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Ontario lakeside
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# Posted: 27 Nov 2016 22:11
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We also haven't grounded our genny. technically its better to ground it, in practice not a big issue.
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bldginsp
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# Posted: 27 Nov 2016 22:38 - Edited by: bldginsp
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Quoting: deercula Can someone please explain in simple terms what the dangers are by using it not grounded. I asked an electrician a while ago and he said if I was powering fairly new equipment, and not in standing water, I would not have to worry. Did he know what he was talking about?
Let's say that you have a generator outside sitting up on a wooden platform, off the earth, no connection to earth. Or, let's say your generator is sitting on the earth with rubber wheels, like mine. The generator is running and operating whatever inside the house. Then, one of the pieces of equipment in the house gets a ground fault. A ground fault is when hot electricity gets out of the simple circuit we made for it- hot to equipment, neutral back to source, or, hot to equipment, hot back to source (240). Anyway the insulation rubs off the hot wire, and the bare wire touches the frame of the equipment. Now the frame of the equipment (washing machine, hair dryer, light fixture, whatever) is hot- energized with electricity. Now what is supposed to happen is that the frame is grounded- a green wire is attached to the frame. The electricity in the frame wants to return to it's source. It can do so in the green ground wire. When this happens, usually, theoretically, the amperage spikes and the circuit breaker on the hot wire trips, removing the danger.
But- things don't always happen the way they s'posed to. Lets say the frayed wire that is energizing the frame is just barely contacting it- or contacting it intermittently. Not enough amperage goes to the ground wire to trip the breaker. Or, the ground wire is disconnected, or there isn't one to begin with. End result is that the frame of the equipment stays energized. As long as it is energized, it is looking for a path back to its source. The earth is one such path, but not a very good one, usually. It has high resistance. But if that is the only path available, the electricity will try to take it. If the power in the energized equipment frame can find a path to the frame of the generator, the circuit is complete. This is because with MOST generators the frame, ground, and neutral are all bonded together, so the frame provides a path to the neutral.
OK, so the energized washing machine frame is in contact with the earth only 30 feet from the generator. But the current cant jump from the earth to the generator frame because it is sitting on rubber wheels. Then it rains a bit and the earth is wet. Then you walk over the generator to check the gas, and you touch the generator frame. The fault current in the washing machine now has a path back to neutral- directly through you. Because the earth is wet, there is little resistance and the amperage spikes as it passes through your body.
However, if the generator is grounded with a solid connection to earth, you won't get shocked. The current already has a path back to neutral. It may not be a high enough amperage path to trip the breaker, but because the generator is connected to earth it must have the same electrical potential as the earth. The two, theoretically, can't be different. Since both the earth and the generator frame have the same potential, the electricity doesn't go from your shoes on the ground to your fingers to the generator frame. But with no such ground rod, there is a significant difference in potential between the earth and the generator frame. In which case, when you touch it while standing on the ground, you are the sole path back to neutral. Now, if you hung from a helicopter and touched the frame, you wouldn't get shocked, but, well, you see the point.
If the electricity does not pass through your heart, you'll live to post another day. If it does, with as little as 4 milliamperes, it will stop your heart. Unless someone is there with a defibrillator or doing CPR, you'll be brain dead in 9 minutes.
Equipment with no ground plug is double insulated, and so allowed to have no ground. If it fails the double insulation should keep you safe, unless your drop your double insulated hair dryer into the tub with you while taking a bath. Any equipment with a metal frame will have a ground plug and should be used.
The scenario I described depends on a lot of things all happening at once- a cluster fludge, so to speak, and may seem like a remote possibility. But stranger things have happened and when it does someone gets shocked, and either dies or doesn't, depending on which hand they touch the hot stuff with. Your left arm is closer to your heart, so current through it is more likely to hit your heart. This is why inspectors put their left hand in their rear pocket when looking in electrical panels installed by someone else.
But if the frame of the generator is not bonded to the neutral, touching the frame does not complete a path for the fault current. But, if there is no connection between ground and neutral (somewhere near the source) then circuit breakers won't trip in fault current when there is a good ground path back to the source. So, the method we use to clear ground faults for the sake of safety can, in some circumstances, create another equally dangerous situation- if, that is, the power source has no connection to earth.
The grounding we do on equipment with a ground wire serves a different purpose than the grounding we do of equipment by connecting to earth. That is a major source of confusion for the inexperienced. Next code cycle, ground wires to equipment will be called equipment bonding conductors instead of equipment grounding conductors, but the wire from your service to your ground rod, Ufer and water pipe will still be called a grounding electrode conductor.
Sorry for the long post, hope it makes sense. Don't mess with electricity, or it will mess with you. It's a force of nature, and we think we are smart enough to contain it.
Please drive a ground rod, Julie. It's not that hard. And always confirm that the ground and neutral are bonded to the frame of your generator, unless you are using a transfer switch and know what you are doing.
Goodnight.
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groingo
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# Posted: 28 Nov 2016 11:11
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In a nutshell, provided you are not wet or standing in water there should be no issues, but just to be sure I did ground my system very simply using 1/8 thick copper wire attached to the geny then ran it outside in a six foot deep hole loosely coiled, backfilled and done....never been shocked or buzzed in any weather.
Also, to improve effectiveness of ground, put it in moist soil which improves conduction.
Bottom line, be sure connectors and outlets are in good shape, be dry when you fiddle with electrics and no worries.
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bldginsp
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# Posted: 28 Nov 2016 14:01
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I'd put the nutshell a little differently groingo.
-Since it is always possible for fault current to find its way to earth, even when not wet, connecting the generator to earth is the only way to prevent getting shocked by touching the frame.
-If the generator is the sole source of power, be sure ground, neutral and frame are bonded at the generator.
-Make sure all circuits have a breaker behind them, and that all circuits have a ground wire that makes its way to the generator ground.
And then you have the basic safety systems used in modern electrical installs.
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NorthRick
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# Posted: 28 Nov 2016 16:22
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We have an electric fence at our cabin. It uses the ground to complete the circuit to give you (or a bear) a shock when you touch a hot wire. The ground doesn't have to be wet for that to happen.
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Nate R
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# Posted: 28 Nov 2016 16:42
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Yes, but electric fences are thousands of volts, not a couple hundred. Makes it easier for the charge to complete the path.
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bldginsp
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# Posted: 28 Nov 2016 17:36
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Electric fences are around 8,000 volts, but only 100 or so milliamps. It is an odd sort of circumstances that will create the conditions for a shock thru earth with a generator, but it will have 15, 20 or more amps to deliver. Can be lethal.
It takes only 4 milliamps to stop your heart, so I wonder why electric fences don't kill animals or people. Maybe that 100 milliamps is greatly reduced by the impedance of the earth, which is a poor conductor. I don't know.
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silverwaterlady
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# Posted: 28 Nov 2016 18:57
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TY bldginsp for explaining this to me. Can put up a diagram or explain exactly how a gene like a Honda 3000 on a concrete pad with a metal roof open on all sides can be properly grounded.
The ground in our camp area is rocky. So it's quite a chore to dig. Idk if that is what we would need to do?
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drb777
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# Posted: 28 Nov 2016 19:51
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Virtually all gen-sets have a ground connection, usually marked as such. As shown here, one can share an existing ground rod. Years ago, many would attach to a steel water pipe, not really such a good idea since it could actually cause other problems and may not be well connected to ground.
gen set, natural gas fuel
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bldginsp
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# Posted: 28 Nov 2016 21:04 - Edited by: bldginsp
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Silverwaterlady- your cabin may already have a ground rod, or other electrode, such as a metal water pipe underground or a Ufer ground, which is a connection to rebar in your foundation. A lightning rod always goes to ground rods as well. If you have any of these, run a #6 copper wire from it to the generator. As drb777 said, the generator should have a connection point.
If you don't have any metal already in the earth, and you have very rocky soil it will be difficult. You want to dig as deep as you can to get to soil that stays moist throughout the year. Also, you can drive multiple ground rods at least ten feet from each other and connect them all. Maybe they all will be only 3-4 feet deep but you have more than one.
If you do have other electrodes, and you drive one for the generator, connect it to the others as well. The Electrical Code says to connect to ALL things that can function as electrodes in the earth. This is for two reasons- to lead lightning to earth and hopefully do little damage in the house, and for the reason we are discussing here. The better your connection to the earth the safer you will be.
As mentioned by someone above, a ground rod is actually one of the worst grounding electrodes, only because it is so small. A forty foot copper water pipe under ground is probably much better, as is a connection to the rebar in a full perimeter foundation, or in deep piers. When soil is dry, conductivity goes down so the more electrode area you have exposed to the earth the better connection you will have. I think creeky mentioned buried plates which works well because a plate has a large area of exposure to the soil. The one big advantage to a ground rod is that it goes deeper than most of the others, if you can get it down there.
So, I thought, the 400 foot deep steel well casing must make an excellent ground rod! Indeed it would, but if lightning hits your well casing it will certainly fry your pump. The well cap should be bonded to the ground wire run with the pump conductors, but I wouldn't connect the casing directly to the rest of the electrode system unless you have a hand pump only, or a jet pump with no direct conductive connection to the metal casing, if this is possible.
Hope we are not too far off topic here Julie. Seems like we kind of left you behind somewhere... sorry....
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silverwaterlady
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# Posted: 29 Nov 2016 01:21
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TY both. 
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Timmy boy
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# Posted: 4 Feb 2017 17:06
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To Silver Water Lady. I have a question about applying for a building permit. Are you by chance on Manitoulin Island in the town of Silver Water on Manitoulin Island and applied to the Manitoulin Planning board. The reason is because I am there and want to know the how hard the process was to get a permit to build? Thanks
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toyota_mdt_tech
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# Posted: 4 Feb 2017 19:57
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Quoting: bldginsp -Since it is always possible for fault current to find its way to earth, even when not wet, connecting the generator to earth is the only way to prevent getting shocked by touching the frame.
Just thinking out loud here. Most generators have no neutrals, so could a person wire in a GFCI outlet in line feeding the cabin etc, even without a ground and as soon as it sees current going elsewhere (I think specs is like 1/40th of a second) would it trip the GFCI? Would a GCFI even work without a ground and/or neutral? I suspect it will.
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MtnDon
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# Posted: 4 Feb 2017 20:58 - Edited by: MtnDon
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A GFCI will operate correctly without a ground connection. They measure the current difference between the neutral and the hot wires. A GFCI without a ground wire will test correctly using the built in test button, BUT they will fail is tested with an external tester like the electrical inspectors carry. However if/when the inspector checks that they is no ground they have to pass it if the built in test button works ok. An older home with original wire will not have a ground wire.
Not sure about your statement "most generators have no neutrals". For 120 VAC to work there has to be a hot and a neutral. There are two types of generators, those with a bonded neutral and those with a floating neutral... is that what you were leading to?
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bldginsp
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# Posted: 4 Feb 2017 21:43
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GFCIs are always a good idea, in any circuit, and the elec code will probably eventually require them and AFCIs in all circuits. But they don't guard against shorts and overloads, so standard breakers or fuses are still necessary.
I was once told that in Israel they have no inspections of electrical systems, but all electrical services have a big GFCI on the main disconnect. Anything goes out in the house, whole thing goes down. Draconian, but effective.
My understanding is that there are some generators and inverters that have no neutral- they produce two 60 volt hots to deliver 120 across the two. This is entirely different than the issue of whether the neutral is bonded to ground or not.
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toyota_mdt_tech
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# Posted: 4 Feb 2017 22:21
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Quoting: MtnDon "most generators have no neutrals". For 120 VAC to work there has to be a hot and a neutral. There are two types of generators, those with a bonded neutral and those with a floating neutral... is that what you were leading to?
No, there is no neutral at all, many generators have no neutral. Like bldg insp said, its 60VAC from each leg, so across it, (peak voltage is 60V and peak to peak is 120VAC. My EU2000i is one example of this. Visualize your house, measure across from L1 and L2, you have 240VAC, now think of each leg in a duplex plug in a generator as L1 and L2, but it reads 120VAC.
Now looking at the generator, it does use a 3 phase WYE wound stator, but neutral (tie point in the middle) is not used. Those 3 phases goes into the inverter and you get 120VAC out with no neutral. Of course, there is no ground in the duplex plug, its just bonded with the chassis.
Go to: http://cdn.powerequipment.honda.com/pe/pdf/manuals/31Z07610.pdf
Then on page 58 of the PDF file
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MtnDon
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# Posted: 4 Feb 2017 22:28 - Edited by: MtnDon
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Quoting: bldginsp inverters that have no neutral- they produce two 60 volt hots to deliver 120 across the two
Pretty sure it is that some cheapo, modified sine (square) wave inverters do a trick which generates a 120 volt AC output by having the two AC output terminals alternate between +60 and -60. That makes it appear to produce 120 VAC to a meter or whatever. Only applicable to MSW inverters, not generators.
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SCSJeff
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# Posted: 12 Oct 2017 14:21
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coming to the party very late here, but wondering the same thing for my setup...
I have a neutral/ground bond in my panel and the panel is grounded via a grounding rod. Panel is fed by my portable generator (does NOT have neutral and ground bonded) . I currently do NOT have the generator grounded via it's grounding bolt. I have GFCI receptacles in my kitchen that do work. However, they won't trip when using my tester. (At the moment, I can't remember if the test buttons work correctly or not, but I think they do)
However, I'm confused by the statements that "most" generators are neutral/ground bonded??? I know many of the Honda's are. But, every sub $600 portable generator I've used from the big box stores are not bonded.
So, if my generator is not bonded, should I ground it anyway (even if my panel is already grounded)? If I do ground it, would that allow the GFCI's to test properly?
Thanks,
Jeff
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toyota_mdt_tech
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# Posted: 12 Oct 2017 15:01 - Edited by: toyota_mdt_tech
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I just seen the Honda EU7000is is now equipped with a GFCI plug and I see the Honda makes an EB2000is with GFCI plug.
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Bushwhacked
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# Posted: 13 Oct 2017 02:00
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Also I just saw today Home Depot cut prices on the Honda generators. Just FYI
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toyota_mdt_tech
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# Posted: 13 Oct 2017 21:25
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Quoting: Bushwhacked Also I just saw today Home Depot cut prices on the Honda generators. Just FYI
I just checked, you are right. I see the EU2000i is shown for $899, $999 for the EU2000i companion. Super price. I suspect all retailers will also sell them for that price too. I suspect mfg lowered the wholesale price of them.
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