B+ motorhomes

[Daniel_C_]

I just bought a Trail Lite B+ 211s with 8.1 Chevy
engine. This is my fifth motorhome (others range
from an old 20' Vagabond, and three Winnegagos, from 19 to 32'. This vehicle is fantastic. I am
using it as a mobile office (and sneaking in a fun
journey from time to time). It gets about 9.5mpg
and I believe I could pull a bus behind it if I wanted! I paid low $40's which is about what I had expected to pay for a five or six year old Chinook with a nicer interior, but fewer features
(slide). I am delighted thus far.

[burlmart]

Larry, I'm also a CE, and that is one reason my electrical know-how is pretty feeble.

[TrueLarry]

Molded plugs of all sizes, I have discovered are pretty bad. I have an electric high pressure washer that I ran for about four hours on Saturday. When I finished I discovered that the plug was partially melted and distorted even though the cord itself was cool as a cucumber the whole time. For a time I had it plugged into an extension cord and discovered that the receptacle end of the extension cord was also hot though not melted. Burlmart's lesson learned is a good one for all of us. Even though I'm an engineer (civil) I tend to forget some of this electrical stuff. Thanks, Artum, for the great explanation.

[burlmart]

Excellent description Artum! That explains a lot to me. Though technical, you put it in practical terms very well.

Yes, Cheese, I am saying the outer black insulation of the big shore power wire from the RV which used to fit snugly into the big molded 30A plug is not only not inserted into the plug, but comes short of meeting it and there is now a gap of 1/8 or 1/4 inch and I can see the inner colored wires.

I may have stretched it somehow to cause the separation?? But when this discussion (and I think one on the general forum) recently mentioned heat at the plug at the CG, I recalled a time or three where I thought it was unusually hot to the touch (I think it was at Henderson Beach SP in Destin).

[cheeze1]

Yes Artum, my breaker tripped...a number of times.
Your discourse is spot on. As a former Industrial Arts Teacher and wannabe engineer, I follow all that you have said. Tho' I forget the formula on occasion, (usually on occasion that I need it!) 😉 I applaud the clarity of your explanation.
What's also interesting to me is the relative 'fragility' of aluminum, that the average consumer only is aware of when they crush a soda can in their hands. When I taught Metal Shop, I had foundry area where aluminum was the metal of choice. I was amazed at how easily aluminum melted. That aluminum can?-believe me they weren't worth the effort as a raw material. I did cast brass a couple of times, almost double the temps and the pour was pretty exciting. I still have one of the projects. Anyway, it now doesn't surprise me how easily that buss bar melted. The wires were fine, just burned insulation.
Hey! I just noticed you have a Triple E?! They are supposed to be great units!

[Artum_Snowbird]

Well, to get a bit technical, I am an electrician by trade, industrial mostly.

But, the resistance within a circuit is made up by all the individual parts. Heat is calculated as I (current)² times R (resistance in ohms).

Normally wire and connections to and from the load would only add possibly 1/10 of an ohm or so over the entire length of the wiring and connections. Spread over all the wiring you can calculated I²R to be at 30 amps 30 X 30 X 1/10 = 90 watts

But if you have a weak link, like a frayed connection in a molded plug, or a loose connection in a buss bar, that loose connection may individually cause a resistance of a half ohm. Suddenly just in that one spot you have 30 X 30 X 1/2 = 450 watts. Knowing how hot a light bulb gets, imagine all that heat on that melted buss bar, or feeling that hot plug, imagine how many light bulbs it would take to get that hot.

The most dangerous part of all this is that the voltage starts out at 120 volts, and when the circuit is running fine, the loads on the line see almost 120 volts. But when you have a load like a bad plug or a melting bussbar, that load takes (at 450 watts) about 15% of the voltage, leaving only a little over 100 volts to run your fridge, air cond, etc... The available power in the circuit is robbed by the faulty connection, so everything else doesn't get the power needed to do what it's supposed to do. That causes compressors to struggle with trying to overcome the built in resistance, the more it trys the hotter it gets, the hotter it gets, the more resistance in the wires, until something gives...hopefully the breaker trips before the motor burns out.

[cheeze1]

No, it may have nothing to do with it. One reason I understand Artum's idea is that I've had many premolded plug/wires from power equipment that separated because of usage/lack of quality. If you have noticed unusual heat there, then you might have the culprit. No heat, then its a safety and to a lesser concern, cosmetic issue. Of course I'm assuming you mean the outside(black) cover of the entire wire.

[burlmart]

I'll look at both options. Do you really think my separation of wire to plug head is proof of an overheating due to bad plug head wire to prong connection?

I wonder how common this is?

[cheeze1]

I would guess that a replacement plug might have indications of which color goes where. There must be a guide that shows where each wire must be attached, since polarity must be observed, especially with an rv.
My experiences with replacement plugs have been good/bad, hence my recommendation to get a completely new wire. Artum has a good point tho' and maybe the answer if your wire is in excellent shape.

[burlmart]

Artum, that makes sense to me. Before all this came up, I was not aware that these molded plugs were poorly built.

You raise the bigger point that I forgot: I cannot tell which color wires go to which of the 3 prongs in a molded (enclosed) plug. I assume there are three wires, and maybe a universal color scheme, like green=gnd, white=pos, black=neg???

[Artum_Snowbird]

Sometimes true... but putting a good quality plug on a perfectly good cord might be a better alternative than buying another perfectly good cord with another cheap molded plug attached for less $$$.

[cheeze1]

I've seen them in HD. I have no idea of the prices, but sometimes repairing a wire is less cost-efficient than buying a new fully assembled one.

[Artum_Snowbird]

Burlmart,

You might find when you go to a big store like HD there may be choices galore. The 30 Amp 120 volt plug in you need is just that, but there are a great many three and four prong plugs and receptacles all for different uses. The 50 amp ones the big DP's use is a different plug, and there are many more, each for a unique application.

It is vitally important to connect the wires correctly if you replace something electrically. If you can see the connections from your present plug in cable, and the color of each wire and where it goes in your panel, you will need to know which terminal each goes under if you replace the cord cap (plug).

[cheeze1]

Burl, your breaker/fuse panel should be under your rear dinette seat right next to the sink cabinet. You need a torx bit (#10?) to remove the front panel. There is another panel held with 2 normal screws that surrounds the breakers. Remove that and you will find the buss bars. In addition, under the rear dinette seat (if the cover doesn't lift remove the screws) you will find another buss bar screwed to the floor. That's where I found one loose wire. The ones on the melted bar were too far gone for me to determine if any of those were loose/causing the problem.

[burlmart]

Thanks all. Good to see you here with us, Rodger, and thanks for the post. Now with you and Cheese suffering the same thing, I will be double motivated to check ours.

Cheese, will I have a hard time accessing the bus bars - I assume they are under my dinette seat that backs up to the kitchen (behind the breaker panel in the 'hallway')?

Artum, are you saying there are important differences among 3 prong 30A replacement plugs that I will need to research?

[cheeze1]

Rodger, thanks for the reference. Looks very similar.