First Post - Wiring 78 Royals Neutral Ground short trips GFI

[aaron bush]

Hi everyone,

I bought my Royale in early March, made it to Shawnee (it was just down the road.) I've been working on my coach ('78 rear dinette Royale) as a I can,
I've read a lot of posts since then.
I'm posting this because

1. I haven't been able to find the wiring set-up on my coach anywhere else, and I do think it's original
2. Thought someone might have suggestions for modifications to my proposed solutions to my wiring problems
3. Thought I should say hello.

The problem.

My coach trips a GFi shore power outlet when I plug it in. Not too uncommon it seems, so I traced the ground/neutral short down to ...

the onan. The generator grounds to itself - news to me but it seems like whoever originally wired the coach should've known that. :-/

The wiring in my coach is similar to, but not the same as.

http://www.bdub.net/wirediagrams/1977_Coachmen_26RB_Electrical_and_Plumbing_Drawings.pdf

I have sketched out the components and wiring and of my coach.

http://www.gmcmhphotos.com/photos/data/7081/Aaron_Coachmen_1978_Original_House_Wiring.pdf

The problem is that the main breaker for the onan is a single pole breaker, so it doesn't disconnect the neutral wire even when it's off. That
combined with "Junction box 3" gives me a ground/neutral short that trips the GFI protected outlet I plug into for shore power.

I've drawn a second set-up that I think resolves the issue, by putting in an 50 Amp auto transfer-switch and getting rid of some of the original
equipment, which greatly simplifies the house wiring.

http://www.gmcmhphotos.com/photos/data/7081/Aaron_Coachmen_NEW_House_Wiring1.pdf

This is the simplest solution I can come up with, I really only have to buy the auto transfer-switch, the rest is tearing out things I don't need. And
wiring one plug onto the rear AC wire. The PD 9260 isn't essential for the problem I'm having, but as long as I'm in there, I'm going to get rid of
the old converter and upgrade to a newer battery charger.

cheers,

Aaron

--
78 Royale, rear dinette

 

[LQQKatJon]

You could get rid of the transfer switch entirely??

Most gmc's do not have a transfer switch, the onan wires up to a female outlet, and you either plug coach into that outlet for generator use,

Or it plugs directly into shore power. Where the onan is now completly separate from coach wiring.

Transfer switch could be nice, but I personally dont think it is all that nessiary.
--
Jon Roche
75 palm beach
St. Cloud, MN
http://lqqkatjon.blogspot.com/

 

[Gene Fisher]

Me three

> You could get rid of the transfer switch entirely??
>
> Most gmc's do not have a transfer switch, the onan wires up to a female
> outlet, and you either plug coach into that outlet for generator use,
>
> Or it plugs directly into shore power. Where the onan is now completly
> separate from coach wiring.
>
> Transfer switch could be nice, but I personally dont think it is all that
> nessiary.
> --
> Jon Roche
> 75 palm beach
> St. Cloud, MN
> http://lqqkatjon.blogspot.com/
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://bdub.net/gmcmotorhome.info/
Alternator Protection Cable
http://bdub.net/gmcmotorhome.info/APC.html

 

[mghamms]

Easy solution don't blue into a gfi outlet. Lots of neutral to ground connections in the GMC as they should be.
Neutral and ground are bonded in the breaker box.
--
1977 Kingsley 455 as stock as it gets except lots of Ragusa parts

 

[wrightjohn 2646]

Mike and all,

The problem is that the neutral and ground came bonded at the terminal strip at the bottom. Because that is the way it worked back in the 70’s. The neutral wires need to be separated from the grounds. You WILL have ground fault trips if left in this configuration. Your breaker box in the motorhome is consider a secondary breaker box as per NEC code they should now be modified to separate the two . Did mine and others in the summer of 2002 as we had a number of rallies at older facilities that had ground faults breaker at the pedestals and had all sorts of problems with GFI Tripping. Suggest that that you leave the grounds where they are and connect all the whites including the big white wire coming in together using a terminal strip and then use tape to insulate that connector so that it does not contact the case of the breaker box or any of the ground wires in the box. I have use one like this.

https://www.lowes.com/pd/Square-D-Load-Center-Ground-Bar-Kit/3364860

If you are not versed in electrically wiring or do not feel comfortable doing the work yourself you should seek the services of qualified electrician. Be safe not sorry!

READ THIS BELOW!

https://diy.stackexchange.com/questions/52696/why-does-a-subpanel-need-separate-ground-and-neutral

At the house I have an outside panel just below the meter that is my master panel. It allows me a manual transfer switch for my generator which isolates the overhead power from the generator and only one can be providing power and it also feed the house circuit breaker box, and the shop and barn breaker box. Both of those are now considered a secondary breaker box and the neutrals and grounds are separated.

J.R. Wright
GMC Great Laker MHC
Newsletter Editor/Publisher
GMCGL Tech Editor
GMC Eastern States Charter Member
GMCMI
78 GMC Buskirk 30’ Stretch
75 GMC Avion (Under Reconstruction)
Michigan

>
> Easy solution don't blue into a gfi outlet. Lots of neutral to ground connections in the GMC as they should be.
> Neutral and ground are bonded in the breaker box.
> --
> 1977 Kingsley 455 as stock as it gets except lots of Ragusa parts
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[Rdenney]

Check your breaker box before being too sure about that. Most RV breaker
boxes have an insulated neutral bus. And being considered a sub-panel, they
should. If the coach is grounded to neutral and you have a neutral fault in
the campground, the body can join the neutral-ground path and become
electrified.

If a GFCI outlet is tripping, there is leakage from the neutral to the
safety ground--the return current on the neutral is not matching the
supplied current on the hot.

The Onan is bonded (neutral tied to ground) because it is a primary
source--a main panel. When running on the Onan, the breaker box in the
coach is still a subpanel.

The correct solution is a transfer capability that switches neutral as well
as hot. That includes either the "manual" transfer--moving the plug from
the Onan receptacle (which carries neutral aswellashot) to the campground
receptacle--or an automatic switch that switches neutral along with hot.
The neutral inside the coach should not be grounded or tied together around
the Onan receptacle.

Rick "caution advised" Denney

> Easy solution don't blue into a gfi outlet. Lots of neutral to ground
> connections in the GMC as they should be.
> Neutral and ground are bonded in the breaker box.
> --
> 1977 Kingsley 455 as stock as it gets except lots of Ragusa parts
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com

 

[Ken H.]

Aaron,

I'm with Rick; your solution needn't be too complicated; the Coachmen
should have had separated Neutral and Ground busses.

As for the switching, I'm not sure ordinary 50A Automatic Transfer Switches
will recognize the 30A plugs you intend to use. Further, there complexity
and cost are not justified. Here's DIY version of a 30A transfer I've
used, without attention, for the past 19 years:

http://www.gmcmhphotos.com/photos/g3484-automatic-120-vac-power-source-selection.html

It's simply wired; in fact, mine's in excess space inside my replaced
circuit breaker panel (that's probably not Kosher, 'tho').

Your proposed 2nd A/C solution is certainly workable, but in the past when
working on 30A service coaches, I've just added a separate 15A CB box and
line cord for the 2nd A/C.

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, etc., etc., etc.
www.gmcwipersetc.com

> Check your breaker box before being too sure about that. Most RV breaker
> boxes have an insulated neutral bus. And being considered a sub-panel, they
> should. If the coach is grounded to neutral and you have a neutral fault in
> the campground, the body can join the neutral-ground path and become
> electrified.
> ​...
>

 

[aaron bush]

> Easy solution don't blue into a gfi outlet. Lots of neutral to ground connections in the GMC as they should be.
> Neutral and ground are bonded in the breaker box.


No! That is a potentially dangerous misconception - and one I had until recently. RV wiring is different because there is no permanent connection to
the earth (ground).

Here is one explanation.

http://beamalarm.com/Documents/120_vac_in_your_rv.html


To be clear, in my coach, the only neutral/ground connection is in the generator, which is fine when the generator is the source of AC, but it's not
okay when plugged into shore power an auto-transfer switch, or GMC's original manual system takes care of that, coachmen's did not.


--
78 Royale, rear dinette

 

[aaron bush]

I do like the set-up that GMC used, very simple and effective. But for me to implement that I either have to cut a large access hole in the side of my
coach and put a lid over it or install the generator outlet under the dinette. Coachman just put a little 2.5x2.5" access for the 30 amp shore power
cord. I don't think I could get me hand in even if I took out the little recessed cuby where the end of the shore power chord stays. the rear
"dinette" is going to be covered by a large mattress, so crawling under it every time I need to switch that plug would be an inordinate amount of
work.

So time, $$$ and effort all point me towards and automatic transfer-switch.

Aaron

> You could get rid of the transfer switch entirely??
>
> Most gmc's do not have a transfer switch, the onan wires up to a female outlet, and you either plug coach into that outlet for generator use,
>
> Or it plugs directly into shore power. Where the onan is now completly separate from coach wiring.
>
> Transfer switch could be nice, but I personally dont think it is all that nessiary.

--
78 Royale, rear dinette

 

[aaron bush]

> Aaron,
>
> I'm with Rick; your solution needn't be too complicated; the Coachmen
> should have had separated Neutral and Ground busses.

That's correct - my busses are separate at all boxes on my coach - the ground and neutral are only connected at the generator and that neutral is not
switched anywhere, nor is the ground from the generator. The comment about the neutral and ground busses being connected was not mine, and it's not
actually the problem that I have. I guess the *simplest* thing for me to do would be to put in a double pole breaker at the main generator box - but
that still leaves a convoluted set-up with more boxes, more wire, and certainly more junction boxes and wire nuts, than I actually need. Also, if I
get rid of the excess boxes and wire I will gain some usable storage space. Also doesn't resolve power for my 2nd AC on shore power. So toss that
idea.

Quote:
> As for the switching, I'm not sure ordinary 50A Automatic Transfer Switches
> will recognize the 30A plugs you intend to use. Further, there complexity
> and cost are not justified. Here's DIY version of a 30A transfer I've
> used, without attention, for the past 19 years:
>
> http://www.gmcmhphotos.com/photos/g3484-automatic-120-vac-power-source-selection.html
>
> It's simply wired; in fact, mine's in excess space inside my replaced
> circuit breaker panel (that's probably not Kosher, 'tho').

Mmmmm, this seems a bit complicated to me. It's certainly a little more than I'm easily comfortable with in terms of electrical diagrams - but it
looks like I would need two of the power relays ($50 each), two diodes(14 cents each), and two capacitors (don't know the price.) That puts me at
around before the capacitors $100, about $50 less than the switch I am looking at. Basically you built your own automatic transfer switch correct? It
might be worth $50 of my money right now to pay some one else to build it for me. I would probably enjoy doing that if I had a little more time for
it.

I'll double check on whether the PD52 transfer switch will work with 30 amps - I believe it will, but the connection instructions for that switch are
not entirely clear.

[/quote]Your proposed 2nd A/C solution is certainly workable, but in the past when
working on 30A service coaches, I've just added a separate 15A CB box and
line cord for the 2nd A/C. [/quote]

I though it would be easier to rely on the shore power breaker for the rear AC - but it's probably not as good as having my own. I might add in a
breaker there for piece of mind.

Thanks for the reply and info!

--
78 Royale, rear dinette

 

[Ken H.]

Aaron,

You overestimate the cost and complexity of a DIY auto transfer switch.
Here's a first-look relay for $18.49:
http://www.mouser.com/ProductDetail/TE-Connectivity-PB/T92S7D22-110/?qs=sGAEpiMZZMtSzCF3XBhmW6vMa%2fMpJxoP71VMV4XEUfE%3d

Only one relay is needed if you only want to transfer between shore and
generator -- just delete all the connections and components in the Inverter
section.

But if you're not comfortable with that level of electrical fabrication,
stick with the factory-built solution. But remember that with your
isolated ground system, you shouldn't need a 50A switch. I believe you'll
find that all commercial transfer switches operate just about like my
diagram, meaning that the shore power will never see the Onan's combined
Neutral and Ground connection.

HTH,

Ken H

> > Aaron,
> >
> > I'm with Rick; your solution needn't be too complicated; the Coachmen
> > should have had separated Neutral and Ground busses.
>
>
> That's correct - my busses are separate at all boxes on my coach - the
> ground and neutral are only connected at the generator and that neutral is
> not
> switched anywhere, nor is the ground from the generator. The comment about
> the neutral and ground busses being connected was not mine, and it's not
> actually the problem that I have. I guess the *simplest* thing for me to
> do would be to put in a double pole breaker at the main generator box - but
> that still leaves a convoluted set-up with more boxes, more wire, and
> certainly more junction boxes and wire nuts, than I actually need. Also, if
> I
> get rid of the excess boxes and wire I will gain some usable storage
> space. Also doesn't resolve power for my 2nd AC on shore power. So toss that
> idea.
>
>
> Quote:
> > As for the switching, I'm not sure ordinary 50A Automatic Transfer
> Switches
> > will recognize the 30A plugs you intend to use. Further, there
> complexity
> > and cost are not justified. Here's DIY version of a 30A transfer I've
> > used, without attention, for the past 19 years:
> >
> > http://www.gmcmhphotos.com/photos/g3484-automatic-120-
> vac-power-source-selection.html
> >
> > It's simply wired; in fact, mine's in excess space inside my replaced
> > circuit breaker panel (that's probably not Kosher, 'tho').
>
>
> Mmmmm, this seems a bit complicated to me. It's certainly a little more
> than I'm easily comfortable with in terms of electrical diagrams - but it
> looks like I would need two of the power relays ($50 each), two diodes(14
> cents each), and two capacitors (don't know the price.) That puts me at
> around before the capacitors $100, about $50 less than the switch I am
> looking at. Basically you built your own automatic transfer switch correct?
> It
> might be worth $50 of my money right now to pay some one else to build it
> for me. I would probably enjoy doing that if I had a little more time for
> it.
>
> I'll double check on whether the PD52 transfer switch will work with 30
> amps - I believe it will, but the connection instructions for that switch
> are
> not entirely clear.
>
> [/quote]Your proposed 2nd A/C solution is certainly workable, but in the
> past when
> working on 30A service coaches, I've just added a separate 15A CB box and
> line cord for the 2nd A/C. [/quote]
>
> I though it would be easier to rely on the shore power breaker for the
> rear AC - but it's probably not as good as having my own. I might add in a
> breaker there for piece of mind.
>
> Thanks for the reply and info!
>
>
>
>
>
>
> --
> 78 Royale, rear dinette
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[john r. lebetski]

I have a GMC upfit coach so can't go out and look at Coachmen wiring--- but from what I remember the breakers for flip/flop between shore/Onan are 2
pole each, as Coachmen uses TT-30 hookup (single hot, neutral, ground) and one pole is on the hot and one on the neutral on each breaker.
Disconnected from power and using an Ohm meter you should by concentrating on this area you should be able to find where and why the N and G are tied.
Perhaps a bad breaker in the flip/flop (easy to test) or the handy work of a PO who "fixed" it.
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[aaron bush]

Hi John,

I did all of that already, which is how I arrived at the information in my first post.

cheers,

Aaron

> I have a GMC upfit coach so can't go out and look at Coachmen wiring--- but from what I remember the breakers for flip/flop between shore/Onan
> are 2 pole each, as Coachmen uses TT-30 hookup (single hot, neutral, ground) and one pole is on the hot and one on the neutral on each breaker.
> Disconnected from power and using an Ohm meter you should by concentrating on this area you should be able to find where and why the N and G are
> tied. Perhaps a bad breaker in the flip/flop (easy to test) or the handy work of a PO who "fixed" it.

--
78 Royale, rear dinette

 

[scott nutter1]

Aaron,
We have similar models.
And mine does the same thing with the GFI plugs. It trips them.

The easiest solution for me is to not plug into a GFI plug. It has not been a inconvenience yet.
Good luck, and welcome to the forum.
Scott
--
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi.
Houston, Texas

 

[aaron bush]

Well, this is very interesting - I understand about not including the inverter. I thought I would need a 50 amp switch because the onan power would be
running through it - but you are saying that is not the case, that I only need a 30 amp switch which would be activated by my 30 AMP shore power, not
the onan? (Onan would be the default power so only the contacts would be experience more than 30 amps.)

Also, hashing this over with a friend who is more familiar with electronics than I am, then reviewing some switch terminology - I'm pretty sure I need
a DPDT relay, but the one you linked to below is DPST.

Are you thinking of a way to do this with a ST switch? Either way, if I can do it with one really, one diode and one capacitor, then I think I can
handle that.

Please realize this post makes me sound a little more electronics savy than I really am.

Aaron



> Aaron,
>
> You overestimate the cost and complexity of a DIY auto transfer switch.
> Here's a first-look relay for $18.49:
> http://www.mouser.com/ProductDetail/TE-Connectivity-PB/T92S7D22-110/?qs=sGAEpiMZZMtSzCF3XBhmW6vMa%2fMpJxoP71VMV4XEUfE%3d
>
> Only one relay is needed if you only want to transfer between shore and
> generator -- just delete all the connections and components in the Inverter
> section.
>
> But if you're not comfortable with that level of electrical fabrication,
> stick with the factory-built solution. But remember that with your
> isolated ground system, you shouldn't need a 50A switch. I believe you'll
> find that all commercial transfer switches operate just about like my
> diagram, meaning that the shore power will never see the Onan's combined
> Neutral and Ground connection.
>
> HTH,
>
> Ken H
>
>

>

> >> Aaron,
> >>
> >> I'm with Rick; your solution needn't be too complicated; the Coachmen
> >> should have had separated Neutral and Ground busses.
> >
> >
> > That's correct - my busses are separate at all boxes on my coach - the
> > ground and neutral are only connected at the generator and that neutral is
> > not
> > switched anywhere, nor is the ground from the generator. The comment about
> > the neutral and ground busses being connected was not mine, and it's not
> > actually the problem that I have. I guess the *simplest* thing for me to
> > do would be to put in a double pole breaker at the main generator box - but
> > that still leaves a convoluted set-up with more boxes, more wire, and
> > certainly more junction boxes and wire nuts, than I actually need. Also, if
> > I
> > get rid of the excess boxes and wire I will gain some usable storage
> > space. Also doesn't resolve power for my 2nd AC on shore power. So toss that
> > idea.
> >
> >
> > Quote:
> >> As for the switching, I'm not sure ordinary 50A Automatic Transfer
> > Switches
> >> will recognize the 30A plugs you intend to use. Further, there
> > complexity
> >> and cost are not justified. Here's DIY version of a 30A transfer I've
> >> used, without attention, for the past 19 years:
> >>
> >> http://www.gmcmhphotos.com/photos/g3484-automatic-120-
> > vac-power-source-selection.html
> >>
> >> It's simply wired; in fact, mine's in excess space inside my replaced
> >> circuit breaker panel (that's probably not Kosher, 'tho').
> >
> >
> > Mmmmm, this seems a bit complicated to me. It's certainly a little more
> > than I'm easily comfortable with in terms of electrical diagrams - but it
> > looks like I would need two of the power relays ($50 each), two diodes(14
> > cents each), and two capacitors (don't know the price.) That puts me at
> > around before the capacitors $100, about $50 less than the switch I am
> > looking at. Basically you built your own automatic transfer switch correct?
> > It
> > might be worth $50 of my money right now to pay some one else to build it
> > for me. I would probably enjoy doing that if I had a little more time for
> > it.
> >
> > I'll double check on whether the PD52 transfer switch will work with 30
> > amps - I believe it will, but the connection instructions for that switch
> > are
> > not entirely clear.
> >
> >
Your proposed 2nd A/C solution is certainly workable, but in the
> past when
> working on 30A service coaches, I've just added a separate 15A CB box and
> line cord for the 2nd A/C. [/quote]
>
> I though it would be easier to rely on the shore power breaker for the
> rear AC - but it's probably not as good as having my own. I might add in a
> breaker there for piece of mind.
>
> Thanks for the reply and info!
>
>
>
>
>
>
> --
> 78 Royale, rear dinette
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

[/quote]

--
78 Royale, rear dinette

 

[Ken H.]

Aaron,

If the link led to a DPST relay, I apologize for not searching more
carefully; you must use a DPDT relay, which will, indeed, be a little more
expensive. They're frequently available on eBay for pretty good prices; I
can't give you a number off-hand, but it will probably be from
Potter-Brumfield. Be sure the coil is 120 VDC NOT vac or you can't use
the capacitor to slow operation, which is definitely desirable. It would
be simple to use a lower voltage DC coil, but would complicate the circuit
by requiring a step-down transformer.

Since your house circuits are only set up for 30A load, the Onan will only
supply that current to them through the NO contacts of the relay. Whatever
method you use to supply the 2nd A/C from shore power you'll need to
utilize for the Onan also. It would, of course, be quite simple to add
another relay (requiring only 15A contacts) in parallel with the transfer
relay to handle the Onan, but it will be simpler and easier to just provide
a socket from the Onan, BEFORE the auto transfer relay, to plug the 2nd A/C
into. Another option to paralleling the primary relay would be to include
a second relay after the primary one.

Sorry if I offer too many or too complex options -- my extensive parts
inventory and 60+ years of electronics education and tinkering dominate my
thinking.

Ken H.

> Well, this is very interesting - I understand about not including the
> inverter. I thought I would need a 50 amp switch because the onan power
> would be
> running through it - but you are saying that is not the case, that I only
> need a 30 amp switch which would be activated by my 30 AMP shore power, not
> the onan? (Onan would be the default power so only the contacts would be
> experience more than 30 amps.)
>
> Also, hashing this over with a friend who is more familiar with
> electronics than I am, then reviewing some switch terminology - I'm pretty
> sure I need
> a DPDT relay, but the one you linked to below is DPST.
>
> Are you thinking of a way to do this with a ST switch? Either way, if I
> can do it with one really, one diode and one capacitor, then I think I can
> handle that.
>
> Please realize this post makes me sound a little more electronics savy
> than I really am.
>
> Aaron
>
>
>
>
>
>
>

> > Aaron,
> >
> > You overestimate the cost and complexity of a DIY auto transfer switch.
> > Here's a first-look relay for $18.49:
> > http://www.mouser.com/ProductDetail/TE-Connectivity-PB/T92S7D22-110/?qs=
> sGAEpiMZZMtSzCF3XBhmW6vMa%2fMpJxoP71VMV4XEUfE%3d
> >
> > Only one relay is needed if you only want to transfer between shore and
> > generator -- just delete all the connections and components in the
> Inverter
> > section.
> >
> > But if you're not comfortable with that level of electrical fabrication,
> > stick with the factory-built solution. But remember that with your
> > isolated ground system, you shouldn't need a 50A switch. I believe
> you'll
> > find that all commercial transfer switches operate just about like my
> > diagram, meaning that the shore power will never see the Onan's combined
> > Neutral and Ground connection.
> >
> > HTH,
> >
> > Ken H
> >
> >

> >

> > >> Aaron,
> > >>
> > >> I'm with Rick; your solution needn't be too complicated; the Coachmen
> > >> should have had separated Neutral and Ground busses.
> > >
> > >
> > > That's correct - my busses are separate at all boxes on my coach - the
> > > ground and neutral are only connected at the generator and that
> neutral is
> > > not
> > > switched anywhere, nor is the ground from the generator. The comment
> about
> > > the neutral and ground busses being connected was not mine, and it's
> not
> > > actually the problem that I have. I guess the *simplest* thing for me
> to
> > > do would be to put in a double pole breaker at the main generator box
> - but
> > > that still leaves a convoluted set-up with more boxes, more wire, and
> > > certainly more junction boxes and wire nuts, than I actually need.
> Also, if
> > > I
> > > get rid of the excess boxes and wire I will gain some usable storage
> > > space. Also doesn't resolve power for my 2nd AC on shore power. So
> toss that
> > > idea.
> > >
> > >
> > > Quote:
> > >> As for the switching, I'm not sure ordinary 50A Automatic Transfer
> > > Switches
> > >> will recognize the 30A plugs you intend to use. Further, there
> > > complexity
> > >> and cost are not justified. Here's DIY version of a 30A transfer
> I've
> > >> used, without attention, for the past 19 years:
> > >>
> > >> http://www.gmcmhphotos.com/photos/g3484-automatic-120-
> > > vac-power-source-selection.html
> > >>
> > >> It's simply wired; in fact, mine's in excess space inside my replaced
> > >> circuit breaker panel (that's probably not Kosher, 'tho').
> > >
> > >
> > > Mmmmm, this seems a bit complicated to me. It's certainly a little
> more
> > > than I'm easily comfortable with in terms of electrical diagrams -
> but it
> > > looks like I would need two of the power relays ($50 each), two
> diodes(14
> > > cents each), and two capacitors (don't know the price.) That puts me
> at
> > > around before the capacitors $100, about $50 less than the switch I am
> > > looking at. Basically you built your own automatic transfer switch
> correct?
> > > It
> > > might be worth $50 of my money right now to pay some one else to
> build it
> > > for me. I would probably enjoy doing that if I had a little more
> time for
> > > it.
> > >
> > > I'll double check on whether the PD52 transfer switch will work with
> 30
> > > amps - I believe it will, but the connection instructions for that
> switch
> > > are
> > > not entirely clear.
> > >
> > >
> Your proposed 2nd A/C solution is certainly workable, but in the
> > past when
> > working on 30A service coaches, I've just added a separate 15A CB box
> and
> > line cord for the 2nd A/C. [/quote]
> >
> > I though it would be easier to rely on the shore power breaker for the
> > rear AC - but it's probably not as good as having my own. I might add
> in a
> > breaker there for piece of mind.
> >
> > Thanks for the reply and info!
> >
> >
> >
> >
> >
> >
> > --
> > 78 Royale, rear dinette
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
> [/quote]
>
> --
> 78 Royale, rear dinette
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[hal stclair]

Ken,
The reason I use DC coils in the transfer case applications is the noise. A/C coils tend to make a lot of noise, the DC coils/relays don't.
Hal

> Aaron,
>
> If the link led to a DPST relay, I apologize for not searching more
> carefully; you must use a DPDT relay, which will, indeed, be a little more
> expensive. They're frequently available on eBay for pretty good prices; I
> can't give you a number off-hand, but it will probably be from
> Potter-Brumfield. Be sure the coil is 120 VDC NOT vac or you can't use
> the capacitor to slow operation, which is definitely desirable. It would
> be simple to use a lower voltage DC coil, but would complicate the circuit
> by requiring a step-down transformer.
>
> Since your house circuits are only set up for 30A load, the Onan will only
> supply that current to them through the NO contacts of the relay. Whatever
> method you use to supply the 2nd A/C from shore power you'll need to
> utilize for the Onan also. It would, of course, be quite simple to add
> another relay (requiring only 15A contacts) in parallel with the transfer
> relay to handle the Onan, but it will be simpler and easier to just provide
> a socket from the Onan, BEFORE the auto transfer relay, to plug the 2nd A/C
> into. Another option to paralleling the primary relay would be to include
> a second relay after the primary one.
>
> Sorry if I offer too many or too complex options -- my extensive parts
> inventory and 60+ years of electronics education and tinkering dominate my
> thinking.
>
> Ken H.
>
>

>
> > Well, this is very interesting - I understand about not including the
> > inverter. I thought I would need a 50 amp switch because the onan power
> > would be
> > running through it - but you are saying that is not the case, that I only
> > need a 30 amp switch which would be activated by my 30 AMP shore power, not
> > the onan? (Onan would be the default power so only the contacts would be
> > experience more than 30 amps.)
> >
> > Also, hashing this over with a friend who is more familiar with
> > electronics than I am, then reviewing some switch terminology - I'm pretty
> > sure I need
> > a DPDT relay, but the one you linked to below is DPST.
> >
> > Are you thinking of a way to do this with a ST switch? Either way, if I
> > can do it with one really, one diode and one capacitor, then I think I can
> > handle that.
> >
> > Please realize this post makes me sound a little more electronics savy
> > than I really am.
> >
> > Aaron
> >
> >
> >
> >
> >
> >
> >

> >> Aaron,
> >>
> >> You overestimate the cost and complexity of a DIY auto transfer switch.
> >> Here's a first-look relay for $18.49:
> >> http://www.mouser.com/ProductDetail/TE-Connectivity-PB/T92S7D22-110/?qs=
> > sGAEpiMZZMtSzCF3XBhmW6vMa%2fMpJxoP71VMV4XEUfE%3d
> >>
> >> Only one relay is needed if you only want to transfer between shore and
> >> generator -- just delete all the connections and components in the
> > Inverter
> >> section.
> >>
> >> But if you're not comfortable with that level of electrical fabrication,
> >> stick with the factory-built solution. But remember that with your
> >> isolated ground system, you shouldn't need a 50A switch. I believe
> > you'll
> >> find that all commercial transfer switches operate just about like my
> >> diagram, meaning that the shore power will never see the Onan's combined
> >> Neutral and Ground connection.
> >>
> >> HTH,
> >>
> >> Ken H
> >>
> >>

> >>

> >>>> Aaron,
> >>>>
> >>>> I'm with Rick; your solution needn't be too complicated; the Coachmen
> >>>> should have had separated Neutral and Ground busses.
> >>>
> >>>
> >>> That's correct - my busses are separate at all boxes on my coach - the
> >>> ground and neutral are only connected at the generator and that
> > neutral is
> >>> not
> >>> switched anywhere, nor is the ground from the generator. The comment
> > about
> >>> the neutral and ground busses being connected was not mine, and it's
> > not
> >>> actually the problem that I have. I guess the *simplest* thing for me
> > to
> >>> do would be to put in a double pole breaker at the main generator box
> > - but
> >>> that still leaves a convoluted set-up with more boxes, more wire, and
> >>> certainly more junction boxes and wire nuts, than I actually need.
> > Also, if
> >>> I
> >>> get rid of the excess boxes and wire I will gain some usable storage
> >>> space. Also doesn't resolve power for my 2nd AC on shore power. So
> > toss that
> >>> idea.
> >>>
> >>>
> >>> Quote:
> >>>> As for the switching, I'm not sure ordinary 50A Automatic Transfer
> >>> Switches
> >>>> will recognize the 30A plugs you intend to use. Further, there
> >>> complexity
> >>>> and cost are not justified. Here's DIY version of a 30A transfer
> > I've
> >>>> used, without attention, for the past 19 years:
> >>>>
> >>>> http://www.gmcmhphotos.com/photos/g3484-automatic-120-
> >>> vac-power-source-selection.html
> >>>>
> >>>> It's simply wired; in fact, mine's in excess space inside my replaced
> >>>> circuit breaker panel (that's probably not Kosher, 'tho').
> >>>
> >>>
> >>> Mmmmm, this seems a bit complicated to me. It's certainly a little
> > more
> >>> than I'm easily comfortable with in terms of electrical diagrams -
> > but it
> >>> looks like I would need two of the power relays ($50 each), two
> > diodes(14
> >>> cents each), and two capacitors (don't know the price.) That puts me
> > at
> >>> around before the capacitors $100, about $50 less than the switch I am
> >>> looking at. Basically you built your own automatic transfer switch
> > correct?
> >>> It
> >>> might be worth $50 of my money right now to pay some one else to
> > build it
> >>> for me. I would probably enjoy doing that if I had a little more
> > time for
> >>> it.
> >>>
> >>> I'll double check on whether the PD52 transfer switch will work with
> > 30
> >>> amps - I believe it will, but the connection instructions for that
> > switch
> >>> are
> >>> not entirely clear.
> >>>
> >>>
> > Your proposed 2nd A/C solution is certainly workable, but in the
> >> past when
> >> working on 30A service coaches, I've just added a separate 15A CB box
> > and
> >> line cord for the 2nd A/C.

>>
>> I though it would be easier to rely on the shore power breaker for the
>> rear AC - but it's probably not as good as having my own. I might add
> in a
>> breaker there for piece of mind.
>>
>> Thanks for the reply and info!
>>
>>
>>
>>
>>
>>
>> --
>> 78 Royale, rear dinette
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
> [/quote]
>
> --
> 78 Royale, rear dinette
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

[/quote]

--
1977 Royale 101348,

1977 Royale 101586, Diesel powered,

1975 Eleganza II, 101230

1974 Eagle Bus 45',w/slideout

 

[JShot]

AAron,
I hate sticking my 2 cents in where I might not know what I'm talking about, but here goes...

On our 78 Royal (Coachmen) center kitchen, I discovered a transfer switch mounted on the rear side of the plywood box that surrounds the Onan. This is
inside the coach. I didn't know it was there for four years.

We were at a campground, and had lost all power to the coach. Finally traced the power from the pedestal to the coach and found the T switch, and the
loose wires inside it. It was a pain to fix as we had to use a mirror to see in the T switch box because it's so close the the rear of the coach.

Obviously I don't know if you have looked there. I do know that Coachmen put the switches in a lot of their units.

On ours, the switch was/is wired with shore power being the primary source, and the Onan being secondary.

John
--
John Shotwell
Ridgeville Corners, OH
78 Royale Center Kitchen
Web Site: GMCmhRegistry.com
Email: john at gmcmhregistry dot com

 

[aaron bush]

lol. Well, now I understand why you keep saying "it's simple!" I really appreciate the info. At the very least you've let me know that building my own
automatic transfer switch is a possibility. I'll think about it a bit more before I make a decision.

One question that might be of interest to others though - what kind of delay time do you get with the capacitor? And does the diode in the capacitor
circuit cure the AC hum? or is it there for another reason?

> Aaron,
>
> If the link led to a DPST relay, I apologize for not searching more
> carefully; you must use a DPDT relay, which will, indeed, be a little more
> expensive. They're frequently available on eBay for pretty good prices; I
> can't give you a number off-hand, but it will probably be from
> Potter-Brumfield. Be sure the coil is 120 VDC NOT vac or you can't use
> the capacitor to slow operation, which is definitely desirable. It would
> be simple to use a lower voltage DC coil, but would complicate the circuit
> by requiring a step-down transformer.
>
> Since your house circuits are only set up for 30A load, the Onan will only
> supply that current to them through the NO contacts of the relay. Whatever
> method you use to supply the 2nd A/C from shore power you'll need to
> utilize for the Onan also. It would, of course, be quite simple to add
> another relay (requiring only 15A contacts) in parallel with the transfer
> relay to handle the Onan, but it will be simpler and easier to just provide
> a socket from the Onan, BEFORE the auto transfer relay, to plug the 2nd A/C
> into. Another option to paralleling the primary relay would be to include
> a second relay after the primary one.
>
> Sorry if I offer too many or too complex options -- my extensive parts
> inventory and 60+ years of electronics education and tinkering dominate my
> thinking.
>
> Ken H.
>
>

>
> > Well, this is very interesting - I understand about not including the
> > inverter. I thought I would need a 50 amp switch because the onan power
> > would be
> > running through it - but you are saying that is not the case, that I only
> > need a 30 amp switch which would be activated by my 30 AMP shore power, not
> > the onan? (Onan would be the default power so only the contacts would be
> > experience more than 30 amps.)
> >
> > Also, hashing this over with a friend who is more familiar with
> > electronics than I am, then reviewing some switch terminology - I'm pretty
> > sure I need
> > a DPDT relay, but the one you linked to below is DPST.
> >
> > Are you thinking of a way to do this with a ST switch? Either way, if I
> > can do it with one really, one diode and one capacitor, then I think I can
> > handle that.
> >
> > Please realize this post makes me sound a little more electronics savy
> > than I really am.
> >
> > Aaron
> >
> >
> >
> >
> >
> >
> >

> >> Aaron,
> >>
> >> You overestimate the cost and complexity of a DIY auto transfer switch.
> >> Here's a first-look relay for $18.49:
> >> http://www.mouser.com/ProductDetail/TE-Connectivity-PB/T92S7D22-110/?qs=
> > sGAEpiMZZMtSzCF3XBhmW6vMa%2fMpJxoP71VMV4XEUfE%3d
> >>
> >> Only one relay is needed if you only want to transfer between shore and
> >> generator -- just delete all the connections and components in the
> > Inverter
> >> section.
> >>
> >> But if you're not comfortable with that level of electrical fabrication,
> >> stick with the factory-built solution. But remember that with your
> >> isolated ground system, you shouldn't need a 50A switch. I believe
> > you'll
> >> find that all commercial transfer switches operate just about like my
> >> diagram, meaning that the shore power will never see the Onan's combined
> >> Neutral and Ground connection.
> >>
> >> HTH,
> >>
> >> Ken H
> >>
> >>

> >>

> >>>> Aaron,
> >>>>
> >>>> I'm with Rick; your solution needn't be too complicated; the Coachmen
> >>>> should have had separated Neutral and Ground busses.
> >>>
> >>>
> >>> That's correct - my busses are separate at all boxes on my coach - the
> >>> ground and neutral are only connected at the generator and that
> > neutral is
> >>> not
> >>> switched anywhere, nor is the ground from the generator. The comment
> > about
> >>> the neutral and ground busses being connected was not mine, and it's
> > not
> >>> actually the problem that I have. I guess the *simplest* thing for me
> > to
> >>> do would be to put in a double pole breaker at the main generator box
> > - but
> >>> that still leaves a convoluted set-up with more boxes, more wire, and
> >>> certainly more junction boxes and wire nuts, than I actually need.
> > Also, if
> >>> I
> >>> get rid of the excess boxes and wire I will gain some usable storage
> >>> space. Also doesn't resolve power for my 2nd AC on shore power. So
> > toss that
> >>> idea.
> >>>
> >>>
> >>> Quote:
> >>>> As for the switching, I'm not sure ordinary 50A Automatic Transfer
> >>> Switches
> >>>> will recognize the 30A plugs you intend to use. Further, there
> >>> complexity
> >>>> and cost are not justified. Here's DIY version of a 30A transfer
> > I've
> >>>> used, without attention, for the past 19 years:
> >>>>
> >>>> http://www.gmcmhphotos.com/photos/g3484-automatic-120-
> >>> vac-power-source-selection.html
> >>>>
> >>>> It's simply wired; in fact, mine's in excess space inside my replaced
> >>>> circuit breaker panel (that's probably not Kosher, 'tho').
> >>>
> >>>
> >>> Mmmmm, this seems a bit complicated to me. It's certainly a little
> > more
> >>> than I'm easily comfortable with in terms of electrical diagrams -
> > but it
> >>> looks like I would need two of the power relays ($50 each), two
> > diodes(14
> >>> cents each), and two capacitors (don't know the price.) That puts me
> > at
> >>> around before the capacitors $100, about $50 less than the switch I am
> >>> looking at. Basically you built your own automatic transfer switch
> > correct?
> >>> It
> >>> might be worth $50 of my money right now to pay some one else to
> > build it
> >>> for me. I would probably enjoy doing that if I had a little more
> > time for
> >>> it.
> >>>
> >>> I'll double check on whether the PD52 transfer switch will work with
> > 30
> >>> amps - I believe it will, but the connection instructions for that
> > switch
> >>> are
> >>> not entirely clear.
> >>>
> >>>
> > Your proposed 2nd A/C solution is certainly workable, but in the
> >> past when
> >> working on 30A service coaches, I've just added a separate 15A CB box
> > and
> >> line cord for the 2nd A/C.

>>
>> I though it would be easier to rely on the shore power breaker for the
>> rear AC - but it's probably not as good as having my own. I might add
> in a
>> breaker there for piece of mind.
>>
>> Thanks for the reply and info!
>>
>>
>>
>>
>>
>>
>> --
>> 78 Royale, rear dinette
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
> [/quote]
>
> --
> 78 Royale, rear dinette
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

[/quote]

--
78 Royale, rear dinette

 

[john r. lebetski]

I love the Coachmen interiors, but sure am glad I have a GMC upfit coach with 14-50 setup. If I owned a Coachmen I would probably convert to 14-50
and be done with it saving weight and space and complexity as a bonus. Keep us posted.
--
John Lebetski
Woodstock, IL
77 Eleganza II