No earth grounding?

[timselectric]

We are not talking about grounding in general, but a very specific type and how it benefits an off grid application. Do you specific examples?

Grounding is for electrical safety. All electrical safety.
I really don't know what you have against safety. But please make sure that your wife is always wearing shoes. If you really insist on creating this Hazzard.
You have already proven the need for Grounding, when you both got shocked before.

 

[Drew888]

Grounding is for electrical safety. All electrical safety.
I really don't know what you have against safety. But please make sure that your wife is always wearing shoes. If you really insist on creating this Hazzard.
You have already proven the need for Grounding, when you both got shocked before.

I have no idea what you’re talking about.

 

[timselectric]

I have no idea what you’re talking about.

And it appears that you never will.
Good luck.

 

[Ampster]

The main benefit of an earth ground is to handle the static build up.

Even if you do not get a direct hit from lightning, the "static" build up on wires and metal parts can be significant from a nearby strike. This induced current and voltage can be directed to ground to avoid a shock hazard from touching energized devices.

 

[Drew888]

The static build up is supposedly not from lightening, but from the current running through the system. This is supposedly one of the most critical issues for a grid connection. Is it an issue for a non-grid and a small system?

 

[Ampster]

Is it an issue for a non-grid and a small system?

i was referring only to induced current caused by nearby lightning not static electricity per se. It is that significant voltage and current that can be dengerous even though there was no direct strike. At that point it does not matter whether a system is off grid or small.

 

[Shimmy]

The static build up is supposedly not from lightening, but from the current running through the system. This is supposedly one of the most critical issues for a grid connection. Is it an issue for a non-grid and a small system?

No, it is not about current it is about voltage. By the fact that the voltage of a lightning strike exceeds the breakdown voltage of air half-measures aren't going to work.

Look around your home and take an inventory of how many devices have ground pins on the plugs. All of them are going to need to be replaced with something double-insulated. Without that you have a dangerous environment. Oh, and you need to deal with the fact that your inverter is capacitively coupled to ground no matter what you do, so you need some kind of isolation transformer for you to really have a floating ground.

I've worked with floating grounds in critical facilities before... they are really a pain in the ass and require constant attention. A solidly grounded system is as set-and-forget as you can get.

 

[timselectric]

I've worked with floating grounds in critical facilities before... they are really a pain in the ass and require constant attention. A solidly grounded system is as set-and-forget as you can get.

I installed floating ground systems on marine vessels for many years. Definitely a pain to keep up with. 6 tests a day was the SOP.

 

[CoolWill]

This isn't a large grid generator.

And? Grounding small systems is also meant to limit the amount of charge that can build up in the area. Lightning rods aren't meant for direct strikes, they are meant to bleed off charge from the atmosphere before the potential becomes large enough for a flashover. A small solar system is grounded for both electrical shock safety (bonding) and to limit potential between different parts of the system, be it from lightning, or just static build up.

 

[Drew888]

For this application all of the components are grounded together by the neutral/ground and would have some capacity to dissipate some static electricity. Surface area and humidity are a factor.

A near by lightening strike is a concern for the equipment. Although the probability of a direct hit goes up exponentially with structures that are earth grounded. The trade off might be the equipment vs everything else.

Here is a hypothetical situation. Lets say we have two identical pick up trucks in a large field during a lightening storm. Truck A is just sitting in the field and truck B is connected by its bumper to a 6ft ground rod. Which truck would you want to be in?

 

[zanydroid]

In your non solidly grounded system, what protects you when static buildup pulls all metal chassis bonded to each other but not earth ground to above a touch safe level of voltage relative to earth ground? If you touch one of those frames in a location like dirt or concrete pad where NEC requires GFCI protection because of high probability of discharge to ground.

 

[Drew888]

We are specifically discussing structures that are not grounded. Wood structures on pier blocks, gravel or pavers, etc.

If it is a structure that is grounded or partially grounded from a pad, plumbing etc there is no negatives from an earth ground.

An off grid application’s AC & DC voltage would have no affinity to the earth.

 

[zanydroid]

Are you suggesting that the buildup is not possible in those structures, or the cost outweighs the safety benefit?

I don’t believe basic safety devices like GFCI can protect from this kind of discharge, and in their design they presume that EGC is connected to a GEC, therefore at earth potential. So potentially a lot of reinventing of basic equipment is needed

 

[Drew888]

It appears that the build up is much higher in grid attached systems. In an off grid system the only build up would be generated by the electronic components. Also is this a substantial personal safety concern?

GFCI is a low impedance sensing device. It will still function without an earth ground, just not between the earth and system. There would be no need to do so.

This is not a new concept. The most popular off grid systems are RV’s and travel trailers which do not incorporate earth grounds. These are hugely successful.

 

[ksmithaz1]

We are specifically discussing structures that are not grounded. Wood structures on pier blocks, gravel or pavers, etc.

If it is a structure that is grounded or partially grounded from a pad, plumbing etc there is no negatives from an earth ground.

An off grid application’s AC & DC voltage would have no affinity to the earth.

Pfft. Let us all know where to send the flowers.

 

[Shimmy]

We are specifically discussing structures that are not grounded. Wood structures on pier blocks, gravel or pavers, etc.

That is nearly impossible to acheive; generally what you end up with is loose or intermittent grounding. But, for the sake of discussion let's assume it is done.

It is generally ok as long as everything is dry. Once you add water into the mix, or bridge the house to ground via incidental contact then it becomes dangerous. Real houses have things that bridge to ground though (including people entering or leaving).

The only good reason to make a structure ungrounded is necessity (like an RV). It isn't going to help with static or lightning in any meaningful way.

 

[Drew888]

I’m not really following what you are saying. What is the safety benefits for this application? This is still high impedance grounding.

 

[sunsurfer]

I’m not really following what you are saying. What is the safety benefits for this application? This is still high impedance grounding.

The idea is to not connect things like panels to the earth with ground strapping, etc....and also insulate where possible.

The goal is to avoid any step leaders that can reach out to the charge above coming down from the sky. Once a step leader makes contact, the full force then will follow that path giving you a strike. Many step leaders can form but the first to make contact takes the brunt. There is a famous photo right before full lighting strike of a farm house. You can see the little leader charges coming off of trees, building corner, etc...reaching towards the bolts(charge)coming down form the sky.

They tell hickers if your hair starts standing up, squat down with your feet on top of your back pack. Make yourself as short as possible while trying to insulate yourself from ground