Temporary Shore Power

[darren paget]

Does this mean that the ground in the panel in the RV be grounded to the chassis
and not to the shore plug? Does the neutral wire have to be connected to shore
power? The generator is self explanatory, as the genset can only be grounded to
the frame. What happens to the ground wire in the shore power plug?

>
> > The neutral and ground do not get TIED together in any residential
> > application,
> > nor in any RV installation I have ever seen. Even though, they get
> 'grounded'
> > to
> > separate bars in the breaker box and appear to be tied together, in some
> > fashion, they are not attached to the same point. Neutral and ground do
> not
> > get
> > tied to the same point.
>
> Daren,
> Actually, in the U.S., the neutral and ground wires (and the system
> grounding electrode) are all tied together at the main entrance box. After
> that point, they must never be interconnected again.
> The explanation I heard was that a very heavy load or short circuit could
> cause enough voltage drop through the neutral wire that said neutral wire
> could be carrying dangerous voltage at some point. Or, the neutral wire
> could fail or become disconnected, again resulting in lethal voltage on the
> neutral. For this reason, a totally separate ground path, one which normally
> carries no load, is provided back to the main entrance. (The bare/green
> wire.)
> At the motorhome, the GENERATOR neutral may be bonded to chassis ground
> IIRC, but the shore power cord neutral MUST NOT be tied to the grounding
> system, nor must the coach neutral wire be grounded whenever the shore power
> is connected.
> HTH.
>
> Rick Staples
> '75 Eleganza
> Louisville, CO

- --
Darren Paget
76 Experimental
Another Fab Day
paget

 

[richard bachert]

Here in the states, it's code to take the ground for the main panel to a 4'
iron rod firmly driven INTO the EARTH. The Europeans, in fact, often call
an electrical "ground" "earth" which, of course, it is.
Dick 75 PB in Atlanta

>I was referring to residential wiring, here in Alberta. I am not too sure
on how
>wiring is done any place else. In a main panel in a house here the ground, or
>bare, wire is connected to a connector bar on one side of the panel. The main
>ground wire of this bar is grounded out somewhere up the line. Buried somewhere
>underground or something like that. The neutral, or white, wire is goes to a
>connector bar on the other side of the panel. The main wire off of this bar
goes
>up the line and is looked after by the utility co. The power feed is
connected to
>either side of your panel as two 110 leads. When you jump across both sides you
>get 220. One side gives you 110. When wiring in your house, the bare ground
wire
>and the white neutral wire do not get connected at the same point and therefore
>are not tied together.
> A 30 amp service has a ground a neutral and a hot wire. A 50 amp service has a
>ground a neutral and two hot wires. Your ground, when hooked up to shore
power is
>made through your plug. The 50 amp service will supply two sides of your panel
>with 110 each. This will give you 220, if the service is 220, when you jump
across
>both sides. The 30 amp service will give you 110 to your panel. This can be
split
>in two, the way the Onan is done, to feed both sides but when you jump
across you
>will not have 220. The 40 or 50 amp service will allow you to run two AC's
and the
>30 will let you run 1.
>

>
>> In a message dated 7/1/99 1:31:43 PM Eastern Daylight Time,

>>
>>
>>
>> Subject: What does an electrical service look like?
>> There are logically four wires involved with supplying the
>> main panel with power. Three of them will come from the utility
>> pole, and a fourth (bare) wire comes from elsewhere.
>> The bare wire is connected to one or more long metal bars pounded
>> into the ground, or to a wire buried in the foundation,
>> One of the other wires will be white (or black with white or
>> yellow stripes, or sometimes simply black). It is the neutral wire.
>> It is connected to the "centre tap" (CEC; "center tap" in the
>> NEC ;-) of the distribution transformer supplying the power. It
>> is connected to the grounding conductor in only one place (often
>> inside the panel). The neutral and ground should not be connected
>> anywhere else.
>> The other two wires will usually be black, and are the "hot"
>> wires. They are attached to the distribution transformer as well.
>> The two black wires are 180 degrees out of phase with each
>> other. This means if you connect something to both hot wires,
>> the voltage will be 220 volts. If you connect something to the
>> white and either of the two blacks you will get 110V.
>> Some panels seem to only have three wires coming into them.
>> This is either because the neutral and ground are connected
>> together at a different point (eg: the meter or pole) and one
>> wire is doing dual-duty as both neutral and ground, or in some
>> rare occasions, the service has only one hot wire (110V only
>> service).
>>
>> My GMC is still at Buskirks waiting for the engine replacement to be finished
>> so I do not have the GMC manual to look at.but since we all don't drive a
>> ground rod into the earth when we park our motorhomes, I expect that the box
>> in the motorhome may just put the green wire to chassis ground but the
>> neutral wire would not go to ground. This can be checked on the GMC wiring
>> diagram. This would only apply to the 50 amp service. The 30 amp (Royales?)
>> would not have the ground wire.
>>
>> Emery Stora
>> 77 Kingsley
>> Santa Fe, NM
>
>--
> Darren Paget
> 76 Experimental
> Another Fab Day
> paget
>
>
>

 

[webteam]

John,

Is this the information you were looking for about the floating ground? You
were right it was from Richard Waters.

HTH,

RTR

From: Richard Waters
Subject: Re: GMC: Temporary Shore Power

Please refer to page 134-135 of RV Electrical Systems by Bill and Jan
Moeller
which states "In residential wiring, the neutral conductor is always
connected to
the grounding conductor at the service panel." Then they go on to say "An
RV is
said to be electrically "floating" because it is insulated from the earth,
or
ground, by its tires, which have the only contact with the earth (metal
jacks do
not provide an adequate ground). Therefore, the neutral conductor is also
floated
or isolated from all contact with the chassis or other metal parts of the
RV.
Only the grounding conductor is bonded to the RV. If the neutral conductor
were
connected to the chassis and metal parts, any metal on the RV would be
electrically charged, shocking anyone who touched it while current was
flowing
throughout the system."

Richard Waters '76 PB, Troy, MI
- - ----

>
>> Richard Waters...
>>
>> If you are still there... I think I recall you posted an excellent write
>> up on the Floating Ground System in the GMC. (I can't find my copy) If
>> I am correct, and you can easily do so, would you repost, under this
>> subject? If you can't find it easily, I'm sure someone has a copy that
>> they can find.
>>
>> It would be easy just to forward another copy, but I don't think our
>> Mailinglists.org will pass forwarded messages to cut down on annoyance
>> forwarding.
>>
>> Regards,
>> John

 

[john dolan]

RTR...

Thanks, I felt that was an excellent contribution in terms of style and
content; he quoted factual research and/or considered opinion and
included the reference. Maybe Richard is one of those guys that insists
on sitting at a small table in the corner, until every is seated and then
he is forced to move up to the head table. (watch him say this was on
RVs in general, not on the GMC)

>Is this the information you were looking for about the floating ground?
>You were right it was from Richard Waters.

>From: Richard Waters
>Subject: Re: GMC: Temporary Shore Power

>Please refer to page 134-135 of RV Electrical Systems by Bill and Jan
>Moeller. ~ where they state...
Regards,
John

- --
"I do whatever my Rice Krispies tell me to..."
John said, from inside a 1974 Glacier on the
Potomac, just north of the White House.