http://www.partsexpress.com/pdf/100-790s.pdf)

There are some commercially available power cords available that use 83803.

rw

[E-Stat]

Have you ever seen the type of wire...
I have some of the stuff.


It's all red(an obvious hands-off to the wire guys), plenum rated, shielded and over-spec'd/built.
Exactly. Over-spec'd built. And double shielded which is why I use it for a power cord. None of my components comes close to exceeding its 300 volt / 20 amp / 200 degree C capabilities.


And if you'll note, the first line of your link(of which I am familiar) states in big and bold B&W:

83803 Non-Paired - Plenum-Rated Fire Alarm Cable

...not audiophile grade power cord or one of any other sort for that matter.
And when you visit their website and choose the pull down menu to identify the type of cable, there are 38 different choices and none of them say "power".

Compare 19364 "portable cordage" (Belden speak for power cord - also chosen by audio cable companies) to 83803. Please indicate which metric(s) render the 83803 less capable than the far cheaper 19364 for carrying 120v AC.

rw

[jneutron]

Exactly. Over-spec'd built. And double shielded which is why I use it for a power cord. None of my components comes close to exceeding its 300 volt / 20 amp / 200 degree C capabilities.


Compare 19364 "portable cordage" (Belden speak for power cord - also chosen by audio cable companies) to 83803. Please indicate which metric(s) render the 83803 less capable than the far cheaper 19364 for carrying 120v AC.

rw
Over spec'd: is the red stuff overspec'd with respect to handling? Is it's jacket structure tough with respect to abrasion resistance and flexure? I believe portable cordage is designed to withstand continued rough handling, as well as silly things like temperature and U/V exposure and chemicals and stepping on it..While, I am not sure that plenum rated fire stuff has to go through the same physical stressing..

While your components do not exceed the current draw, is the 300 volt plenum stuff capable of withstanding line transients in the 6 kV range, the flashover limit for outlets in the USA? That I would worry about.

There are too many questions when using wire not rated for the application. I do not know if merely temp or voltage or current is an accurate metric for the safety of a specific wire for use as a line cord.. I prefer safe, hence my statement on running line cords through a conduit, I do not recommend it.

Cheers, John

[Resident Loser]

...with your claims adjuster and the local FD should, God forbid, the unthinkable happen.

jimHJJ(...inner details will be of little concern...)

[E-Stat]

...with your claims adjuster and the local FD should, God forbid, the unthinkable happen.
What I find amazing is how wimpy the average lamp based power cord is found on many an audio component.

rw

[E-Stat]

While your components do not exceed the current draw, is the 300 volt plenum stuff capable of withstanding line transients in the 6 kV range, the flashover limit for outlets in the USA? That I would worry about.
Ok. What would be the criteria for said? Presumably the cheap UL listed 18 gauge lamp cord already meets that spec.

rw

[jneutron]

Ok. What would be the criteria for said? Presumably the cheap UL listed 18 gauge lamp cord already meets that spec.

rw
You answer the question within your question..UL.

It is not by chance that belden has a specific category called "portable cordage". I'm sure they know why they do not call the 83803 portable cordage..I do not.. Could be it is better in all aspects, maybe not..

Cheers, John

[jneutron]

What I find amazing is how wimpy the average lamp based power cord is found on many an audio component.

rw
I agree. They do look very wimpy. But, for the most part, they have been subjected to specific requirements, and passed them. While what you choose (generic you) to use for the app may indeed be much better, there is a distinct possibility that some spec that is unknown to you can bit ya in the hindmost. Chemical, ozone, uv, spike, compression..whatever.

That is a problem with aftermarket cords..while they may actually be better safetywise, if a fire results, the lack of that UL listing will be what the insurance guys look for. And from some of the technical white papers I've seen, many of the aftermarket guys have no clue what safety aspects to worry about..

Cheers, John

[E-Stat]

I agree. They do look very wimpy. But, for the most part, they have been subjected to specific requirements, and passed them.
Gotcha. You don't know. I'll be the first to inform everyone if any component causes the 12 gauge wire to even get warm.

BTW, I don't run anything in conduits. I just use outlets n' cords. The only thing I've seen placed in them by electricians is Romex.

rw

[bfalls]

There's another problem with running cabling in conduit, not all power cords connect on the same side of the hardware. It seems no matter how hard you try to isolate the power cords from the signal cords there's always a compromise with one or more. I've tried running the cord under the equipments case parallel to the back panel which works OK, until you factor in better quality (heavier, better shielded) cables. Using a power conditioner has it's own issues. Mounting either on the top or bottom shelf will require power cords is some proximity to the source cables. Why can't manufacturers be more consistent/standardized in their designs. I know better power cords shield EMF better, but can they eliminate it altogether?

[jneutron]

Gotcha. You don't know. I'll be the first to inform everyone if any component causes the 12 gauge wire to even get warm.
You crack me up..I have been telling you all along that I am unable to provide the necessary specifications that must be exceeded to be safe. And, I do not know if the cable you mention exceeds all the requirements that relate to safe operation.

I do know that I teach two levels of electrical safety here, and have operational requirements that normally do not exist on this planet, but I cannot specify what wire that is not rated for portable cordage will be useful or safe for such. That is why I recommend using the right material for the right job. Anything else is very possibly, a gamble. I will not gamble with safety.

I could just as easily use #2 awg as a line cord, twist 3 right up, use it..it will also, as you say, not cause the #2 to warm up....but the question would be, does the insulation stand up to transient conditions which are always on the power line??? If flashover occurs, is the insulation self extinguishing??? Recommending anything based on just the copper guage is not the solution, it can be far more complex.


BTW, I don't run anything in conduits. I just use outlets n' cords. The only thing I've seen placed in them by electricians is Romex.
rwI also do this. I will not attempt to run power through a condiut which is not designed for such. I will run cat 5, or speaker wires, or tstats, or doorbells, but for power, I also use only wire made for it..my house wiring must be foolproof, as it is my house..

And it is against code to mix power and signal in a conduit.

There is a very good reason code exists...it is to keep fools like myself from doing stupid things that appear on the surface to be better than code.

That is also the reason I do not provide design information for the line cord I made. Safety.

Cheers, John

[E-Stat]

You crack me up..
My pleasure!


...but the question would be, does the insulation stand up to transient conditions which are always on the power line??? If flashover occurs, is the insulation self extinguishing???
I may be out on a limb here, but I would like to think that wire tested to 200 degrees C specifically designed for critical fire controls that costs about five bucks a foot would be more resistant to such than a one dollar UL cord. I could be wrong.

rw

[nightflier]

There's another problem with running cabling in conduit, not all power cords connect on the same side of the hardware. It seems no matter how hard you try to isolate the power cords from the signal cords there's always a compromise with one or more. I've tried running the cord under the equipments case parallel to the back panel which works OK, until you factor in better quality (heavier, better shielded) cables. Using a power conditioner has it's own issues. Mounting either on the top or bottom shelf will require power cords is some proximity to the source cables. Why can't manufacturers be more consistent/standardized in their designs. I know better power cords shield EMF better, but can they eliminate it altogether?

I should probably clarify what we drilled. The "conduit" is actually two holes 2" in diameter through two slabs of 3/4" drywall that are 9" appart. So as far as the "free air" is concerned, the only point where the three power cords are close & tight, is at the holes (they're not really that tight, by the way). We finished the holes off on both sides with standard plastic cable hole covers (the kind used on computer tables).

That said, the chords are not powering little table lamps either, but three powerful amps. They are connected to a Monster Power Center that is then plugged into an outlet. I am still on the lookout for decent power cords, so the info on the Beldens is very useful. Right now, we have the amps connected with their stock 6' cords and I used three generic 2' computer cable extensions for the extra distance, so this is not the way I want to leave it.

Regarding EMF, I was wondering if the 18" of distance between the conduits (and from the other cables) is enough. Like someone else pointed out, given that power chords reside very close to interconnects on amps (the old Bryston amps come to mind), that should be plenty, even considering that these are three power chords instead of just one. We are also keeping the same distance betwen power & the rest of the cables in the shelves above, by the way.

[jneutron]

I may be out on a limb here, but I would like to think that wire tested to 200 degrees C specifically designed for critical fire controls that costs about five bucks a foot would be more resistant to such than a one dollar UL cord. I could be wrong.
rw
That test tells us that the wire is more capable of operation in an environment where temperatures are far too high for normal wire insulations. That is by design, the specific application warrants it.

The temperature capability of an insulation does not tell anyone:

1. How many flexures the insulation can withstand around radius of say, 6 inches. I have had to purchase wire that has been designed to withstand that type of operation, that being a motion controlled machine with a wiring harness. Operation capability of 200 C does not guarantee it will remain in excellent condition from use in a typical home environment.

2. How creep resistant is the insulation? If the cord is bent around a sharp corner, will the insulation creep over time, reducing the insulation capability? The temperature capability of the insulation does not tell us that.

3. How resistant to UV exposure is the insulation? Many of the cables I specify are black jacketed as part of the overall uv resistance scheme. The temperature capability of the insulation does not tell us that.

4. The maximum transient that can make it to the wall outlet is 6 kV. That is the flashover voltage at the outlet. Is this wire capable of surviving that transient, after it has been in an environment that has uv exposure, may be bent around a tight radius, exposed to compression, say stepped on, possibly scuffed? The temperature capability of the insulation does not tell us that.

You seem fixed on the guage and the temperature extreme the cable is designed for, but you are neglecting all the other aspects of the application. UL does not focus on temp and current capability as the only requirements, but consider the end use enviro and lifetime as well.

Cheers, John

[E-Stat]

That test tells us that the wire is more capable of operation in an environment where temperatures are far too high for normal wire insulations. That is by design, the specific application warrants it.
You know we've had this discussion before. I have no doubt there are some arcane characteristics required by your scientific applications. I don't have, for example, any dancing audio components that regularly stress my cords.

Middle of cable thread (http://forums.audioreview.com/showpost.php?p=96122&postcount=46)

If aftermarket cords are so unsafe, you'd think after more than a decade there would be at least a single report of an event caused by one. Go figure. Here are several companies (clearly known to Belden) who use or recommend the 83803 specifically as power cord.

http://www.ramelectronics.net/html/power-cord.html

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=100-790&raid=53&rak=100-790

http://www.elementcable.com/catalog/product_info.php?products_id=30&osCsid=72b0240882159e8ef9b4f1f92cf7e97a

http://www.diycable.com/main/product_info.php?cPath=21&products_id=529&Cid=7f15bd30d061e389158ef69847604dd6

http://zebracables.com/zc12.html

http://www.lavacable.com/purchase.htm

http://www.takefiveaudio.com/mall/Cables/belden_cable_83803.html

rw

[jneutron]

You know we've had this discussion before. I have no doubt there are some arcane characteristics required by your scientific applications. I don't have, for example, any dancing audio components that regularly stress my cords.There are definitely many arcane requirements in my applications. Note that I did not state that those requirements are necessary for home use.

No dancing audio components?? What, you using headphones:confused: If you do not have to tie down the components, the music is not loud enough..:p


If aftermarket cords are so unsafe, you'd think after more than a decade there would be at least a single report of an event caused by one. Go figure. Here are several companies (clearly known to Belden) who use or recommend the 83803 specifically as power cord.

http://www.ramelectronics.net/html/power-cord.html

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=100-790&raid=53&rak=100-790

http://www.elementcable.com/catalog/product_info.php?products_id=30&osCsid=72b0240882159e8ef9b4f1f92cf7e97a

http://www.diycable.com/main/product_info.php?cPath=21&products_id=529&Cid=7f15bd30d061e389158ef69847604dd6

http://zebracables.com/zc12.html

http://www.lavacable.com/purchase.htm

http://www.takefiveaudio.com/mall/Cables/belden_cable_83803.html

rwHow many of these vendors provide a UL approved cord using the wire you choose? The process of submitting a construct to the UL approval process will find any weak links in the product. If not done, the construct capability is unknown..It may be far superior, it may have a weak link, but that is unknown.

Since aftermarket cords are not a standalone item in house fire or electrocution statistics, you ask a question which is not answerable.

Hmmm...If I used a non UL approved line cord, and it caused a fire...what would I do...

1. Not disclose the fact that the non approved cord was the cause of the fire, so that I can allow my insurance company to pay out on a fire damage claim....

or

2. Tell the firemen, the insurance adjuster, post it on all the audio forums, tell the whole world that a non approved entity which I used to replace an approved one, was the cause of the fire.:confused: In this way, they can deny the claim.

Personally, if I were in the position, I would choose door number 1.

I do my best not to be in that position, which is why I recommend safety first.

Cheers, John

PS..although we have indeed had this discussion before, it is still a pleasure to have nice and reasonable dialogue with you over this.. tis a pity some forums do not allow this..

[E-Stat]

I do my best not to be in that position, which is why I recommend safety first.
Good advice, but if the dreaded contingency has never occurrred to anyone else, then the likelihood seems rather low to me. It is a far more defensible position to never drive or be a passenger in a car. What's the figure? - something like 40,000 people die every year in them. As for UL certification, how many folks in the general public:

A) Even know what that is

even if so:

B) Know whether or not each and every thing they've purchased that plugs into the wall has it?

Does my illuminated globe have UL certification?
Does the antique lighted stained glass turtle my wife inherited from her grandmother have UL certification?
Does my Coca Cola Polar Bear lava light have UL certification?

I can honestly say I don't have a clue as to the answer for any of those questions. None of them, however, uses $15.00 Hubbell, Schurter or Marinco plugs. :)


PS..although we have indeed had this discussion before, it is still a pleasure to have nice and reasonable dialogue with you over this.. tis a pity some forums do not allow this..
Indeed. This is an enjoyable hobby!

rw

[Resident Loser]

I may be out on a limb here, but I would like to think that wire tested to 200 degrees C specifically designed for critical fire controls that costs about five bucks a foot would be more resistant to such than a one dollar UL cord. I could be wrong.rw

...there's 200degC and there's 200degC...we aren't talking ovens or internally developed heat...we speak of fire, flame, crackle, crackle...smoke..I believe there is a difference.

Like drugs, brand names are more expensive. Teflon(tm)-insulated wire costs more because the raw materials cost more and the process to apply it requires the wire to be treated in some manner(read it once but can't remember)...plus, it isn't a simple dip, more of an extrusion application...that's why there are other, cheaper(read:generic), non-PTFE-based, flame retardant, plenum-grade wires now in use. Cost, as we already know, really doesn't mean much as it's all relative.

Teflon-wiring is cable...made for placement, more-or-less permanent installation...it goes in (fastened in most cases), it works and is left alone...power cords are, as you pointed out, cordage. Cords are designed to withstand constant handling, and regardless of your conscientious intent, it is made for a public who, in addition to leaving it bundled during use (a def no-no...again heat issues), generally mishandle it or give it to the kids to use as a jump-rope when not needed.

Generally, Teflon stuff (even Cat-5 plenum) is difficult to work with...couple that inherent stiffness of the dielectric with the three conductors, each which are comprised of seven strands of 20ga. tinned copper and it obviously seems most unsuitable for a power cord.
It also has a minimum bend radius of 3.25in. Bend it beyond that minimum(actually a negative maximum in my POV) too many times and the insulation will weaken and crack...been there, done that. It can actually damage other non-PTFE wiring as its hardness can abrade other insulations.

Cordage. The Belden PN 19364 is 14/3...three bare-copper conductors each comprised of forty-one strands of 30ga. Quite a bit more flexible...it's pvc insulations are thicker and the wire in toto has a larger diameter and contains a jute filler to help keep its shape, all the better to withstand a certain amount of anticipated mis-handling. A minimum bend radius isn't stated simply because it's not intended to be used as a permanent install. It's also specd @ 2000VAC for the Dielectric Withstand Voltage...the plenum stuff has no such spec.

It carries a UL designation of SJT. The entire list goes from HPN ( basically heater cordage) at the top, down to XT which is Christmas tree wiring. The SJT is in the top third and indicates that it is a Service Junior Thermoplastic. Not suitable for heaters etc. but not simple parallel service wire either. The thing is, it's listed for this use...something cobbled together from plenum cable simply isn't and in this day when folks can sue (and win) Col. Macwendybelle because they spilled coffee on themselves or some mindless dolt goes after Apple because he exposes himself to dangerous SPLs, I think accountability is the bottom line.

Me and my guys run solid-conductor plenum and non-plenum cable, CAT-type and otherwise...Most of it is terminated in modular patch bays...the patch cords we use are Ta-Da!!! Cat-5 configured, 24ga.stranded and pvc insulated...off-the-shelf, industry standard...

jimHJJ...and not a hint of Teflon...)