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Old 03-10-2015, 10:06 AM   #71
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Buy.
The.
Book.
No Shock Zone
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Old 03-10-2015, 11:27 AM   #72
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Good write up except the for the service drop (3 wires coming in from the utility pole does have a bare neutral wire, it is not just for strain but an important part of your service. (at least in Wye system) Maybe a Delta system is different???
Quote:
Originally Posted by taskswap View Post
You don't have a choice. For safety reasons you really need the biggest, most available chunk of ground material (the chassis) to be the "ground" in your AC system. It is possible to pick up some noise this way, but in practice this is less of a big deal than a lot of people think. A bus is a HUGE ground path.



Electrical boxes (usually) have two bus bars, bars with lots of holes and screws to attach neutrals and grounds to (the hots go to the breakers, of course). "Bonding" means the neutral and ground are tied together. This is the default in a lot of cases. However, NEC calls for some circuit configurations to be "unbonded", which means the connection between the two needs to be separated.

The circumstances in which this is required aren't 1-sentence-summary material. The ultimate goal is to make sure the ground wire is always "available" for its safety purpose and not actually carrying current at any one time. You should be able to grab ahold of it and not get electrocuted, even sitting in a bathtub full of water. That's why it's usually bare, not insulated - it's supposed to be a safety wire, not a current-carrying wire.

Neutral IS a current-carrying wire. They're tied together at the main panel in a house, for example, because that's the final exit point of electricity. There's a ground rod tied in there, too. Few houses actually have a true "neutral" out to the pole, especially in the US. If you look at the wire into your house you'll see it's actually just two conductors, one for each side of 240V. Your ground rod creates a "center tap" between the two that lets you get 120V out of each. Those wires to the pole aren't hot and neutral - they're both hot. And the steel carrier cable isn't hooked up to anything.

Anyway, that means neutral and ground are the SAME THING in the main panel in your house - and probably should be in your RV, too. But only at that one location. In almost all configurations, everything downstream (sub-panels, other boxes, etc.) should be "unbonded". Current should never be allowed to jump from neutral to ground anywhere other than at that panel. The reason is that if your neutral breaks (and wire breakage is one of the main failure modes these things are designed to deal with), you do NOT want current jumping over onto the ground wire and making that, essentially, a "hot" wire on the way back to the panel. Fires, electrocution, and other unreasonably nasty things await.

I haven't even begun to get into how this is all supposed to work - I'm paraphrasing, and I'm not even an electrician myself. If you're at ALL less than 100% certain how this should all be wired, consult one! Most charge < $100/hr, and since you aren't going to be getting a CO for this stuff, an hour or two of consultation is probably all you need - they're not going to sign off on anything. It's totally worth it.



A GFCI can be installed anywhere - it's usually point-of-use (in the bathroom, kitchen, etc.) There are GFCI devices that can "chain" or be installed "upstream" - examine your device for installation instructions.

Yes, your upstream wire needs to be able to handle the total capacity of what's in the panel.



Yes, but the further apart, the better. Actually, it turns out to be more important to consider where they CROSS than where they run PARALLEL for very long-winded explanations I won't get into here (but a CAT5 cable installer knows all about). A few inches apart is actually remarkably good at isolating noise. If you're really concerned, throw in a few lengths of EMT conduit. It's cheap, easy to cut, and if you ground one end (JUST ONE END) is a very effective noise isolator.

Grounding both ends can make ground loops - do not do this thinking it will be better.
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Old 03-10-2015, 11:33 AM   #73
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lorn

thanks, did not know about THE BOOK
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Old 03-10-2015, 05:23 PM   #74
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I read the book too, years ago.

I will not use the body or any metal of the bus as a ground. All grounds will be isolated from the metal in the bus.

I will be using all plastic boxes. No metal.

Every wire will be in plastic conduit.

The way most RV's are grounded is poor at best. I will be using a ground plate in the moist earth, or a ground plate submerged into a pond for a good ground.

If you don't connect any grounds, ect to your bus, you will have no chance of hot skinning. A energized bus is the last thing I want.

Nat
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Old 03-10-2015, 07:32 PM   #75
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Lets see if I can explain this clearly. Disclaimer: I am not saying anyone is wrong or right. Just there is a right way and a wrong.

1. If you are boondocking your power source is you. Meaning your power comes from batteries, or solar, or generator, or squirrels in a cage on a wheel. The DC system must be complete, including a ground back to the source. No ground no worky. The AC system must have a neutral to return to the system and a ground to protect it.

2. In modern AC systems you must have a hot, neutral, and ground. Hot supplies power to what ever, neutral is the return side in a modern system, ground protects you and your love ones. So by all means do you proper grounding, ground to the chassis.

3. Fuses are designed to protect the circuit not the user. The ground is meant to protect you. If you eliminate the ground we have fried person. If a short occurs then the ground now works as the return for the power and fuse blows as current is excessive and this saves people because shorts don't live with grounds.

4.Neutrals should be controlled by your inverter, (note to self: if you don't have one you wont have a safe boondocking AC system). All quality mobile inverters have a neutral switching provision. This means when boondocking the inverter takes care of the proper bonding issue. When you start you gen set, it again takes care of your proper bonding and yes when you plug in at the camp ground (after checking your site plug in) it again does its job.

In summary its my opinion that chassis ground is required for both AC and DC. If you are going to bother to build your way skimp on anything but the inverter (again my opinion). If you want to skimp on the inverter then learn how to make a relay controlled neutral switching circuit for neutral bonding. Before you by that fancy inverter gen set remember they do not bond neutral correctly and see above recommendation on cheap inverters.
Lastly yes you can have a different opinion then me, Its okay to be different after all we are skoolies.

Have a great day
Chuck
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Old 03-10-2015, 08:00 PM   #76
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What he said. Also, those "quality" inverters deal with phase-matching, too...≈
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Old 03-11-2015, 01:07 AM   #77
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I read the book too, years ago.

Nat
Really? "No Shock Zone" publish date was Jun 16, 2014
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Old 03-11-2015, 10:44 AM   #78
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Quote:
Originally Posted by lornaschinske View Post
Really? "No Shock Zone" publish date was Jun 16, 2014
Really, I see a 2010 copy right.



Nothing about electricity has changed recently, so why do we need new publications? Just one more interpretation of the same thing.

Grounding any of the AC power to the metal of the bus is a mistake IMO.

Why would you take the chance of energizing the metal skin of your bus?

Residential electrical is always properly grounded with a ground rod, or ground plate. What is wrong with doing this in your skoolie?

My stabilizer jacks are steel and touch the ground, unless I set them on a wood block. This is essentially a ground. However, not a adequate ground IMO.

Residential AC systems don't have a ground running from the transformer to the house, only two hot leads. Grounding is done at the house with a ground rod, or ground plate.

Many industrial systems don't even use grounds. They are far more reliable this way.

All my DC grounds including the buses wiring harness will also be isolated from the buses metal body. This makes for less electrolysis (RUST), and a safer, more reliable DC system.

My inverter will be far from cheap. It has what is necessary for the neutral bonding.

As long as your grounding your AC to your metal bus, you risk electrocution. All it takes is one wire in your shore cable to become damaged, or a faulty wired item to be plugged in.

Like it's been said on here. The ground is the safety for the user. Please be safe.

Nat
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Old 03-11-2015, 11:12 AM   #79
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I personally don't like ungrounded systems, although they do have some good. Navy Veteran here. All US Naval ships are ungrounded systems and well really suck as far as electrical goes. And have you ever worked on an old Corvette electrical system. Arrrgghhhh... Just my opinion here...
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Old 03-11-2015, 12:37 PM   #80
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Really, I see a 2010 copy right.

Nat
Those are the online articles. The book is much later...
http://www.amazon.com/No~Shock~Zone-...=no+shock+zone

Paper back has an Aug 2, 2014 date

You are the reason I first posted links to No Shock Zone in RV Electrical Safety.
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