Wire - Stranded vs. Non-

[MikeH]

Hello everyone,

I will admit up front that I electronics is not my forte. I am taking Sean's suggestion from a thread earlier this year and have checked out several books on basic electricity and electronics.    Now to my question:

In another post there is a statement that stranded wire is not required but is better. I have always thought that solid wire would be better. For the same gauge wire, the wires are thinner as the resistance drops on one single wire vs. stranded wire. Granted, it is also probably stiffer, but if given the choice, I would want to opt for the less-resistant wire. Because it has less flexibility, there would also be less chance of the wire kinking up. Also, much harder to break a thicker wire than several little ones wrapped around each other. Is my thinking wrong on this? What are the rules, either written (i.e. code) or unwritten on wire selection.

Thanks for the continuing education.

Mike

[RJ]

Mike -

This topic has been beaten to death over and over and over again on this and the other major busnut bulletin board BNO.  (www.busnut.com)

Use the search function on both BBS's to see what's been said before.

It's an on-going debate!

FWIW & HTH. . .

[robertglines1]

 Let the experts determine! biggest thing to keep in mind is anchor which ever and protect from sharp edges(rubber bushing going thru  holes drilled for passage from one area to another).Movement and rubbing is the enemy with either.  Bob

[rv_safetyman]

Oh No.  Here we go again.  I should not have even mentioned it.  However, it probably needs to be discussed again.  I don't have the time right now to search out all the other threads, but there are a ton of them.

The big controversy is the "CODE".  Others will discuss that.  But my understanding is that the approved code is the same NEC or NFPA code as your house (thin ice here).  There is a specific NFPA code for RVs (1192?)    Here is a thread on that part of the subject:

http://www.busconversions.com/bbs/index.php?topic=13369.0

There are a few diverse thoughts on the subject.  I think everyone agrees that THHN is acceptable and meets code (when installed properly).  THHN comes in both solid and stranded.

As far as current carrying capability that is a matter of sizing the wire appropriately.  As I understand the theory, stranded wire carries a bit more current, but not significant.

Then the issue of wire fatigue comes up.  Stranded wire is probably better in that respect, but lots of RV vehicles have solid wire and have for many decades.  Properly installed, fatigue should not be a problem.

Next is the issue of securing (terminating) the wire to things like outlets.  The typical outlet is designed to be used with solid wire.  Lots of discussion that stranded wire is more difficult to get a good connection (that lasts).  I used stranded wire and then secured with crimped connectors.

Then the real discussion starts when (shudder ) folks start discussing marine cable.  This cable is approved by the Coast Guard, but does not meet the applicable code for house or RVs.  Not because it is inferior, just because the manufacturers have not spent the funds to seek approval.

OK, that all sounds like I know what I am talking about.  Not the case.  I have mixed my thoughts with what I recall from previous threads.  I am posting it here to get the issues mentioned and then let the folks who really know clean up my mess .

I think Sean is pretty busy right now, but if/when he responds, take his comment as being expert.

Jim

[kyle4501]

Are you building it like a house, or like a vehicle?
Most houses use solid wire.
ALL cars use stranded wire.

Stranded wire is easier to work with in some installations, where sometimes, solid wire is easier.

For me, I'm hoping to be able to run all my wire in conduit to increase the protection from damage.

My bus has 4 skylights that will leak sooner or later, so I'm probably going to use stranded marine wire with the proper end terminals. 

[John316]

LOL, I saw that comment, and wondered if this would come up again.

We used stranded. So far so good .

God bless,

John

[luvrbus]

I used marine stranded some say it is not approved but it was my bus and I used it never was a problem and millions of RV"s on the road with romex solid wiring for the ac side in no conduit doesn't mean it is right but that the way the manufactures do it 



good luck

[47FLXclipper]

having training in both electronics and commercial electrical, I use solid ["single core"] for AC according to building electrical codes [proper terminations and strain relief] and stranded for DC [the more strands the greater the flexibility] - tinning the exposed copper ends of stranded wires will reduce connection problems from oxidation, and always better to solder connectors [preferably copper] than just crimp them - any wiring, in dedicated wireways or not, needs proper mechanical protection against penetration or abrasion - pretty much common sense

Bill

[bevans6]

I use stranded wire  for DC low voltage circuits and Romex for 120 VAC circuits.  All of the termination equipment is designed for solid wire and if it's well supported there is no realistic vibration issue.  Plus it meets code and insurance requirements and all of the RIVA units are made that way.

Brian

[kyle4501]

I'm too lazy to look for it, but I have read a very well presented explanation of why soldering connections is a bad thing - the solder wicks back up the wire & makes it stiff, then it sees more flexing at the end of the solder & leads to fatigue failures. The article talked about the proper crimp will cold fuse the connector to the wire & not have that problem.

Seems there are pros & cons no matter which way you go. 

Of all the wiring jobs I have seen, it is the installer, not the materials, that makes the difference between a good (safe) or a bad (fire hazard) install.

What ever your wire choice is, if you:
1- use the correct wire size for the circut breaker
2- use proper end connections for the wire & devices used
3- use the correct wire insulation type for the environment
4- use the correct supports
You should enjoy success.

[Jriddle]

I too read the subject line and said oh no. Might as well bring up the other dreaded topics.

LOL
John

[bevans6]

The guys who build  the wiring harnesses for high-buck race cars - the Grand-am prototypes, the Le Mans LMP cars, the Indy cars - use crimped connectors exclusively.  The harnesses these days are high frequency data busses, and some low voltage stuff like lights, motors etc.  Crimped gold plated connectors, no solder in sight.  It's been years since I researched the physics of it, but I recall something like gas-tight joints  and micro-cold-welding so that no corrosion could occur and such like.  Proper strain relief is important.

regardless, if you do a good job of any technique it will probably be fine.  At the end of the day, it's a bus, not a space rocket.

Brian

[Kenny]

If I remember correctly, my MCI9 uses tin covered stranded wire in the original wiring.

[boogiethecat]

I've posted this quite a few times... it tells the story clearly.
I set up my vertical mill with a chuck that goes up and down- it holds one end of a wire in the chuck and the other in a vise... then I bent various kinds of wires an equal distance and counted the times I bent them until they failed.
Enjoy again... and use STRANDED if you can. The finer the better...

Oh, and since someone brought up crimps, here's a long photoessay on my OPINION of how to do a proper crimp...

http://www.heartmagic.com/crimps.html

[jjrbus]

Most talk about "the code" and Da book" Has anyone actually had their bus inspected? How do you get an RV electrical inspection? Nobody is going to pass or fail your job so you can do anything you want?

The one sure way to get an inspection is have an electrical fire, that injures someone or you try put in a claim for. The insurance company or plaintiffs will be happy to provide the finest inspectors in the country to give your bus a thorough inspection to make sure it was done by Da book!
                                                                                                                    JIm