i sorted out the generator ground thing

Started by jibberish, December 15, 2011, 03:05:51 AM

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jibberish


I studied the OSHA article on generator grounding, and meditated on what everyone collectively said.
I made sure i understood this new term to me "bonded"
and finally i meditated on what OSHA is all about to try and get clear on wtf is up with this. OSHA is about what happens when the shit hits the the fan, they want things to fail to the safest state possible.  from working on conveyors, SOP is to make sure things fail off or closed or non-energized or in the down position, etc etc etc to minimize someone getting hurt.

ok then it all did get clear regarding the generator vs grounding vs bonding vs no ground scenarios.

first some terminology needs to be defined:

Bonded: this is an electrical connection to a common or non-earth-ground, ground-plane. i had not come across this term before myself. so hey, learned a new one.

Fault: a fault is a circuit, but a bad one where juice is going where it isnt supposed to be going.
so if the "power supply faulted" something shorted out or w/e in the power supply etc. if you get zapped by a ground-fault, you incorrectly/un-intentionally conducted juice through yourself to the ground, and obviously that's bad. heh.

ok WRT (with respect to) the generator scenarios faulting, there are 3 cases.

1) stand alone isolated generator with no conductive superstructure in close porximity, with only stand alone plug-in devices plugged in.

if you are out in the woods and your flourescent light shorts out, the electric is contained starting out the power cord, through the guts of the light and back down the power cord. so the hope is the circuit breaker kicks out while this mess is just burning or w/e by itself.

the generator frame , or designated piece of metal or screw like in a plastric housing IS the common for devices to be grounded/commoned/bonded to lol

if you put a stake in the dirt for an earth ground, you noww have needlessly made the dirt a potential circuit in case of a ground fault. so they all say do not use earth stake ground.

2)  generator on a vehicle/trailer. ok so the un bonded generator is powering stuff all over the big camping trailer. if a cord maybe gets cut rubbing a sharp metal edge and maybe faults the black wire to the entire trailer frame, we now have a potential ground fault circuit should anyone using another power deivce and touching the grounded housing, if they touch any metal , they get fried. So the fault scenario of an unbonded generator is potentially lethal.
the generator common needs to be bonded to the metal frame, which is everywhere, so if there is a fault like that , once again the hope is the breaker quietly kicks when the black initially touches the frame. no harm no foul

3) house/structure.  the whole house is set up with earth ground commons, like all the plumbing and possibly hvac ductwork, metal structural framework, other types of comms wiring etc.  anyway, this is anothe case of the superstructure haveing a big continuous circuit all throughout. and once again if, generator hot gets onto the earth-dirt-plumbing ground plane, anyone anywhere else in the house could get it from a grounded-to -the-generator  device and touching the ground plane.

so, the generator must be staked to earth ground, so once again, if the black wire faults to the ground plane, the generator get shorted out and the breaker quietly trips.

i would guess ayek's deal is that there is structure, like a stage with metal or something venue-structure like that has the potential for creating part of a fault that zaps someone. i would also guess they specify big energy equipment gets earth grounded too to eliminate the ground fault scenario which the stake creates. whatever, it is defined as a structur/building to use the earth stake scenario.

i hope this makes sense. i'm sure there are details and exceptions of a non-standard nature to this general summary, but just always think "how would it fail the safest, and cover the most asses if it does?"  and it gets tons clearer regarding what needs to be done pre-emptively.


clockwork green

What about having no stage or a simple wooden one?
"there's too many blanks in your analogies"

cat shepard

#3
If you are plugging power cords directly into the provided GFI circuits on the generator then you do not need a grounding stake it appears. If you are using an external breaker box which I have to do most of the time (but not the time gospel lips fried!!!) you need to stake it!!!

• The generator supplies only equipment
mounted on the generator and/or cordand
plug-connected equipment through
receptacles mounted on the generator,
§ 1926.404(f)(3)(i)(A), and
• The noncurrent-carrying metal parts of
equipment (such as the fuel tank, the internal
combustion engine, and the generator's
housing) are bonded to the generator
frame, and the equipment grounding conductor
terminals (of the power receptacles
that are a part of [mounted on] the generator)
are bonded to the generator frame,
§ 1926.404(f)(3)(i)(B).
Thus, rather than connect to a grounding
electrode system, such as a driven ground
rod, the generator's frame replaces the
grounding electrode.
If these conditions do not exist, then a
grounding electrode, such as a ground rod,
is required.

I had it put to me like this yesterday. You  aren't holding drills and power tools up to your moist lips while standing in a stage puddle of beer or something.

jibberish

so it sounds like your deal is an extended electrical network which forgoes the scenario's 1 or 2.  it all jives.

Discö Rice

Somebody's gonna eat my pussy or I'm gonna cut your fucking throat.

jibberish

no, the other thread had too much conflict. this is the summary and how all the perspectives in the big thread actually do fit together around those osha codes.   you should try to understand all this. you may be in a generator powered situation where all the details arent quite squared away, but you can see the issue, or if it all looks good.

Ayek

Shit gets messy when it comes to deals like this, which is probably why generator manuals steer clear. You want to avoid the whole "if I hold this or stand here and touch that, I get shocked". I suck at trying to explain things. Also, 'metal structure' could be anything like a speaker stand or lighting stand or whatever. Shoot, I gotta go to work