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I wonder if there is a study on lives lost from installing simple CHEAPO single strand copper wire in a moving vehicle?

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The mobile home we had bought was made in 1989; it had PEX stamped on the damned stuff, and was indeed PEX material.

The product wasn't faulty btw, it was just the PEX connectors. They cracked and spilt over time. The PEX recall paid for the replacements of those said fittings, and that PEX tubing still resides in most all of the pre-2000 era trailer/mobile home/manufactured home in the country.

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I have that same cord - Oil resistant P-123 MESA, 10/4, Type SO - running from the genny to the power distribution box in the bus. ... it is temporary and only used when the genny is running, and requires flexibility as the genny moves. Does that sound like a good fit for the cord?

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(E) Supply Conductors. The supply conductors from the engine generator to the first termination on the vehicle shall be of the stranded type and be installed in listed flexible conduit or listed liquidtight flexible conduit.

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Is there a stranded wire that meets code other then individual wires in conduit and do you have to use thhn or can you use tw

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(B) Materials and Equipment. Electrical materials, devices, appliances, fittings, and other equipment installed in, intended for use in, or attached to the recreational vehicle shall be listed. All products shall be used only in the manner in which they have been tested and found suitable for the intended use.

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Both our commercially built motorhomes had the genset wired to both the electrical panel (and a receptacle with outside access), using romex (wow? what? wtf?).

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Is that you have repeatedly said, (in more posts than I can count), that you do not want some non-compliant failure of humanity parking next to you in a campground;

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This is a free country. Do what you want.

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Recently, a participant on the Bus Conversions on-line Bulletin Board observed that respected engineers in the bus conversion community sometimes appear to offer contradictory advice on wiring methods. Specifically, he noted, one author recommended "Romex®" (a brand of what is generically known as non-metallic jacketed, or "Type NM" cable) and cautioned that "Boat Cable" was unacceptable, while a different author advised that Boat Cable was preferable and recommended against using Type NM. Furthermore, this individual had heard through other sources that using heavy-gauge extension cords would be better still (although I am certain that this advice came from neither of these authors). The poster of this observation summed it up well: "Now I am Really confused."

I tend to stay out of these debates -- it's like debating religion, or maybe politics. However, this particular contradiction appears to be a source of much anguish among first-time converters, and more light can be shed on this issue. As is often the case with religious debates, I don't expect to convert anyone's long-held beliefs. But if you are genuinely confused about this, you're not alone.

Before one can say definitively that one of these methods is better than the other (or that one is correct and the other incorrect), one needs to first understand that there are several discreet issues involved here -- codes, laws, liability, and safety -- that are over and above the simple issues of "will it work?" and "how reliable is it?". The issues are all inter-related, but they are different and separate. Problems ensue when we try to wrap them all together into one all-encompassing "right answer." I'm going to separate them out individually, while pointing out how they connect.

1. Code

There is, indeed, a set of codes and standards which cover the design and construction of "motor homes," "motor coaches," "housecars" and whatever other terms may be used from state to state to describe motor vehicles used as living accommodations. Many of the standards are applicable to motor vehicles in general, such as Federal Motor Vehicle Safety Standard (FMVSS) 108, which describes required safety equipment for all motor vehicles, and includes such items as clearance, marker, and ID lighting, safety belts, and the like. Not the subject of this article, of course, but some of us make changes to these things and need to be aware of and follow this standard.

The first standard that is most relevant to this discussion is issued jointly by the American National Standards Institute (ANSI) as ANSI A119.2 and the National Fire Protection Association (NFPA) as NFPA 1192. Much of the work behind these standards was originated by the RV industry itself, in an era when self-policing was the norm (which is a whole separate discussion) and was developed in committee by the RV industry's own trade association, the Recreational Vehicle Industry Association (RVIA). Consequently, many people still refer to this code as "the RVIA code." (RVIA requires its member companies to follow 1192 explicitly.) Nevertheless, NFPA and ANSI have done substantial additional work, and this document can now be considered a bona-fide safety code (notwithstanding claims you may have heard that it is some kind of self-serving industry propaganda).

Whether or not there is a legal requirement to comply with 1192 is a separate discussion, see below. However, it is a good idea whether or not there is a pre-existing legal requirement (also see below). In any case, if one is going to follow this standard, then the National Electric Code (NEC), also produced by the NFPA, is included by reference. In other words, a motor coach does not comply with NFPA 1192 / ANSI A 119.2 unless it also complies with all provisions of the current NEC in force at the time of conversion. At this writing, the 2002 edition is the most current version of the NEC (they are revised every three years).

Legally speaking, compliance with the NEC may be required even where compliance with 1192 is not -- again, see below.

2. Legal

First, I am not an attorney, and I suggest you seek competent legal advice for your own situation. I have had some experience, though, on both civil matters (lawsuits) and code-compliance matters in several states in the course of my career managing fleets of vehicles and designing, building, and managing high-tech facilities.

All of the matters relating to legality of both the vehicular and conversion aspects of our bus conversions are largely matters of state, not federal, law. Many people are confused or misled on this issue. Some of the confusion comes from the fact that vehicles used in interstate commerce are subject to federal regulation in preference to state regulation, a matter dictated by the US constitution. However, this is limited to commercial vehicles, by definition. While some readers may, in fact, be creating conversions for commercial use (for example, building an "entertainer" coach, such as the MaddenCruiser, to be operated by a certificated interstate carrier to transport passengers), most of us are not, and will title our coaches as "motorhomes," which are mostly subject to state, rather than federal, regulation.

In practice, many motor vehicle laws are similar from state to state (further confusing people as to the responsible authority), because adherence to FMVSS 108 is enforced on the states by the federal government, in an interesting end-run around the constitution, through the threat of withholding federal highways funds. (Want an interstate in your state? Then adopt FMVSS 108.)

The same is not true for conversion-related standards. Some states have, indeed, adopted NFPA 1192 as law. All 50 states have adopted the NEC as law. Note that the NFPA and ANSI are non-profit standards bodies, and have no force of law themselves, but when their codes become "adopted" by governmental bodies, then they become part of the law in those jurisdictions.

Now, in practice, NFPA 1192 has been adopted as law in many states, but often only as pertains to "manufacturers" of recreational vehicles. Whether or not you, as a private individual converting a bus, are considered to be a "manufacturer" and thus subject to the law varies from state to state. If you have concerns about this, you should seek the advice of an attorney licensed to practice in your state (or the state in which you will register the vehicle).

The NEC is another matter. In most, if not all, states, the NEC is enforceable against everyone, including private individuals. That's not to say enforcement is actually done -- a quick walk through almost anyone's privately owned and maintained home in almost any state will turn up at least two or three code violations. Most jurisdictions have code enforcement agencies nominally responsible for enforcement action with respect, at least, to fixed buildings. Almost no jurisdiction, though, has any formal mechanism or agency to enforce the code with respect to converted vehicles. Lamentable (in my opinion), but true.

Sadly, the legal consequences of willfully violating the code are often only evident after a tragedy, which is a nice segue to...

3. Liability

This is a thorny and often hotly contested issue. That's why the world is full of tort attorneys. States have wildly different standards, practices, and case law on this. It is flatly impossible to say universally what one's liability will be for either unsafe practices or for code violations. (Just remember, though, that here in the good old USA, anyone can sue anyone for anything.)

Many jurisdictions will find criminal wrongdoing in cases where codes have been willfully violated and injury or death results. This is in addition to any civil liability that may attach.

As for insurance matters, only your individual insurance company can tell you what its policy is on its liability for claims in the case where codes have been violated. I know that my own policy specifically excludes coverage for any act of mine in knowing and deliberate violation of the law. A sharp attorney could use that to exclude coverage, for example, for a fire caused by faulty wiring that was installed in violation of code. Remember that the NEC is law in all 50 states.

4. Safety

What all these codes and laws come down to is: safety. Almost every provision of the NEC is a direct response to some number of deaths or serious injuries. (That being said, the code can not and does not foresee and address every conceivable circumstance and every possible problem.) In many cases, provisions of code are in place precisely because common sense, conventional wisdom, and peoples' well-intentioned "good practices" would result in something being done in a way that is dangerous but completely hidden and non-obvious to even an expert eye.

The point I am making here about safety is: don't second-guess the codes. The reason for any particular code provision may not be obvious, and you may think you know a "better way," but there is probably a good reason behind it somewhere (and maybe even a few dozen graves).

Now that we've covered the background, we can discuss the debate about NM versus Boat Cable.

Type NM cable (often known by the brand name Romex®) is explicitly permitted by the NEC for use in RVs, and is safe to use for most applications. The conductors of most commercially sold NM cable (up to about 10 AWG) are solid. Many people abhor solid wire, for a variety of reasons -- its stiffness makes it hard to install in some places, nicks in the conductors can induce premature failure, and some contend that normal flexing while underway can result in stress failure of the conductors. Some of these reasons are why some authors recommend against it in their books and articles.

"Boat Cable" is similar to NM cable in that it has a non-metallic jacket and is about the same form-factor. One principal difference is that the individual conductors are stranded, not solid. This makes the cable easier to install, and many argue that it is more reliable because of the flexing issue (although note that the NEC requires NM to be properly secured, and reported problems due to cable flex are very, very rare).

The problem with most boat cable is that it is not "listed" for this use. The NEC requires all components of a wiring system to be "listed," meaning the manufacturer certifies the component as meeting specific standards, and that it is compatible with the other components in the system. In practice, the way manufacturers certify products as compliant is they submit them to independent testing laboratories such as Underwriters' Laboratories (UL) and request the product be certified to a particular standard. This is a very expensive process.

Manufacturers of boat cable, as a matter of course, also submit their products to UL and others for testing to standards promulgated by the US Coast Guard and/or international maritime standards bodies. As a result, the cable receives a type of BDFX and is "listed" for that use. Note that merely finding "UL Listed" on the cable does not mean it is listed for uses within the NEC, unless the specific NEC type marking is also on the jacket. Most boat cable is listed under UL 1426 and is marked "Boat Cable" and, e.g. "BC-5W2", which has meaning in the marine industry but is not in the NEC.

Coast Guard requirements are strict, marine environments are harsh, and the danger of fire at sea is orders of magnitude more life-threatening than land-based usage. In all probability, this cable, in most cases, would also meet NEC standards for certain types of cable assemblies (e.g. Type NM). BUT THE MANUFACTURER HAS NOT SUBMITTED THE PRODUCT FOR THIS TEST! The fact that the product would most likely pass does not endow the product with the proper listing. And the simple reason why the product has not been tested is that there is a cost associated with testing that will not be recovered through sales -- boat cable is made for boats, where it is required. Type NM, which is cheaper by about two thirds, is made and listed for homes (and RVs), and boat cable manufacturers are not going to achieve any significant additional sales of their boat cable by asking UL to also test it to NEC standards.

Some people have argued that, since testing to Coast Guard standards is, in many ways, more rigorous than testing to NEC standards for Type NM, that Boat Cable is therefore actually "better" than Type NM, and any legal challenge to its use in a bus could easily be won on that basis.

The problem with this reasoning is that it presumes that the NEC is concerned only with the quality of the material in question. The code, however, is also concerned with the compatibility of the all the components in the wiring system. Part of the certification of a component such as a cable is the certification that it will work as intended with the fittings and devices for which it is designed. As an example, Type NM cable is permitted to be used with listed NM fittings, while Type AC cable is permitted to be used with listed type AC fittings. But if you run a type AC cable to a junction box, and then connect the cable to the box with a type NM fitting, you have violated the code, even though both are permitted types. This violation would be obvious to even the untrained eye -- AC cable does not fit properly in NM fittings.

My point is that the quality of the cable is only one part of the approval process. If one chose to use Boat Cable instead, what fittings would be "approved"? Would one just use NM fittings, because they "look right"? How would one know, for example, that the coating on the outside of the boat cable has the right characteristics to be mechanically secured in a type NM fitting without slipping out?

So is wiring with Boat Cable safe? Maybe. I'm not a testing laboratory, and I personally won't stand behind a statement that boat cable is safe to use in a house (including RVs). Is it to code? Absolutely not -- for the simple reason that the manufacturer has not listed the product for this use. Is it legal? Depends on where you are, where you did your conversion, and who cares enough to raise the issue.

If you have concerns about solid conductors and prefer to use stranded cable, there are many alternatives that are stranded and also UL-listed to NEC standards. For example, type THHN stranded cable, when installed in a listed and approved conduit such as flexible metal conduit or liquid-tight flexible metal conduit, is an approved method. While more costly and labor intensive than installing integral-jacket cables such as Type NM (or metal-jacket cables such as Type AC or Type MC), you would get the benefits of stranded wire, plus the benefit of being able to remove, replace, or, in some cases, add wires long after your conversion is complete.

Lastly, I need to address the issue of wiring with extension cords: These are not to code, illegal in most jurisdictions, and UNSAFE, whether in a boat, a coach, or inside the walls of a house. Here's why:

Manufacturers of extension cords design and rate their cords for use uncovered, in free air. The design of the cord encompasses the gauge and ampacity of the copper conductors, but also the thermal and chemical properties of the insulation, sheathing, strain relief, and jacket. The cords are designed to carry their rated current only when the internally generated heat can be conducted through the insulation and into the environment. If the cord is covered in any way, either by being buried in a wall, or worse, directly inside of inflammable foam insulation, it is being asked to do something for which its insulation was not designed or tested: conduct heat into something other than free air. Many, many fires have started in extension cords that were improperly covered, costing hundreds of lives. The insulation on these cords ignites easily, burns hot, and produces highly toxic gas. Don't do it -- it's not worth your life, or that of a loved one.

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About The Author:

Sean Welsh holds a Master's Degree in Engineering from Stanford University. He recently retired from the telecommunications industry, where he held a variety of operational and engineering responsibilities. He is a regular technical contributor on the MAK [and BNO] BBS and lives on the road in his converted Neoplan with his wife and three pets.

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CPSC also estimates that about 3,300 residential fires originate in extension cords each year, killing 50 people and injuring about 270 others. The most frequent causes of such fires are short circuits, overloading, damage, and/or misuse of extension cords.

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Why is it, that it has to pointed out that "hundreds of deaths", or "campgrounds burned to the ground", has to be tossed in?

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I just wish you'd have more faith in your peer's ability to use their own common sense, after they've been given the information they need to make that informed decision.

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... a dedicated refer with GFI and 15A, a dedicated hot water 20A with GFI, a dedicated battery charger 20A with GFI ...

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