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Old 04-28-2015, 01:45 PM   #121
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I've successfully used a heat gun to form PEX several times. IMHO, PVC pipe forms more nicely than PEX does, but they both accept it pretty well. Seems to me that the PEX is more prone to springing back than the PVC is. It took some practice to learn how to heat the pipe without blistering the surface, and how to heat a large enough area to just the right point so get a smooth bend without any kinking. I've kept an old toaster from the kitchen intending to dismantle and use its elements (nichrome?) to build a pipe warmer. Maybe it's time I actually did do that; there'll be plenty of places in the bus where a neatly bent plastic tube would be convenient.
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Old 04-28-2015, 07:05 PM   #122
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1/2" PEX, not so bad. 1" PEX (what I have lying around) is a cast-iron-SOB. Heat gun or no it still wants to spring back.
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Old 04-28-2015, 10:15 PM   #123
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Originally Posted by taskswap View Post
1/2" PEX, not so bad. 1" PEX (what I have lying around) is a cast-iron-SOB. Heat gun or no it still wants to spring back.
Use it to make a bow and arrow. lol

Nat
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Old 05-06-2015, 07:00 PM   #124
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Random grounding question, based on my experiences in military field communications. Everything that's painted green, from tactical generators to maintenance shelters and trailers, all have grounding lugs on the power input panel, in addition to chassis grounds. Would a grounding lug to earthed grounding rod at the shore power input help add a layer of protection from a hot skin?
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Old 05-06-2015, 08:41 PM   #125
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From an earlier post by jmsokol on this thread:

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And even pounding in an 8-ft ground rod really doesn't "ground" your RV. That's because the "ground" wire in the shore power line is really misnamed. It really should be called the "bonding conductor" which connects your RV chassis back to the service panels Ground-Neutral bonding point. This is what creates a high-current fault path which is what trips the circuit breaker to protect you from shock. Jack plates on the ground create a few thousand ohm "earth path" at best, when less than a 1 ohm fault path in the EGC is required by code. Even a properly installed ground rod can measure up to 100 ohms to earth and still be in compliance. It's really there to act as a path for lightning, and not as a ground fault path for 120-volt shorts. So yes, a ground rod DOES NOT ground your RV. Please don't argue with me on this because it's all in the NEC if you'll take the time to read it.
Having no exposure to military field comms I'm in no position to say what those grounding lugs are for. My guess though would be that they're kind of multi-purpose, to be used in a variety of ways depending on where and how the equipment is installed.
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Old 05-06-2015, 09:12 PM   #126
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I wasn't clear on how to do grounding for 120 volt either. Right now I have no connection from the 120 to the bus frame whatsoever (which I think is incorrect). So on one hand, if a + wire chafes through it will electrify the frame +120 and won't trip, but on the other hand if an outlet is wired wrong there is no way to electrify the skin. Not sure how is the right way to do this. I know there is a write up on it on here somewhere though.
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Old 05-06-2015, 10:12 PM   #127
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If a piece of equipment has a ground lug, grounding it is almost never the wrong thing to do. Most of the time grounding is "wrong" is when you only THINK you have a good ground but really don't. Numerous guides and videos talk all about what can happen if your electrical hookup has a floating ground and how many parks are mis-wired. I've never actually been to one that was mis-wired (we stay at a lot of state parks, without power at all, and KOAs, where they go By The Book) but I don't disbelieve this can happen.

The first step of educating yourself, being aware of, and taking responsibility for your safety (instead of just trusting an outlet... or a well written post on Skoolies.net!) is the most important one.
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Old 05-06-2015, 10:28 PM   #128
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Originally Posted by porkchopsandwiches View Post
I wasn't clear on how to do grounding for 120 volt either. Right now I have no connection from the 120 to the bus frame whatsoever (which I think is incorrect). So on one hand, if a + wire chafes through it will electrify the frame +120 and won't trip, but on the other hand if an outlet is wired wrong there is no way to electrify the skin. Not sure how is the right way to do this. I know there is a write up on it on here somewhere though.
Actually, to comply with both NEC and RVIA code, you need to have the Equipment Grounding Conductor (the ground wire) of in shore power bonded to the frame of your RV/bus. Typically that's done right inside of your AC circuit breaker panel with a big bolt tied directly to the frame. And as you surmise, without that ground-to-frame bond, it's surprisingly easy to hot-skin electrify your bus.
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Old 05-06-2015, 10:35 PM   #129
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Originally Posted by Scooternj View Post
Random grounding question, based on my experiences in military field communications. Everything that's painted green, from tactical generators to maintenance shelters and trailers, all have grounding lugs on the power input panel, in addition to chassis grounds. Would a grounding lug to earthed grounding rod at the shore power input help add a layer of protection from a hot skin?
A ground rod's job is primarily to protect your RV/bus from nearby lightning strikes. It does very little to protect you from a hot-skin condition in the event of an open safety ground. In fact, it will only have sufficiently low impedance to drain down a high-impedance/low-current fault that's not really a dangerous shock hazard. Any low-impedance/high-current chassis fault will overwhelm a ground rod without a proper neutral bond back to the incoming service panel.

So while a ground rod may make you feel better. There's really no practical reason for driving one. Also remember that you can't just drive a ground rod anywhere you like. You should contact Miss Utility or other similar group to check for underground wiring or plumbing.
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Old 05-31-2015, 11:34 AM   #130
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Wanted to chime in since grounding and bonding is a big chunk of what I do for a living.

“Grounding” is the connection of an electrical system to earth. “Bonding” is the connection of two conductive things together to make them electrically common. 99% of what we call “grounding” is actually “bonding”.

In a grounded 120VAC system, which is what all of us in North America are using at home, the neutral wire must be bonded to the ground wire (officially called the “Equipment Grounding Conductor”) at exactly one point, and that point also needs to be connected to the “Grounding Electrode Conductor” which goes to earth ground. There are rules about exactly where to do this in various situations, but generally speaking that point should be at the source of 120VAC power or as close as you can get to it.

If you bond the neutral wire to the ground wire at more than one point, you create a “ground loop” which causes some of the current to flow through the ground wire instead of the neutral wire. This is bad for several reasons including: trips GFCIs, causes EM interference for electronics, and is theoretically a fire and shock hazard. Don’t do it!

So in an RV (or skoolie), with a shore power source, the neutral wire is bonded to the ground wire at the upstream power panel that feeds the outlet you are plugged into. You can make sure this is the case using a cheap 3 prong circuit tester (though if you want to frighten yourself but ultimately be extra safe, also read this about reverse polarity bootleg grounds, a dangerous situation that results from two separate wiring screw-ups).

Therefore, you should NOT have the neutral and ground wire bonded anywhere in your RV 120VAC system because then they will be bonded at more than one point. You DO need to have your ground wire, NOT your neutral wire, securely bonded to the metal frame/skin of the RV.

With an inverter or generator source, though, since you control the source of 120VAC power, you are responsible for bonding the neutral and ground wire. You should do this AT the inverter or generator. Some inverters and generators do this internally; check with the circuit tester, or use a multimeter to measure resistance between the ground and neutral with the power off. Make sure that the metal frame of the generator or inverter, if such exists, is also bonded to the ground wire.

In theory you are also supposed to have a Grounding Electrode Conductor bonded to the neutral and ground wire at the generator or inverter. The purpose of the GEC is (a) to provide a direct path to ground for lightning strikes and (b) to keep the metal cases of things at the same voltage as earth ground. In practice, no one is driving 2 8 foot ground rods 6 feet apart or whatever when they set up their portable generator, and I wouldn’t do it either. I personally don’t believe you’re taking much of a risk by not having an earth ground on a temporary portable setup.

This does NOT leave you at risk of a true “hot skin” condition. You are protected from “hot skin” by having:
-A properly sized circuit breaker immediately downstream of your power source.
-Your ground wire bonded to your RV frame/skin.
-Your neutral wire bonded to your ground wire at your power source.

Hope this is helpful to somebody, I know it's a bit long winded, sorry! Best of luck setting up your electrical systems, it’s a confusing subject for everyone!
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