What’s causing these van /trailer fires?

[Qxxx]

Say Spiff, looking at it from the other way around. If I had something like a frig or whatever, and wished to shock mount the entire unit by putting it on some foam or other cushioning material resting on the van floor, what would you recommend using, and how thick?

Personally, I don't think memory foam would be worth poo, as it compresses into a hard rock surface from my experience. So I am thinking of something along the lines of sleeping pad foam, 2 or 3 layers thick.
https://www.walmart.com/ip/Ozark-Trail-Closed-Cell-Foam-Blue-Camp-Sleeping-Pad/634956813

So let's say I have a typical unit 36" long by 12" wide, and weighing approx 20 pounds. Got an idea?

 

[highdesertranger]

Q that wiring in your condo is a no-no. the AC and the microwave both should have their own dedicated circuit. putting 2 high draw items on the same circuit is a no-no.

as far as the wires coming loose that is quite common with pinch type terminals. on the apartments I work for we go through the breaker panels every 5 years and tighten them. you would be surprised how many are loose and like you said apartments don't drive down the road. that's why I always recommend against using those type of terminals. car audio components seem to be stuck on them.

highdesertranger

 

[Qxxx]

Well I know not to install the microwave that way, but it was previously installed that way. By "pinch type terminals", you mean crimped? I guess home builders have their own methods, with those metal sleeves for making junctions. ???

Ha, I remember one guy on youtube showing how to build your own heavy-duty battery cables, 1 or 2 gauge. "Slide the stripped wire into the terminal lug, and wap it with a hammer".

 

[highdesertranger]

this type,



they make this type of termination for fuses,  circuit breakers and all kinds of stuff.  avoid these type of terminals.

highdesertranger

 

[Qxxx]

Ah so, not seen that type but everything is held by screws which can loosen over time. But I can see how it's quicker than other means, so get in, do it quick, take your profits, and move on to the next job. Money, money, money.

 

[ZoNiE]

Just for fun I thought I'd show these pictures. I live in a 30 yo condo, and when I moved in, the AC outlets were all yellowed, so I sought to change them out. What I found ...

1. Literally on one half of the outlets the screws were loose. Why? Who knows.
2. On one outlet, they had branched the wire going to the microwave off the outlet. As the screws were loose, you can see the result below when I looked inside.

And of course, the condo has never driven down any bumpy roads either.

At least those were not "backwired" but the screws come loose over time, heating and cooling of the dissimilar metals (Cu and Brass) can cause that.

 

[B and C]

Those wires make me wonder what the breaker size is in the panel. Just from the internet eyeball I have here those seem to be 14 gauge wire and should have a 15 amp breaker. Heating up and cooling down numerous times will loosen those screws. The electricians here seem to use the stab connections on the back of the outlet. Those are spring powered. My microwave outlet has a 20 amp breaker on a 12 gauge wire (dedicated). There are 15 amp and 20 amp outlets too. The wires for a 20 amp (12 gauge) circuit will not fit in the stab connections of a 15 amp outlet.

 

[Qxxx]

All of the breakers in the condo are 20A, except for 15A in kitchen and bedroom. I'm pretty sure the reason this outlet caught fire is because the microwave didn't much like arcing across loose screws. I'm guessing microwave magnitrons or cavitrons are a bit finicky that way. Probably big turn off (lightning) arcs.

That installation is just of a number of horror stories left over by the previous owner. Eg, he wired an outlet so the top half could be turned on/off with a wall switch, but forget to remove the shunt between upper and lower sections of the outlet. "WTH, the on/off switch never turns it off. Oh well, on to the next problem".

Which brings up the issue of ... who owned your RV previously? Who installed the microwave? Who installed the frig and solar? (not meaning yours specifically, Brian, lol).

 

[Qxxx]

Oops, meant to say "except for 15A in bathroom and bedroom".

 

[B and C]

So those 20 amp circuits have 12 gauge wire? I hate working with 12 gauge, it is very stiff.

 

[Spaceman Spiff]

Say Spiff, looking at it from the other way around. If I had something like a frig or whatever, and wished to shock mount the entire unit by putting it on some foam or other cushioning material resting on the van floor, what would you recommend using, and how thick?

So let's say I have a typical unit 36" long by 12" wide, and weighing approx 20 pounds. Got an idea?

I will assume from your comment of the refrigerator 'sitting on the floor' that it is a chest type.  An upright that is higher than the length or width measurement would be harder to protect.

Assuming it doesn't tip easily and a weight of about 100 lbs. (loaded) the pad you linked to should work. Double thickness (1") would be better but not necessary.  If the refrigerator is in a place where it could hit something else (e.g. the side of the van) you might want to cushion in that direction also.

Remember you already have a lot of shock dampening with the suspension of your van.  Good shocks and springs and lowering the pressure of your tires (and your speed) when on a bumpy road will attenuate a lot of the energy of bumps.

With an tall upright you have the additional problem of it rocking back and forth and tipping over or hitting something else, causing a secondary shock that usually is more violent than the first.

Commercially styrofoam is used almost universally as shock and vibration protection in shipping.  We used styrofoam to protect hard disk drives during shipping and used a 4 footed drop test in their shipping containers; much more violent than any reasonable use in the field.

 

[Qxxx]

Hey Spiff, thanks for the response.

I've always wondered why "stiff" styrofoam, universally used, acts as a good shock absorber, as opposed to say some sort of medium firm compressible foam. Can you address that?

You often see specific 1/off containers having compressible foam, but packaged items always coming in styrofoam.

Also, good point about having padding on the sides of something like a chest style frig. I should think that using some of that sleeping pad foam "both" under the frig and also on the sides would improve its cooling efficiency too. Win, win.

 

[bonvanroulez]

What exactly are you hoping to mitigate with foam under/around a fridge? Are you saying a 12 volt or 120 volt (not propane) refrigerator in a van/rv is a fire hazard if it doesn't have some additional shock mounting? What is the failure mode being discussed here?

 

[Qxxx]

This has been addressed in "many" earlier posts in this thread.

 

[Spaceman Spiff]

Hey Spiff, thanks for the response.

I've always wondered why "stiff" styrofoam, universally used, acts as a good shock absorber, as opposed to say some sort of medium firm compressible foam. Can you address that?

You often see specific 1/off containers having compressible foam, but packaged items always coming in styrofoam.

Also, good point about having padding on the sides of something like a chest style frig. I should think that using some of that sleeping pad foam "both" under the frig and also on the sides would improve its cooling efficiency too. Win, win.

Why styrofoam?
 - The raw material (styrofoam beads) is cheap,
 - Forming it into odd shapes is easy,
 - The tooling to make shapes is inexpensive as is the process,
 - It is light (doesn't add to shipping weight),
 - And when tightly constrained inside a box it is a very good shock damper.

We also used different foams to package hard drives.  It would usually be which vendor could give the best price.  Open cell foam has the disadvantage of holding moisture, which didn't bother us because the drives were sealed in a anti-static bag.  Foam has the advantage that you can cut holes in it to hold parts.

We did use expandable foam bags for one-off shipping; put 2 or 3 into a box, put the hard disk in, pull the strings and the foam in the bags expand to nestle the part very tightly.  Expensive, but cheaper than making one-off tooling.
Packing peanuts were also used for one-off shipping.

 

[Qxxx]

Thanks, Spiff. Sounds like closed cell foam is the way to go for padding things in a van.

FWIW, I am amazed at things people do with their RVs. Here's a couple that pulled their TT 6 miles up a washboarded road near Sedona. "Well, we could have camped near the highway, and we had the walls popping loose from all the bumping and had to push them back in place, but we wanted to be near the pretty colored rocks". Be Cool.

 

[jacqueg]

OMG!!!! We have to drive so slow! 

Quelle horreur!