Ground it to the home system.
I don't know the code details, but there is bare wire, known as "bonding
wire", that code requires run without any splices from the box to the actual
ground.

The important thing is that the ground be redundantly robust.
If there is a ground fault, a hot-to-ground leak in a powered appliance
would raise the potential of the chassis above ground.

Unlike neutral, which code says is to be bonded to ground at only one point,
it is considered good engineering practice to "grid the ground", meaning
multiple connections.

I would run an unspliced length of bonding wire from your box to the
generator.
Additional ground connections, such as a cold-water ground would provide
redundancy.



"Ignoramus24153" wrote in message
...
I am aware that "all generators must be grounded". In the instance of
a standby portable generator like this

http://igor.chudov.com/tmp/onan/Diesel/

how would I ground it? I have two options:

1. Ground it to a new grounding rod (expensive and involves actual
work).

2. Ground it to the home grounding system, such as copper pipes in the
utility room, or even better next to the existing home ground
connection.

Which option here is more legal and more safe?

thanks

i

"Ignoramus24153" wrote in message
...
I am aware that "all generators must be grounded". In the instance of
a standby portable generator like this

http://igor.chudov.com/tmp/onan/Diesel/

how would I ground it? I have two options:

1. Ground it to a new grounding rod (expensive and involves actual
work).

2. Ground it to the home grounding system, such as copper pipes in the
utility room, or even better next to the existing home ground
connection.

Which option here is more legal and more safe?

thanks

i

What does a grounding rod cost???

There are a couple of issues here.
Grounding the generator frame can be done via the Equipment Grounding Conductor
in the cable you connect it with (to the building electrode). Certainly driving
an additional rod when the ground thaws (~$10 plus about $5 worth of hardware)
is a safer approach but it will still have to be bonded back to the house via
the EGC.
The other issue is grounding the neutral. If your transfer equipment switches
the neutral you will need to ground the neutral in the generator.
In most cases the transfer switch only transfers the hot legs so you leave the
neutral isolated in the generator (as most portable generators are shipped).
This grounds the neutral via your main bonding jumper in the service panel.

Greg,
NEC-2002 250.34(C) that requires the neutral to ground bond only if the
generator is a separately derived source. It is only a separately derived
source if the neutral of the sources are switched. See 250.20(D) FPN No1

"Greg" wrote in message
...
There are a couple of issues here.
Grounding the generator frame can be done via the Equipment Grounding
Conductor
in the cable you connect it with (to the building electrode). Certainly
driving
an additional rod when the ground thaws (~$10 plus about $5 worth of
hardware)
is a safer approach but it will still have to be bonded back to the house
via
the EGC.
The other issue is grounding the neutral. If your transfer equipment
switches
the neutral you will need to ground the neutral in the generator.
In most cases the transfer switch only transfers the hot legs so you leave
the
neutral isolated in the generator (as most portable generators are
shipped).
This grounds the neutral via your main bonding jumper in the service
panel.

Depending on how the generator will be used, it may not require a connection
to a grounding electrode system. The NEC states that it you will have
cord-and-plug connected equipment through the receptacles mounted on the
gen, then it doesn't require grounding of the frame. Also if this is the
case, then ensure that the manufacturer has bonded (connected) the neutral
and ground within the generator, as it is a separately derived source.
If the previous is not the case, then you must connect it to a grounding
electrode system. If your are serving a premises with a grounding electrode
system, it must be the same, meaning connect directly to it, or drive a rod
and connect the rod to the existing grounding electrode system. It must be
one grounding system, not isolated.

There are lots of other things to consider like how you will transfer the
loads to the gen, and such, but go carefully.

"Ignoramus24153" wrote in message
...
I am aware that "all generators must be grounded". In the instance of
a standby portable generator like this

http://igor.chudov.com/tmp/onan/Diesel/

how would I ground it? I have two options:

1. Ground it to a new grounding rod (expensive and involves actual
work).

2. Ground it to the home grounding system, such as copper pipes in the
utility room, or even better next to the existing home ground
connection.

Which option here is more legal and more safe?

thanks

i

Ron and I agree. I was just trying to avoid some of the NEC speak that confuses
people. The point is you only want one bonding point between the neutral and
ground and if the transfer equipment doesn't switch neutral that will be the
jumper in your service panel.
(Separately derived source is NEC speak for a system where the neutral is
switched too so it will have separate bonding jumpers that go with the source).
All the frame grounding will be bonded, no matter what the transfer scheme.
Adding another electrode only insures that the ground on the case is more
closely referenced to the dirt under your feet when you are standing there.
Depending on where you live "ground shift" is more or less of a problem.
Here is the sandbox (Florida) I have seen 35 volt transients across 30-40 feet
between buildings.

You are connecting this to your home wiring with a transfer switch that
switches only the hot connection. Is that correct?

I used to have a link to a long article that went into extreme detail and
all that, but have misplaced it. Oh well. Anyhow...

If your generator ground is bonded to generator neutral, you MUST use a
transfer switch that switches both hot and neutral, and you MUST ground the
generator.

If your generator is not bonded (and no normally available generators are
bonded afaik, but your monster...) then you can switch only the hot and MUST
NOT ground the generator.

The article went on for pages about ground loops or somesuch thing (the
neutral being grounded in two different places). So, my suggestion is that
you find out if you can unbond your generator, since you are unlikely to
find a transfer switch to switch both hot and neutral. There is no need to
ground the generator separately, since it's ground is not connected to
anything except the house ground.

Our transfer switch switches both hots and the neutral.

Steve Spence
Dir., Green Trust
http://www.green-trust.org

toller wrote:
You are connecting this to your home wiring with a transfer switch that
switches only the hot connection. Is that correct?

I used to have a link to a long article that went into extreme detail and
all that, but have misplaced it. Oh well. Anyhow...

If your generator ground is bonded to generator neutral, you MUST use a
transfer switch that switches both hot and neutral, and you MUST ground the
generator.

If your generator is not bonded (and no normally available generators are
bonded afaik, but your monster...) then you can switch only the hot and MUST
NOT ground the generator.

The article went on for pages about ground loops or somesuch thing (the
neutral being grounded in two different places). So, my suggestion is that
you find out if you can unbond your generator, since you are unlikely to
find a transfer switch to switch both hot and neutral. There is no need to
ground the generator separately, since it's ground is not connected to
anything except the house ground.

"Steve Spence" wrote in message
...
Our transfer switch switches both hots and the neutral.

Steve Spence
Dir., Green Trust
http://www.green-trust.org

Actually I don't think it does. You change from mains to generator by
turning the mains breaker off and the generator breaker on. The neutral
doesn't have a switch on it that I saw.

No, I don't touch the breaker box. I don't have a separate breaker for
the generator. I'm on inverter until I turn on the generator. the auto
transfer switch then switches the loads from inverter to generator.
There are two relays in the box, one switches the two hots, the other
switches the neutral. when the gen is shut off, it switches the loads
back to inverter.

you can see a picture of it at
http://www.green-trust.org/wiki/inde...olar_PV_System

Steve Spence
Dir., Green Trust
http://www.green-trust.org

toller wrote:
"Steve Spence" wrote in message
...

Our transfer switch switches both hots and the neutral.

Steve Spence
Dir., Green Trust
http://www.green-trust.org


Actually I don't think it does. You change from mains to generator by
turning the mains breaker off and the generator breaker on. The neutral
doesn't have a switch on it that I saw.

Our transfer switch switches both hots and the neutral.
Steve Spence
Dir., Green Trust
http://www.green-trust.org

Actually I don't think it does.

Some "alternate energy" systems are installed as separately derived sources so
they would use transfer equipment that switches the neutral. (perhaps as part
of protection for transients when the system is not connected to the building
ground)
On the other hand most "generator" transfer switches for portable generators
will not switch the neutral since the standard on portable generators is an
isolated ground. If used as a stand alone generator on a job site there is no
advantage to grounding the neutral, in fact it adds a hazard.
Fixed in place, pad mount generators can go either way. They will have a
grounding strap in the wiring compartment that you connect or disconnect,
depending on how you are installing them.
This whole deal can get pretty complicated to describe but the end objective is
to only have one point where ground and neutral is connected, no matter how the
system is switched.
When I am inspecting a complex system I have to draw it out sometimes to sort
out what is going on.

toller wrote:
"Steve Spence" wrote in message
...

Our transfer switch switches both hots and the neutral.

Steve Spence
Dir., Green Trust
http://www.green-trust.org


Actually I don't think it does. You change from mains to generator by
turning the mains breaker off and the generator breaker on. The neutral
doesn't have a switch on it that I saw.



Depends on the design of the transfer switch, I have one outside that is
set up for three phase and has four poles on the switch body.
Dave

In article ,
"Robert Morein" wrote:

Ground it to the home system.
I don't know the code details, but there is bare wire, known as "bonding
wire", that code requires run without any splices from the box to the actual
ground.


That's right you don't know the code details so shouldn't be offering
advice.

On 27 Dec 2004 17:35:58 GMT, Ignoramus24153
wrote:

I am aware that "all generators must be grounded". In the instance of
a standby portable generator like this

http://igor.chudov.com/tmp/onan/Diesel/

how would I ground it? I have two options:

1. Ground it to a new grounding rod (expensive and involves actual
work).

2. Ground it to the home grounding system, such as copper pipes in the
utility room, or even better next to the existing home ground
connection.

Which option here is more legal and more safe?

thanks

i


I believe like any sub-panel, the ground must run back to the main
panel. Sorry that I can't remember what article this is in, maybe
someone else can help with that.

later,

tom @ www.Stuff4Free.biz

On Mon, 27 Dec 2004 18:01:23 -0500,
wrote:

On 27 Dec 2004 17:35:58 GMT, Ignoramus24153
wrote:

I am aware that "all generators must be grounded". In the instance of
a standby portable generator like this

http://igor.chudov.com/tmp/onan/Diesel/

how would I ground it? I have two options:

1. Ground it to a new grounding rod (expensive and involves actual
work).

2. Ground it to the home grounding system, such as copper pipes in the
utility room, or even better next to the existing home ground
connection.

Which option here is more legal and more safe?

thanks

i


I believe like any sub-panel, the ground must run back to the main
panel. Sorry that I can't remember what article this is in, maybe
someone else can help with that.

later,

tom @ www.Stuff4Free.biz

My reading of the pertinent section tells me that if the grounded
conductor is not switched, the generator equipment should be
seperately grounded. The NEC section on seperately derived systems is
not one I've spent a great deal of time with, however. In practice I
have a hard time understanding what problem could arise from
connecting the ground.

Dan

Get a grounding rod and bang it into the earth, then, use the
appropriate connector to fasten 1/4" solid flexible copper to ; fasten
the other end to the generators ground connector. Thats exactly what im
about to do to my portable generator.

Ignoramus24153 wrote:

I am aware that "all generators must be grounded". In the instance of
a standby portable generator like this

http://igor.chudov.com/tmp/onan/Diesel/

how would I ground it? I have two options:

1. Ground it to a new grounding rod (expensive and involves actual
work).

2. Ground it to the home grounding system, such as copper pipes in the
utility room, or even better next to the existing home ground
connection.

Which option here is more legal and more safe?

This may help things..

http://www.cat.com/cda/components/se...language Id=7




--
"Build a man a fire, and he'll be warm for a day.
Set a man on fire, and he'll be warm for the rest of his life."

Terry Pratchett