Archive for February, 2010

Mirror adjustment

How do you adjust your mirrors? Most drivers adjust mirrors so they can see a reference point in the mirror. For side mirrors, that means they can see the side of their vehicle. Car and Driver suggests that this might not be the best way to cover blind spots. You don’t need to see your own vehicle in your rear view mirrors, you need to see as much of what is adjacent lanes as possible.

A caveat for RV’s, especially trailers, is that the centerline rear view mirror usually cannot show what is directly behind you. Many states require that you have two mirrors that can see to the rear and that you be able to see the road 200 feet behind the vehicle (JeepForum has a thread on mirror laws as an example). While there is some interpretation as to whether this means that you have to be able to see something in the center of your lane 200 feet behind you or not, it does mean that your mirrors have to be far enough away from the vehicle to be able to see around your trailer and that they must be angled such as to be able to see straight back. That means that, without a centerline rear view mirror, RV’s need the mirror adjusted so they can just barely see the side of the RV and additional external mirrors will be needed to help cover blind spots in adjacent lanes.

It should also be noted that many states have restrictions on video screens viewable by the driver and this restriction means that using video cameras for rear view mirrors is not allowed when on the road.

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Watch out for supposed experts

Whenever someone thinks they know more than the manufacturer of a device or about the codes involved, you need to be very careful that you really know what is going on before doing anything. Howard falls into this trap in the February Blue Beret when he suggests modifying Honda gensets to implement neutral to ground bonding when the small Honda 120v gensets do not have a neutral to start with.

The lesson is that you need to be very careful in listening to recommendations from ‘experts’ and make sure you really understand what is going on. Be especially careful when the experts starting tossing around ‘safety’ as the primary reason for their recommendations.

There is no need or reason for an earth ground with a portable genset. The chassis grounds of the genset and the RV are connected together by the cord and plug ground wires and that is sufficient to provide a proper frame of reference for the fault detection circuits required in modern equipment. The reason for earth grounding is with grid attached power where the earth ground, chassis ground, and neutral are connected together only at the service entrance. This is why your RV circuit box does not connect these together as it is a sub panel and not a service entrance. The grid has long transmission lines that couple it to the earth which is why it needs careful earth ground considerations. Your RV on its own, off-grid and local, power systems does not have that problem and, hence does not need earth grounding for power safety.

You do not have a safety hazard as long as the power circuit is isolated from your RV frame and the earth ground, despite what Howard says. This is why the code is as it is for small gensets or other power supply devices (like battery powered inverters).

Your 3 light circuit indicator is designed for grid power. When using small gensets with plugs, it is entirely proper for it to not show a light for hot to ground voltage as the hot and neutral sides of the power may be isolated from everything else. Like with the voltmeter, you need to use the proper test equipment and properly interpret their readings in the context of what you are doing.

The column also gets into the problem of a genset not being able to power things such as air conditioners and microwave ovens. The lesson here is to watch out for oversimplification. The reasons why a 3kW genset might not power a 1.5 kw microwave include many factors. Altitude effects on genset performance is one. The appliance power factor is another. Power startup surge might be another. Hidden loads (the fridge going to electric is a common one) can be a source of failure. Even the type and length of extension cord you use between the genset and the RV can be a factor.

When you have larger gensets or wired in gensets, then you should have a transfer switch that will automatically make the proper connections.

Note that circumstances determine how things are done. Single phase small 120v portable gensets that use plugs are not the same as house backup systems or contractor power. Sometimes you know the generator is completely independent of any other power source or not. Sometimes, especially with portable equipment, you do not know for sure it is really a ‘separately derived system.’

A 2-wire 120 volt system has no neutral and therefore bonding is optional. Recall that neither side of a 2-wire derived system is a neutral and when one grounds either side, it becomes a grounded terminal or conductor, but it is not a neutral. (OSHA 1993 clarifying letter)

Definitions of terms such as neutral and ground confuse people, too. A neutral is halfway between the two sides of a split phase 240v system, not an arbitrarily selected side of a 120v system. Chassis grounds and earth grounds are two separate things. Unless you and the expert are very careful with terms, confusion can result.

There is a lot of bad advice out there. Forums and discussion boards are particularly poor sources as they don’t do any filtering. Magazine columnists can also go astray. It is up to you to properly qualify what you find by using sound logic, gaining a proper understanding, and using multiple sources of information.

See Also

see OSHA Grounding Requirements for Portable Generators and Using Portable Generators Safely

PORTABLE GENERATORS AND OSHA CONSTRUCTION REGULATIONS is by “Grizzy” Grzywacs at the OSHA National Training Institute. He had a ‘discussion’ on RV.NET where he very patiently went over the genset grounding issues with some recalcitrant objectors and that provided a good tutorial that is summarized in the paper linked here. (the RV,NET blog has the same bad advice as the Blue Beret, though)

Solid Grounding For Your Generator thinks through some of the issues. Another EC&M column on this is about how you should treat the neutral conductor. Mike Holt also talks about the National Electric Code on Neutral to Ground connections to describe what the code says.

The IMSA describes Generator Grounding and when ground rods are required at portable generators. The article carefully describes what a “separately derived system” is with illustrations. Also note

“Portable generators are covered in Section 250.34 Portable and Vehicle-Mounted Generators. This section allows the generator or vehicle frame to serve as the grounding electrode when:
(1) The generator supplies only equipment mounted on the generator, cord-and-plug-connected equipment through receptacles mounted on the generator, or both, and
(2) The non–current-carrying metal parts of equipment and the equipment grounding conductor terminals of the receptacles are bonded to the generator frame.

If the generator neutral is grounded then the generator can only be used with a transfer switch that transfers the neutral, or as a stand alone generator for a carnival or special even, and then ground rods are required.”

Generator Joe also has some good ideas for the proper operation of your portable generator.

With I’net searching, it is easy to find good resources to use to understand technical issues. Don’t get caught by bad advice, even if it does have the imprimateur of print in a journal or magazine. Electrical power is nothing to mess with so don’t think you know more than the NEC, OSHA, and the OEM unless you have the background and the resources to outweigh those authorities.

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Caravan memorabilia

One way a club rewards participation is with memorabilia. Here are a few examples from the Monterey Bay California Unit of the Wally Byam Caravan Club International collected by Dale and Virginia during the 1980’s.

see the photo gallery!

Some of these are crafts projects, some advertising specialty like items, some just home-made certificates and recognitions. What does your club do to reinforce participation and have fun at the same time?

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SNU February Newsletter

SNU Folks,

The February 2010 Newsletter has been posted. Note: Links to photo galleries and additional information mentioned in articles in this newsletter can also be found at there, too.

February Luncheon at El Charro

The next SNU lunch is Saturday February 27, 2010 11:30 am luncheon at El Charro. Located on South Carson Street, south of downtown Carson City, NV fees: $15 per person. To RSVP: hq@sierranevadaairstreams.org or call 775 972 5011. See you on February 27th.

In the February newsletter

Cabela’s Lunch -|- February lunch at El Charro -|- Message from the President -|- The Poll’s Airstream -|- SNU 2009 Highlights -|- WBCCI International Rally -|- SNU announcement list -|- Caravan in Nevada -|- Open invitation to members

-> For the latest on the Sierra Nevada Unit, check the website SNU homepage:

-> Check Zephyrs and find out what else is new on the SierraNevadaAirstreams.org


SNU HQ

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Your legacy and your assets online

Alejandro Martínez-Cabrera, Chronicle Staff Writer at SFGate discusses the problem of how Web sites deal with digital assets after we die. Do you have a contingency plan so someone can easily take care of your online presence if you die or are incapacitated? Who knows the ID and password you use to access online banking or investment accounts or how to obtain them? Do you have instructions that someone can use to notify your friends and correspondents of your status if need be? What should be done with the user accounts at social or shopping websites?

And how do you protect this personal access information while on the road yet still have it available with use instructions in a safe and secure manner? No longer is it the family lawyer with a will in his safe. Exactly what it will be is being figured out. Martínez-Cabrera describes some of the options being tried. A first step is just being aware that the problem exists and that is where you can start.

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