Bus Conversions dot Com Bulletin Board
December 20, 2014, 04:25:22 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
News: If you had an Online Subscription: The dog will not eat it.
   Home   Help Forum Rules Search Calendar Login Register BCM Home Page Contact BCM  
Pages: 1 2 [All]   Go Down
  Print  
Author Topic: 50A shore cable a/c question  (Read 2557 times)
white-eagle
Hero Member
*****
Offline Offline

Posts: 1184





Ignore
« on: August 01, 2007, 07:47:07 AM »

we just noticed last nite that neither roof a/c unit worked at home when they did just work on the way home with the generator.  i checked all the breakers etc., then fired up the genset and they worked fine.
we have a 30A plug at the house.  i run the bus 50A cable into a 50/30 adapter cable, then plug that into the 30A 25' extension to get to the house plug.  i knew the week before, i had the 50A extension cable plugged into all this the week before and it worked, so i replugged everything as before, and it all worked and the a/c came on. 
so the question is:  why did the a/c work with the bus cable plugged into the 50a extension, then adaptor, then 30A extension, but not when the 50a extension removed?
Logged

Tom
1991 Eagle 15 and proud of it.
8V92T, 740, Fulltime working on the road.

Fran was called to a higher duty 12/16/13. I lost my life navigator.
Dreamscape
Guest

« Reply #1 on: August 01, 2007, 07:52:02 AM »

I had a similar problem yesterday. I installed a new 50 amp cable to the bus panel, bought a 30 to 50 dogbone, plugged it into a 30 to 15 cord. Nothing worked even when I had 120v to the breaker. I tore apart the 30 amp receptacle and found the neutral wire was attached to the ground. After installing the wires into the proper place, all worked great.
Don't know if this helps or not.

Happy Trails,

Paul

Dreamscape
Logged
edroelle
Sr. Member
****
Offline Offline

Posts: 351


1998 Royale Prevost




Ignore
« Reply #2 on: August 01, 2007, 07:59:26 AM »

Tom,
If you have an automatic relay between generator and shore, it may be sticking.  If you don't have an automatic (and I hate to suggest this), did you remember to manually make the switch?

I have had relays stick, and, I have done some real dumb things.

Ed Roelle
Flint, MI
Logged
white-eagle
Hero Member
*****
Offline Offline

Posts: 1184





Ignore
« Reply #3 on: August 01, 2007, 08:18:53 AM »

thanks for the possible answers, but let me explain further.
we don't have an auto transfer.  We never plug the shore power in, then use the genset.  the genset would power the shore line.  We have a short shore line that has a round 4 prong plug that goes into the bus with the standard 50 amp male on the other end.  Jack Conrad hooked it up for me when the original transfer switch failed before i bought the bus.
all i did to correct the a/c problem was to add the 50a 25' extension cord between my 15ft 50a bus cord and the dogbone. 

somewhere, i was thinking that a leg wasn't connected to anything solid with the dogbone, but is connected with the 50a extension??
Logged

Tom
1991 Eagle 15 and proud of it.
8V92T, 740, Fulltime working on the road.

Fran was called to a higher duty 12/16/13. I lost my life navigator.
Dreamscape
Guest

« Reply #4 on: August 01, 2007, 08:29:33 AM »

Do a continuity test on all blades of each piece. Something is not hooked up right. Are the plugs molded or take apart?

Paul
Logged
Buffalo SpaceShip
Hero Member
*****
Offline Offline

Posts: 591





Ignore
« Reply #5 on: August 01, 2007, 09:50:15 AM »

Do a continuity test on all blades of each piece. Something is not hooked up right. Are the plugs molded or take apart?

Paul

Agreed. All the dogbone does is tie the two hot legs of 50a together for 30a. Neutral and Ground should remain isolated on all cordsets (to be within code). Remove all power and continuity test everything. Check for neutral ground bonds while you are at it (should bond at the genset, at the inverter, and at "the pole" only... anything else is dangerous).

I'm assuming that there's not 220v items on your coach.

HTH,
Brian B.
« Last Edit: August 01, 2007, 12:15:32 PM by Buffalo SpaceShip » Logged

Brian Brown
4108-216 w/ V730
Longmont, CO
Stan
Hero Member
*****
Offline Offline

Posts: 973




Ignore
« Reply #6 on: August 01, 2007, 12:09:57 PM »

manasst: If I understand this correctly, this is what you have:

Doesn't work: Shore Cord - dogbone - 30 amp cable - 120 volt 30 amp receptacle

Works OK: Same shore cord - 50 amp cable - same dogbone - same receptacle

I would say you have an open in the 30 amp cable.
Logged
Sean
Geek.
Hero Member
*****
Offline Offline

Posts: 2553


'85 Neoplan Spaceliner "Odyssey"


WWW

Ignore
« Reply #7 on: August 01, 2007, 02:22:25 PM »

I can think of only one way this exact set of symptoms could occur, which leads me to ask the following questions:

(1) Is the 50a<->30a adapter a store-bought item with molded ends, or "home built"?

(2) Does your bus make use of both incoming legs of the 50-amp cord (12,000 watts) or does it only use one leg (6,000 watts)?

On a separate note, if your setup is such that running the generator will back-feed the shore cord, you have some serious issues that need to be addressed.  Setting aside, for a moment, the code violations and potential for killing someone upstream of your coach should the generator start while the shore cord is connected, the fact that there is likely a permanent ground-to-neutral bond in the generator means that you will have a double-bonding issue when on shore power, thus returning about half off your shore current through the ground -- another potentially lethal situation.  Also, it likely doesn't do the windings any good to have them connected to an external source of power, and I think you'll find the genny head is heating up while you are on shore power.  FWIW.

Let me know the answer to the two questions, and I think I can tell you where the problem lies.

-Sean
http://OurOdyssey.BlogSpot.com
Logged

Full-timing in a 1985 Neoplan Spaceliner since 2004.
Our blog: http://OurOdyssey.BlogSpot.com
white-eagle
Hero Member
*****
Offline Offline

Posts: 1184





Ignore
« Reply #8 on: August 01, 2007, 05:05:17 PM »

first:  stan, the 30 amp extension stays in the loop.  the only change was adding the 50a extension.  with the 50a, a/c works.  without the 50a extension, no a/c.  same  shore cord, same dog bone, same 30a extension, same shore plug at the garage.  bus shore ->50a > dogbone> 30a>house 30a plug = A/C.

2nd. Sean, i believe there originally was an auto switch on the bus.  when i bought the bus, no shore power at all since switch didn't work.  Jack Conrad fixed it by taking out the switch and putting in just a plug for shore power which needs to be unplugged when the genset is on or else you have a set of hot leads at the shore end of the cable.  i never power the genset when i'm plugged into anything, nor do i leave the cable out, always rolled up and put away.

i'm not exactly the electrical expert as you can tell.  i suspect the dogbone (purchased with molded ends) is not putting any kind of juice on one leg so the a/c circuit doesn't power up.  all other circuits including hot water do seem to work.

obviously, i cannot run the hot water, and both a/c units when i'm plugged into 30 amp without blowing the breaker in the house.
i have not run any continuity tests yet on any connections.  Do i unplug the power before i run the continuity tests?
just joking, i'm not an expert, but i'm not that ignorant either.
thanks for the pointers on what to check.  i will post results.
Logged

Tom
1991 Eagle 15 and proud of it.
8V92T, 740, Fulltime working on the road.

Fran was called to a higher duty 12/16/13. I lost my life navigator.
Buffalo SpaceShip
Hero Member
*****
Offline Offline

Posts: 591





Ignore
« Reply #9 on: August 01, 2007, 05:26:41 PM »

...and putting in just a plug for shore power which needs to be unplugged when the genset is on or else you have a set of hot leads at the shore end of the cable.  i never power the genset when i'm plugged into anything, nor do i leave the cable out, always rolled up and put away.

You should fix this immediately. The hot prongs on a male plug are destined to short out something (or someone!). The age-old "manual transfer-switch" still works: put a receptacle on your genset output. Then, you either plug your shore cord into it or the shore receptacle. No hot leads, no back-feeding, no hot windings... no tragedies.

HTH,
Brian B.
Logged

Brian Brown
4108-216 w/ V730
Longmont, CO
Sean
Geek.
Hero Member
*****
Offline Offline

Posts: 2553


'85 Neoplan Spaceliner "Odyssey"


WWW

Ignore
« Reply #10 on: August 01, 2007, 05:49:14 PM »

OK, take your voltmeter and check the voltage on your dogbone -- you should read ~117 volts between each of the outer two slots and the center slot.  You may need to wiggle the test leads a bit.

If you read voltage on both sides, then my guess is that your dogbone is simply worn out.  By chance, the blade on the 50A extension makes good contact in the worn slot on the dogbone, but the blade on the shore cord does not (possibly one is bent slightly differently than the other).

If you read voltage on only one side of the dogbone, then the dogbone has an "open" internally, and your 50A extension is swapping the hots between plug and receptacle (not really kosher, but not unheard of either).

In either case, the cure will be to replace the dogbone.

Once you get this fixed, though, you will definitely need to attend to the other issue -- it's an accident waiting to happen.

-Sean
http://OurOdyssey.BlogSpot.com
Logged

Full-timing in a 1985 Neoplan Spaceliner since 2004.
Our blog: http://OurOdyssey.BlogSpot.com
JackConrad
Orange Blossom Special II
Global Moderator
Hero Member
*****
Offline Offline

Posts: 4447


73' MC-8 8V71/HT740 Southwest Florida


WWW
« Reply #11 on: August 01, 2007, 06:35:34 PM »

Tom,
    It has been a while, but I think I repaced your bad transfer switch with a new one.  I think each of your ACs is on a separate leg of the 50 amp cord.  Jack
« Last Edit: August 01, 2007, 06:38:49 PM by JackConrad » Logged

Growing Older Is Mandatory, Growing Up Is Optional
Arcadia, Florida, When we are home
http://s682.photobucket.com/albums/vv186/OBS-JC/
white-eagle
Hero Member
*****
Offline Offline

Posts: 1184





Ignore
« Reply #12 on: August 02, 2007, 02:04:17 AM »

no transfer switch or at least not any automatic one.  Jack, see the note i sent you. 

i remember trying to get hold of the auto txfr switch company listed on the old broken one and they were out of business, so i kept the shore connection the way it was.   the air conditioner breakers are on opposite sides in the "fuse" box, 100amp breaker main.  is that what you meant about separate legs?

i also found out the other day when i called powertech for a manual that my genset is a 12kw, not the 10kw marked on the outside cover, so maybe that's why 100amp main breaker?

i'll check more on the volts and stuff later today per some of the previous tips.  and do some more checking on just what the electrical boxes in genset compartment actually do.

Sorry for not explaining well, but there was no manual or documentation with this bus.  Mr. Schofield said he never intended to sell, and he knew where everything was.  i've been trying to document (and learn)as needed when i'm correcting or fixing or enhancing.  and moma said "if it ain't broke, don't fix it". 
Logged

Tom
1991 Eagle 15 and proud of it.
8V92T, 740, Fulltime working on the road.

Fran was called to a higher duty 12/16/13. I lost my life navigator.
JackConrad
Orange Blossom Special II
Global Moderator
Hero Member
*****
Offline Offline

Posts: 4447


73' MC-8 8V71/HT740 Southwest Florida


WWW
« Reply #13 on: August 02, 2007, 05:33:24 AM »

Tom,
   I got your message.  My memory just isn't what it used to be.  I remember we tried to get it going as quickly as possible so you could get on the road.  Go to Ebay and search for 50 Amp transfer switch.  I found one similar to the one we removed from your bus. I think I paid around $50-$75.  Jack
Logged

Growing Older Is Mandatory, Growing Up Is Optional
Arcadia, Florida, When we are home
http://s682.photobucket.com/albums/vv186/OBS-JC/
white-eagle
Hero Member
*****
Offline Offline

Posts: 1184





Ignore
« Reply #14 on: August 02, 2007, 08:03:15 PM »

ok, did some measuring and now i'm more confused.  on the 30a shore female plug at the house, 123v between the primary and ground, primary and neutral, 0v on neutral and ground.  the female end of the 30a extension shows exactly the same.  the female 50A end of the 30/50 dogbone shows 123v on the left primary between it and ground, or it and neutral.  the right primary shows 119-129v between it and ground, or it and neutral.  there is no voltage between neutral and ground.  the bus end shore plug is a round L1430c lockable.  it shows the same as the dogbone whether i connect it to the dogbone directly or insert the 50a extension cable.  but the A/C only works when the 50A extension cord is in use.

i don't see any difference to justify the a/c issue?  they seem to read like i think they should?? Huh

one good thing is i took pictures of the power relays where the genset and shore lines connect to bus breaker box, opened up the breaker box and took pics, and found the 12v connections (not labeled).  None of it is documented, but at least i don't have to keep opening the boxes to verify what i saw. i also know that the washer/dryer is on the same breaker as the bedroom, and that i have a magnetek converter/charger that may have a recall due to fire hazard. Sad
Logged

Tom
1991 Eagle 15 and proud of it.
8V92T, 740, Fulltime working on the road.

Fran was called to a higher duty 12/16/13. I lost my life navigator.
Buffalo SpaceShip
Hero Member
*****
Offline Offline

Posts: 591





Ignore
« Reply #15 on: August 02, 2007, 11:21:15 PM »

Well, a L1430c is a 30A connector. How is the 50a dogbone or extension feeding this plug? You likely have some reverse-polarity going on at the L1430c that the 50a extension rectifies. If you go to your panel, each A/C is on a different leg. On the A/C that doesn't work w/o the extension, measure the voltage from hot to neutral and ground with each condition (with and without 50a extension). You'll likely find that voltage is zero from hot to neutral w/o the extension... and/or you'll find voltage across neutral and ground which points back to the mis-wired L1430c plug.

Considering the wiring of your coach, you likely don't have a separate grounding bus bar on your panel, which should trip the breaker when current travels through the ground wire. These are the bonding issues I spoke about previously.

And yes, something is broke.  Wink Time to fix it! Grin

Brian B.
Logged

Brian Brown
4108-216 w/ V730
Longmont, CO
Sean
Geek.
Hero Member
*****
Offline Offline

Posts: 2553


'85 Neoplan Spaceliner "Odyssey"


WWW

Ignore
« Reply #16 on: August 02, 2007, 11:37:17 PM »

Tom,

You are not the only one getting more confused by the minute....

You've written several times that you have a 50-amp shore cord, and a 50-amp extension cord.  But now you are telling us that the 50-amp cord connects to your bus with an L14-30, which is a termination that is only rated for 30 amps.  Between that and the generator-shore parallel connection with no switching, I have to say that your entire electrical system is suspect, and I don't think we can make any assumptions at all about it without a good, thorough inspection.

Probably not what you want to hear, but I would start by addressing some of these major deficiencies, and trying to diagram out just exactly what you have.  With things as mis-wired as they are, there is no telling what sort of results you will get from any shore connection arrangement at all.

Right off the bat, I would (1) remove the shore and generator parallel connection, either by installing a transfer switch (manual or automatic), or by installing a 50-amp receptacle on the generator and using the shore cord itself to make the switch and (2) replace the L14-30 with a proper 50-amp connector.  Then I would meter out all your cords and adapters to make certain they are properly wired.  Once that's done, you will have a good starting point to diagnose the A/C problem.

All that said, I am sticking with my theory that the shore cord is not making good contact with the dogbone, but the extension cord makes good contact at both ends.  Your meter may show good voltage, but that is at a no-load state -- adding a load can cause significant voltage drop over a marginal connection, enough so that the A/C will not start.  (Running through the under-sized connector is not helping this situation any.)

-Sean
http://OurOdyssey.BlogSpot.com
Logged

Full-timing in a 1985 Neoplan Spaceliner since 2004.
Our blog: http://OurOdyssey.BlogSpot.com
gumpy
Some Assembly Required
Hero Member
*****
Offline Offline

Posts: 3353


Slightly modified 1982 MC9


WWW

Ignore
« Reply #17 on: August 03, 2007, 08:07:15 AM »

I'm with Sean on this one.  I think it's a matter of not getting a good connection between the dogbone and the shore cord.

I'd really like to see some photos of all the ends of the cords. Especially the 50 amp extension cord. What are you using for a female end on that one, since I've not been able to find a replacement plug for that one yet.

As indicated by Brian, the dogbone crosses the incoming 30 amp hot to the two 50 amp conductors in the output, so both hots in your 50 amp (30 amp??) extension and shore cords should be hot, regardless whether the extension is in or not. It's possible  you have two wiring issues, one in the shore cord, and one in the extension, which are canceling each other out. That's a scary thought, because it could mean a neutral or safety ground is miswired in the shore cord, and the extension was wired to make the shore cord work.

craig
Logged

Craig Shepard
Located in Minnesquito

http://bus.gumpydog.com - "Some Assembly Required"
white-eagle
Hero Member
*****
Offline Offline

Posts: 1184





Ignore
« Reply #18 on: August 03, 2007, 08:18:35 PM »

Craig, Sean, Brian and Jack, etc. 

the 50a extension is a std molded end at each end.  so is the dogbone.  CampWorld specials.  the 30 or 50 amp cable with the l1430 to the bus male receptacle is homemade and has the 4 prong standard 50a connector.  since i drove over and squashed it, then replaced the shore end, i guess that cable end is suspect.  the 30A extension is also a homemade that i think i replaced ends on. and finally, i'm the one that put a 30A breaker in the garage and the receptacle outside for the bus.
i'm trying to figure out hubble or marinco receptacle and female cable end.  i've been looking at 50a, 120/250v ends.  geesh, are they expensive.  at an electrical supply house, a stove receptacle in the bus and the 4 prong male for the cable would only be $35, but i suppose a male on each end of the cable violates all sorts of safety rules and NEC., so i didn't buy it but i sure don't understand the extra $150 for the "correct" ones from campworld or west marine.
as i said b4, this is and has been a learning experience.  We will get this fixed soon even though it's sort of working.  i do understand accidents waiting to happen and i don't want to be one.  any comments as to best brand for transfer switch.  a couple generac 100a on ebay for around $300, with a panel that i don't think i need.
Logged

Tom
1991 Eagle 15 and proud of it.
8V92T, 740, Fulltime working on the road.

Fran was called to a higher duty 12/16/13. I lost my life navigator.
Pages: 1 2 [All]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.18 | SMF © 2013, Simple Machines Valid XHTML 1.0! Valid CSS!