neutral ground bonding - using coach to power the house

[kevink1955]

I think the double bond of the ground and the neutral is less of an issue (as long as both conductors in the bus to house cable are insulated) than the back feeding of a panel via a dryer/welder/hvac outlet and using the main breaker to prevent current flow back to the utility.

The correct way to do it would be a transfer switch before the main house panel.

The ground gets bonded to water and gas services unintentionly many times. If you have an electric water heater it is bonded to the electrical service and also may have a connection to copper water lines. Same thing happens with gas stoves.

I would rather have a double ground to neutral bond than no bond at all, that fault current needs to have a return path to neutral to trip a breaker. Also remember that ground rods provide no function in triping a breaker during a hot to ground fault, it's the ground to neutral bond that handles that.

[Fredward]

Not to intentionally add confusion; living out in the country we have a 30KW 230volt generator powered by the PTO on a tractor. I have a panel in the garage that connects directly to the outlet on the generator. The panel back feeds the main house panel via a 30 amp 230volt breaker. We disconnect the Utility Main and fire up the generator. Aside from accidental reconnection of the Utility Main with the generator running, what is the risk of this set up? I do not ground the generator because I assume it is grounded via the neutral-ground bus in the main panel.
Fred

[robertglines1]

My main concern was hurting the lineman working to restore my power that is why I had Moose a high school   class mate and a lineman for the utility fix me up. I know the way he has it fixed it is as if it were sitting on the ground outside house and totally disconnected from bus. It's his life that is in danger. I don't necessarily trust all the fancy auto switch equipment and think it is simple to manually completely disconnect from bus system.   Got to keep it simple for me. I still haven't figured the computer out. no chance of feed back if there is no connection at all.  won't argue with what it should be by law. More worried about safety. Don't all these automatic switching devices have some control voltage maybe even a half amp that could feed back. Now if we could get all the camp grounds to wire their boxes correctly that would be a milestone. By code they should be- are they?

[kevink1955]

My concern is someone turning the main on while the generator is still connected and powering the main buss. A lesser concern would be pluging in the generator while the main buss still has power, would smoke the generator but at least it would not kill a lineman.

The link below has interlocks for many panels that will only permit 1 breaker (either main or generator) to be on at the same time. Could save a lineman or your generator.


http://www.interlockkit.com/

[Sean]

Other than getting electrocuted, is there a way to test to make sure the system is safe i.e. when the bus generator is separated from the bus and plugged into the house? Can you use a meter to test?

Yes, but it is not simple.

Once the system is fully connected, but not energized, you can disconnect the neutral feeder from the generator at the panel, then test for continuity between the neutral feeder and the ground.  It should read completely open; anything else is dangerous.

Once you have ensured that there is no double-bonding anywhere, reconnect the neutral before energizing the system.

If any of you have ever faced the fact that you will not have power for many days much less the fact that your business's will not have power for possibly 3 weeks you will soon learn that codes are no longer in play. ...

Sorry, but I do not agree.  If someone gets hurt, you will find out very quickly that codes are still very much "in play."

There are safe and legal means of supplying temporary power to structures in emergency situations.  Backfeeding a receptacle is not one of them.

If a panel needs to be powered up from a temporary generator it must be physically disconnected from its normal supply and those supply conductors taped and labeled.  The temporary connection from the generator must be made at the same location. Merely turning off a disconnect switch or main breaker is not sufficient.  It costs nothing but a few minutes of your time and some tape to do this correctly.

And while some breakers may work in both directions (but not all do -- you need to check the specifications) it is not permitted to have the circuit protection for the supply line at its terminus -- circuit protection must be at the originating end.

I will say it again:  This sort of shortcut gets people killed.  Saving a few bucks (versus doing it the safe and legal way) to keep your business running or your house warm is not worth anyone's life.  Learn the proper and safe methods to connect temporary power and do it right every time -- the life you save may be your own.

-Sean
http://OurOdyssey.BlogSpot.com

[Sean]

... Aside from accidental reconnection of the Utility Main with the generator running, what is the risk of this set up? ...

I would suggest that accidental reconnection would be enough risk to avoid doing this.

But since you asked:  There is a reasonable expectation that the main disconnect will cut all power to the panel, and now you have bypassed it in a non-visible, non-obvious way.  Anyone needing to quickly cut power to that panel now has no way to do it, or at least it is not apparent how to do it.  That might include firefighters, paramedics, and other rescuers responding to a situation at your location.

This is precisely the reason that temporary feeds must be immediately recognizable and obvious (as I wrote above), and why permanent transfer arrangements must be clear.  Multiply-fed panels must be so labeled with a clear indication of how to remove all sources feeding them.

Again, it is straightforward to do this right with just a little bit of effort and some extra parts.  Adding a manual transfer switch or an interlocking breaker arrangement such as the one suggested earlier in this thread would make your installation safe and compliant.

-Sean
http://OurOdyssey.BlogSpot.com

[MikeH]

This is a very interesting thread.

We have one of these installed next to our main breaker box in the basement of the house. Generator Panel. It is supposed to be used by plugging a generator into the male 3-prong plug. I think you are supposed to flip the switch before plugging it in. Then we have 4 breakers on it, on the right side of the panel, one for the furnace, one for some outlets, one for some lights, etc. So we would then have power to that area of the house to live in during a storm. The generator is to be outside, and the plug for it is on the outside of the house. We have never used it to the best of my knowledge. This was installed by a professional electrician and inspected by a state inspector.

I think the key to this discussion is to disconnect the bus from the generator? Since I don't have a bus, I obviously am having trouble visualizing how to do this, or what it actually does. If the gen is disconnected from the bus, then the gen is identical to one sitting on the garage floor or the ground next to the house.

Thanks for helping those of us who are electrically challenged.

Mike

P.S. Sean, per your recommendation from Arcadia, I have been working slowly through a basic electricity book in an attempt to better understand your writings. I still have a long way to go. Thank you.

[papatony]

    After all the bull so far Robert is right and the easiest  have an electrician pull a large remote off the main panel with a welding plug .  You have to make sure the main breakers are tripped before pluging in the gen. cord.   Use the KISS system

[Eagle]

We had an ice storm here last January and someone back feed from their generator to their home and an electric company employee that came here to help the local electric company from Ocala Florida was electrocuted because of this.  HAVE A CERTIFIED ELECTRICAN DO THIS AND YOU MAY JUST SAVE A LIFE.

[belfert]

I did this the easy, but expensive, way.  I installed a permanent standby generator when my house was built.  I have an automatic transfer switch and a seperate subpanel in the house for stuff powered by the generator.  I went to all this expense and only two power outages in 9 years.  I pump a ton of water out of my basement and I didn't want a flooded basement with no power.

My generator does burn natural gas.  I figure if we have a disaster that knocks out both natural gas and electric I will have bigger things to worry about than electricity for my house.  I would still have the option of running extension cords to my bus generator.

I did not have an RV with a generator when I installed the standby generator.

[Chopper Scott]

That's why I stated that my breaker panel was one that only I understood Sean. There was no chance of backfeeding into the main power system. I am sure it wouldn't meet codes. I thought we were talking about grounds?

[bevans6]

I was wondering when someone would mention the right way to do this.  There are easily available and not all that stupidly expensive automatic transfer switches designed to do exactly what is being discussed - connect a generator to a house for emergency power.  In the big picture, not all that much fuss. 

In my current house, I put the generator on the porch or the back deck, and run a big extension cord in through the basement window.  I plug in whatever I need at the time.  My new house is farther out in the country, and has a manual setup for generators.  Professionally installed but I am almost positive there are code issues with it.  One of my first jobs when i get out there this summer is to trace it all out,, figure out what the electrician did, and get a licensed electrician in to fix it.

Brian

[Ed Brenner]

My solution is easy, fire up the generator live in the bus until power is back on!
It sits on a concrete pad beside shop full hook up to water and sewer,heat and air, empty out house frig if needed.
Problem solved!!
ED

[artvonne]

  I continue to amazed at how three simple wires and a ground can be so confusing, especially ground and neutral bonding.

  I have to say that this very subject is very timely, something ive intended to figure out before now. But after reading all this I see just how little I know about the subject and that I need more study.

   

 

[Seayfam]

Now that the smoke has settled and everyone has given their thoughts, I'll give my last thoughts.
I have wired approximately 50 houses and I come from a family of electricians, my oldest boy is going through the (IBEW) as we speak. However I am new on this board, so nobody should take my word for anything. Butt "Sean" is our residential electrician here... He is not going to steer any of us in the wrong direction!!

I myself and probably Sean could never live with the idea of telling someone to do something that is illegal and unsafe. If something ever happened, It would be on us.
There is a LEGAL AND SAFE way of doing this. And there is many other ways of doing this, that is quick and will work, but illegal and potentially deadly.

I do have one disagreement on one thing, If you have a house that has the neutrals and the grounds bonded in the panel. Isolating those neutrals at the panel isn't fullproof.
My experiences are...if a panel has been bonded, then chances are light boxes and switch boxes also have been bonded.

Just my thoughts.

Gary