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Generator set up ideas wanted
Murf,
I will ask for a better explanation from my electrician,
and try to repeat it here.
Ann brush, sorry about the selfish remark, our small town
had a tragic fire last Fri. night where a two year old boy
died of smoke inhalation.It was a 3 apt. bldg.
Lot's of articles in the paper everyday, and a lot of acusations flying. Smoke alarms?,known faulty wiring,?
I know I went home and checked all my smokes !
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Generator set up ideas wanted
Murf
I just called him to ask, I want to make sure I'm doing it
right as you sound very familiar with it.
He did not give me a technical explanation,but said you are right it does not break the neutral(3rd leg)? He said none of them do? Even the new transfer throw switch next to the meter, nor do the automatic ones. He said( the one I spoke of in the panel) is approved by UL and meets the national code.
How can this be? We can still backfeed and zap someone?
Wish I understood it better, electrical moron.
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Generator set up ideas wanted
Ann, with all due respect, I THINK you misread the statements & information.
"If you install a single phase TS, remember that the neutral to ground bond needs to be isolated just as a subpanel would be.
--------------------
Pierre Belarge
Instructor & Industry Advocate"
Notice the word "isolated" ? What he is saying is that if you do NOT have a three pole TS, you need to isolate the neutral to ground bond. In other words, with a single phase TS, you must mechanically break the neutral / ground bond, a neutral switching TS does it for you.
Grinder, the problem all arises from the old "go with what works for the biggest percentage" theory. In a purely electrical engineering manner of thinking, bonding the neutral to the ground (earth) is dumb. However, if they didn't they would still have problems, just different problems that's all.
The problem is a little too complex to put easily into crayon. Google search "stray voltage" or "transient voltage" and do a little reading, if you don't get a headache I guarantee you will at least sleep well tonite.
Best of luck.
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Generator set up ideas wanted
Murf, in my citation which you quoted:
"If you install a single phase TS, remember that the neutral to ground bond needs to be isolated just as a subpanel would be.
--------------------
Pierre Belarge
Instructor & Industry Advocate"
Pierre is refering to the neutral to ground bond INSIDE the generator - not as you suggest the neutral to ground bond at service entrance. He compares the neutral to ground bond INSIDE the generator as being similar to a neutral to ground bond in a sub panel.
So with all due respect your comment:
"Notice the word "isolated" ? What he is saying is that if you do NOT have a three pole TS, you need to isolate the neutral to ground bond. In other words, with a single phase TS, you must mechanically break the neutral / ground bond, a neutral switching TS does it for you."
where you mistakenly interpret the neutral to ground bond as that located at the service entrance is not correct.
There are 2 basic generator grounding wiring types:
1) Generator with floating neutral - neutral not bonded to ground at or inside the generator.
2) Generator with bonded neutral.
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Grinder and of course other interested readers:
Here is a very well written article that discusses this very issue and provides very comprehensive easy to understand wiring diagrams. They show when a transfer switch that switches neutral is needed and when one that does not (as Grinders electritian has indicated) it required.
Link:
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Grinder, earlier this year I purchased the 18HP Honda 8000 watt portable generator from Northerntools. I'm very pleased with it with the exception that I have not been able to manually start it as backup (it starts fine using electric start). Cost me $1,900 I believe.
I liked the 6500 watt portable diesel but it didn't have enough watts to drive all the appliances my wife wanted to support. I would rather have 20 gallons of diesel hanging around rather than 20 gallons of gasoline.
I spent a lot of time considering more expensive options, but as AnnBrush suggests, you get into big money very quickly. If you use the propane standby units you need to purchase or rent propane tanks, use fuel on test cycles etc. Here you are talking $3,000+. If you go diesel standby you are talking $5,000-$10,000.
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"crayon" goog one,fine tip marker might work.
So, is the double breaker in my square "D" panel OK or
am I going to hurt a lineman or burn down my house?
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Grinder - it depends on your generator. Look at the specific wiring for the generator you have (will buy). If it is floating neutral - use a double pole transfer switch (two hot lines) but leave neutral connected at the service entrance. If neutral is bonded to the frame at the generator use a transfer switch that disconnects the neutral. In my experience it is cheaper (much) to isolate the neutral to ground connection in the generator than is is to buy the transfer switch that switches neutral but you will have to reconnect it if you use the generator for anything else but powering the house. Print off the reference I posted above and identify what setup (8 different scenarios are provided) you have and apply the correct connections. Get an electritian to verify you have the correct set-up.
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Ann, I must again disagree, you are co-mingling TWO DIFFERENT hazards and coming up with one answer.
What you are talking about is ground fault.
If you have a generator with no ground, and then open the ground neutral bond at the service entrance, you will have an electrified house with no ground at all! Further in fact, you will have disabled all the GFCI circuits, so now you have the very real possibility that someone is holding a defective electrical appliance in the bathroom, and reach out to turn on the water. Guess what? That person just became a path to ground via the water pipe!!!!
In this situation, yes, leaving the neutral / ground bond is mandatory, if only for the safety of people in the house. But it will potentially still be very dangerous somewhere else.
What I am talking about is Transient Voltage.
No matter what the ground system is in your generator, the neutral & ground wires are bonded together at the electrical service entrance to your house, if you then open the two load lines and power up a generator, you ARE creating a voltage potential in the neutral / ground line. PERIOD.
It does not matter where the ground / neutral bond is made, generator or panel, it is still there, and the genset will still create voltage potential somewhere down the grid.
Ann, can you explain to me why you say I am wrong in this?
Grinder, burn down the house, no, definitely not, a linesman, possibly could get a jolt, anything between "Oh sh#$" and fry, no way to tell until it happens. Some places allow the use of something called a "gang switch", basically a big handle which activates 3 separate switches simultaneously. Before this can be used however, it is critical that a second ground rod be installed so that the wiring in the house remains grounded after the neutral / ground bond is broken by the gang switch.
Best of luck.
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Murf and others still interested, I have to post a rebuttal to Murf's last post. This will be my last on this subject.
Read and understand the article I posted. There are situations (it depends on the wiring of the generator) where the transfer switch is required NOT to switch the neutral. In these cases the neutral remains connected to the utility. Not only is this safe it is required by code.
All this talk of backfeeding the utility (and presumably killing a lineman) is really not relevant here. Backfeeding is not possible even if neutral remains connected in the transfer switch (as is sometimes required) if the hot lines are switched (as required in all situations) and neutral is grounded at one location only (service entrance). As a minor asside on this issue I challenge any readers out there to demonstrate how a circuit could be completed that could injure or kill a lineman when the neutral line remains connected to the utility and connections are made according to code.
The main point here is that the decision to switch the neutral in the transfer switch is dictated by how the generator is wired. It is over this point that Murf and I disagree, I worry that Murf's prominent and regarded stauts on this forum (and deservedly so!) will lead readers to conclude that the neutral must be switched in all situations in a transfer switch that switches utliity and generator power. His advice is correct but only in situatins where a bonded neutral generator is used. Grinder's electritian has indicated that in the cases he (she?) is familiar with the neutral remains connected and we can assume that this is safe and would pass inspection. It also implies that there are many floating neutral generator in use out there, mine being one of them.
If you have a floating neutral generator AND you switch the neutral in the transfer switch you have created the scenarios detailed in diagrams 7 and 8.
Quote (from the web link I posted above - BTW it's referencing the CEC or Canadian Electrical Code but the situation in the US is the same for point of this discussion):
"If we try to connect a generator with a floating neutral using a 3-pole transfer mechanism and switch the neutral conductor, Diagrams 7 and 8 show this circuit. In normal conditions (Diagram 7) the load is powered from the utility and the neutral is connected through the generator panel neutral and bonded in the service entrance panel. Everything looks okay.
But in stand-by power mode (Diagram 8) the load is fed from the generator and the generator neutral has been switched. Therefore the neutral bond has been removed from the system. This would be a violation of CEC Rule 10-106 that requires AC systems to be bonded to ground.
These Diagrams show that a 3-pole transfer mechanism switching Line 1, Line 2 and the neutral conductors would result in a circuit that does not comply with the rules of the CEC. In stand-by power mode, a circuit exists in which the system voltage from the generator could float on each phase. In the most extreme case 240Vac would appear on one phase and 0Vac on the second phase, potentially resulting in damage to any 120Vac equipment operated in the home."
End quote.
I cannot put is more straightforward than Schneider Electric has already done. It's a technical issue and hard to understand. It's also the reason that many 2 pole transfer switches are sold and used with confidence and saftey.
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12-07-2005, 14:09 
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