electrical problems

[mbulriss]

Hi Juergen,

+1 on what Don said.

The big rig/MH 50 A service is actually two split phase 110V 50A legs
(the two legs in your main box) or 220V 50A across the two hot legs.

> The way I read your post, I could survive or not even get a 250
> surge even if the bare wire is not making contact. I cannot say
> for sure, but I also will never try it.

That is how, and here is how, I understand it. The neutral or white
wire is the differential or 'return' flow. The green is ground for
safety. If I have to lose one, I am much safer to have lost the
neutral rather than the safety ground. As I understand it, when you
lose the neutral on the RV wiring configuration, any return
differential is now going down the other the hot line in the case of
imbalance. If you lose the safety ground and any of the hot wires
touches metal, you potentially fry stuff, and/or you can become the
ground when stepping on/off the bus. Not a good thing, for sure.
That's why I said if I have to lose one, I was happy it was the
neutral - less potential risk to me personally.

> I never try to put or pull the plug UNLESS the CBs are
> OFF.

Excellent idea, which everyone should also follow (always ticks me off
when I come to a pedestal that still has the CB on after the last
person left). However, when pulling out those sometime slippery 50A
plugs, I know we probably all often also grab the wire below the plug
to help 'wiggle' the plug out. The constant handing and wiggling
torques the wire bundle which eventually loosened my neutral, if it
had ever been tightened properly in the first place. That's why
everyone should check their plugs for tight wiring connections.
(Thinking about it now, my old plug also did not have any strain
relief collar around the wires behind the plug to help reduce the
wiggling wires in the plug.)

FWIW. In any event, I do not like working on 30/50A wiring, but I
enjoy the end results of using it.

Off to the Bird to maybe go somewhere.... everyone have a good weekend.

Mike Bulriss
1991 WB40 "Texas Minivan"
San Antonio, TX

--- In WanderlodgeForum@yahoogroups.com, "Don Bradner"
wrote:
>
> Juertgen, you can only get 240V across the two hot wires. when that
happens, the neutral (white) is not carrying any load at all.
>
> The neutral line carries only the differential. If you have 50 amps
of 120 in use on one leg, and 50 amps on the other leg, again the
neutral is not carrying any load.
>
> If one leg is drawing 30 amps and the other 50, the neutral will
have 20 amps of current present.
>
> The three statements above are true because the two hot legs are
opposite phase. When viewed as a sine wave, when one is on the upside
of the cycle the other is on the downside of the cycle.
>
> The separate 4th wire (green or bare) is ground. It is not intended
to carry any current, and is a protective line only.
>
> In a home system the common and ground are bonded, but under RV code
they are not bonded, so they are not at all the same thing.
>
> On 8/30/2008 at 7:21 AM Juergen wrote:
>
> >Mike
> >Here is where I am at a loss as to why you get 250 V when only one wire
> >either green or bare makes contact. I know that 2 hot and one
ground =250V
> >I do not understand why the bare wire contact then allows two 110
V. And
> >like I said before, I never try to put or pull the plug UNLESS the
CBs are
> >OFF. The way I read your post, I could survive or not even get a
250 surge
> >even if the bare wire is not making contact. I cannot say for sure,
but I
> >also will never try it. Electric system is too costly. All I know
is 250 V
> >will really brighten up your lights for a brief moment and fry all the
> >other components. Been there done that (in my house.)
> >Juertgen in PA
> >1991 WLSP36
>