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Author Topic: Shore Power connection for my S&S in all this heat  (Read 3098 times)
Gary LaBombard
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« on: August 08, 2006, 02:37:58 AM »

I am passing a few moments before going to hospital for a minor (Old Age Connection) and have been at a local campground that is (Army Corps of Engineers sponsored).  We have been camping there and will be going back today after hospital visit.  The temperatures have been ungodly hot as nearly everywhere. 

We have been using our one roof top air conditoner on the 1988 Tioga, Arrow S&S all day and night to stay comfortable with grandkids etc.  Well, They have the shore power boxes connected so there is a (3 prong 30 amp. connection and next to it a 4 prong 50 amp connection).  My connection of coarse should be the 30 amp 3 prong that I normally use.  Welll, between 1pm & 5pm my circut breaker on my power converter for the Air Conditioner only circut keeps cutting off and needing resetting to continue cooling.  (The converter in my S&S Air Conditioner only circut breaker is a "20 amp" circut breaker).  I am not sure of the age of my roof top, I suspect it is the original from birth of S&S.  It throttles on and off to a different speed or sound every few moments but I am told this is normal and can't put it in the correct words to explain to you high tech air conditiioner busnuts.  It stil cools very good when there is no interuption of power at high speed & max cooling available setting.

Next to me on both sides is two very brand new high end rigs, 42 footers, 3-4 roof airs each and all pumping all day long I believe by the outside sound.  Positive they are using 50 amp service by the size of the entrance cords for sure. 

What my question is as dumb as it may sound, I need to get versed on the (30amp / 50amp) connectons when I get to that point on my Eagle conversion also.  But, I had such bad luck with power input from the 30 amp. connection I was using I did not know if I used one of those cords that converts 50 amp service into a 30 amp at the control box that I would get a better power supply??  I am not sure if the 30 amp is really only about 25 amps and the 50 amp is only two legs with 25 amps each side when used??  Please no long explanations at this time, I can consume only so much here lately with other problems I have been having.  I know this sounds nuts to some especially those versed in correct power connections but I have seen this discussed so many times and when I read some of the answers to them I say, WHAT??? 

I have not tried this out yet, I am going back to campsite later today, but curious if I would get a better power supply from 50 amp reduced through power adapter cord down to 30 amp for my use.  I believe with this intense heat and everyone pulling with full power on their airs that the camp site power supply's drop down to a dangerous (Brown out level) and thank god for the circut breakers doing their job.   Oh, one more thought, does the amount of protection from a circut breaker ever break down from being reset so many times, or in other words should I consider replacing my circut breaker also.  Who know how often this has happened to the previous owner, (They all lie) when you BUY!!  I know, another stupid question but is it so stupid to us that admit their lack of knowledge in this area?? 

I will check for reply's hopefully before we go back to camp today. 
Thanks ahead of time.

Gary
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Gary
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« Reply #1 on: August 08, 2006, 04:26:44 AM »

Gary,

Short answer;

Check with a VOM what the actual voltage is at the plug.

As voltage drops, amp use increases and may explain your breaker tripping.

Also older A/C's compressors and fan motor will be drawing more power.

Anyway, good luck on everything,

Cliff
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« Reply #2 on: August 08, 2006, 05:35:09 AM »

In normal wiring:
3 prong plug:
ground
neutral
hot


4 prong plug:
ground
neutral
hot
hot


The voltage between legs (prongs)
ground to neutral = 0
ground to hot = 115v (nominal)
neutral to hot = 115v (nominal)
hot to hot = 230v (nominal) - 4 prong


If the campground voltage is dropping too low, your A/C unit will pull more amps to get the power it needs (power = volts X amps) & trip your inside breaker.

It won't matter if you are plugged into 30A or 50A.

Some of the newer A/C's tolerate low voltage better than the older units.

Let me know when you're back in town.

Good Luck!
kyle4501


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« Reply #3 on: August 08, 2006, 05:38:34 AM »

Another short answer:

Yes, breakers do wear out and trip at lower levels.

Len
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« Reply #4 on: August 08, 2006, 07:38:05 AM »

If you have thermal circut breakers, in the heat with the extra load an A/C naturally takes as the heat rises, and the extra heat on the breaker maybe causing the tripping.  I found that this is the case with my bus when running down the road with all three A/C's running.  Since my breakers are enclosed in a cabinet, they get hot and trip.  I installed a small computer fan to politely push some air through and it took care of that.  Suggest you aim a fan at the circut breaker to keep the heat down.
On 50 amp plug, the round prong is the ground, the middle blade is the neutral, with the right and left blade being leg one and two.  Since leg one and two are off phase by 180 degrees (as designed on a generator), each leg when connected to the neutral will read 120v.  When you check the two legs together they will read 240v.  So in actuality, you have two separate 50 amp services coming into the bus for a total of 100 amps.  I have my bus wired for straight 50 amp only which means I only use one leg of the 50 amp plug.  While this hasn't been a problem since I can run two A/C's plus other items on it, some all electric coaches need the full 100 amp split service.  What I like is that I don't have to be constantly figuring out what to use and what not to use to keep the balance between the two legs relatively equal.  This isn't too much a concern when on the power pole, but can be an issue when using the generator, since it could create an imbalance on the generator and heat up one leg but not the other.  Hope this helps, Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #5 on: August 08, 2006, 08:40:19 AM »

Gary, the dogbone adapter to go from 50A to 30A would be a safety violation if you don't have a main 30A breaker for your rig (S&S's don't always have these). In that situation, the shore cord could pull more juice than the conductors inside it are allowed. If you DO have a main breaker, the dogbone will make no difference on the power supplied to your rig.

Even if you do have a main breaker, something is up if you're blowing a circuit when no one else nearby is tripping theirs. I'd take apart the breaker box (with the cord unplugged, of course!) and look for corrosion on the wires for the A/C breaker, its neutral and ground. And do the same on your shore cord connection at the panel. Check wire sizes in there while you're at it. Could also be a faulty breaker, as suggested.

I've run TWO DuoTherm 13.5k's successfully off of a 30A shore cord, when their compressors never started at the same time. Eventually, at least on paper, it should have tripped the main, but ran this way for a few days.

Check your park voltage with a VOM. I really suspect it's somthing in your rig, either the breaker, the wires, the A/C... or all of the above.

Good luck and please post back your findings.
Brian

p.s. the 50A plug will supply TWO legs at 120v/50A for a total of 12,000w. You can get 240v between the hots, but some rigs don't need devices wired for 240v.  Your 30A connection only supplies ONE 30A leg @ 120v= 3,600w. Now you can see why a 50A connection is so much more useful for a BIG coach... over THREE times the juice.
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Gary LaBombard
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« Reply #6 on: August 08, 2006, 09:42:27 AM »

Thanks everyone for the advice up to the point when I left to go back to camp ground.  I am taking a VOM with me to measure power drop when air comes on or changes speed or what ever it does constantly when on.  I do suspect like cliff & Kyle mentioned that the age of the unit is totaly against me and also what Tom mentioned, I do feel the inside of the converter being warmer than what I am really comfortable with when I open it.  I will also try the cooling of the converter front also as it is on the floor in our bedroom and see how it reacts today, (Still Hot as He-- Out) so there should be no traffic back there to interfere with the fan.

I will connect up to only the original (30 amp) shore power and not use the dogbone (50 amp to 30 amp) idea at this time.  Seems there is no difference and could be asking for trouble if not needed to do.

The unit next to me did have problems yesterday also, they had to have the repair maintenance people come and install a new circut breaker on their power control panel, they are one of the people that has 3 big units on that beautiful 42 footer (S&S) I think you would call it.  Sure is a pretty thing.  Will take and produce photo's for you to see when I get back.  Oh well, back to my S&S.  I believe I will try and take out the Circut breaker also and try to replace it but not sure if anyone close by the campsite can replace it but will see, good project for tomorrow morning when it is cooler and I am medically well againt to do for my family when they are inside.

Man I get tired of buying someon elses problems, wonder if I will ever learn just to go get something new??  I wil keep all informed  on this board of results and do one thing at a time and record the results right to the end using your suggestions as my begining guide as of today.  This is good information for "US" newbie Electricial Tech S&S owners and good info for the bus when I get to that point.  I am sure this converter has not internal cooling source, you know how they build things for these rigs,  I guess these questions aren't as dumb as I thought as I would look to ask for everyone in my position.   

Thanks again,
Gary 
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Gary
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« Reply #7 on: August 08, 2006, 10:15:43 AM »

Gary,

The converter has nothing to do with the a/c unit other than that just happens to be where the
breakers are located. In Most S&S the circuit breakers for most of the a.c. outlets are handily located
the the same box as the 12 volt converter as a convenience thing.

They usually have a pair of 12 volt buss bars with fuses for 12 volt appliances, some are on battery full time
and some are switched to converter power when the shore cord is plugged in. The house battery charger
is in that same box and does generate a lot of heat along with the 12 volt @45 amp output converter.

Since the box gets very little air flow the cheap breakers that they use will weaken after only a few
trips and that fancy 20 amp breaker is lucky to be able to handle 10 to 15 amps.

Low voltage problems in a park will weaken an already weak breaker as the voltage goes down the
a/c compressor pulls more amperage just to keep running until it finally will stall and cause the amp draw to
go out of sight until something pops.

A roof air that is already pulling near 20 amps on a hot day might only pull 15 amps at night. This is due to head pressure
building up and causing the compressor to strain harder which uses more power.

If your voltage check shows that the voltage at the plug is below 110 volts under load and you see the voltage
run up and down as other peoples a/c units are cycling it would be a good guess that the park power system is
suffering a brown-out due to excess loading.

It's like in Wickham Park in Melbourne Fla. They have 38 campsites with 30 amp plugs but only 2ea  150 amp breaker panels
actually feeding it all. Put 15 motorhomes using up to 30 amps and the voltage goes down to crud. Breakers pop and all power quits working. The best you can get is maybe 95 volts just as the main breaker trips, Lights go out and everyone bakes...

Gary, Don't feel bad, The same problems happen in Bus conversions, we live with it or get over it or find ways around the problems.
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« Reply #8 on: August 08, 2006, 06:41:55 PM »

Gary, have you changed out your AC breaker?  New one may improve your situation.  What other 120V systems are you operating when the AC breaker fails?   120V hot water or fridge may make a difference.  May try to use LP on these items....which you may already be doing?   
Is it possible that the converter is eating too much power, some converters are right hungry.  Is there any way to turn the converter off and run house lighting and other minor 12V loads off the batts during the low voltage periods?   
Apparently newer ACs run on a good bit less amps than the older units.  I have 30 A service and can operate both of my Dometic 15K heatpumps off the 30A service with 6 or 7 amps to spare.  Have never had a problem tripping circuit breakers in the coach.   Both units running consume 22 or 23 amps when both compressors are cooling.  Nothing else is on the 30 when we're operating both ACs.   We go to a lot of campgrounds that don't offer 50A and that's the reason for my 30A choice.  LP or batts operate everything else.   The rear AC is only necessary on hot, sunny days.  Once the sun sets, I can turn off the rear AC and use the inverter/charger or save some LP if needed. 
My only management issue is Terri's hairdryer...it uses about the same amount of power as one of my ACs.   
I've got an alarm on the monitor that lets me know when over 30A is used.  Terri doesn't have the "power management" concept exactly figured out.   
See you at Timmonsville! JR
 
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JR Lynch , Charlotte, NC
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« Reply #9 on: August 09, 2006, 03:50:35 AM »

Gary,
   I did some quick calculations (this is all theorectical because I do not know how many amps your AC uses) but if your AC uses 17 amps at 125 volts, at 100 volts it would use 21.25.  If the AC is on a 20 amp breaker, you just exceeded the capacity of the breaker.  Hope this helps, Jack
« Last Edit: August 09, 2006, 03:53:54 AM by JackConrad » Logged

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Gary LaBombard
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« Reply #10 on: August 12, 2006, 09:29:53 AM »

Good Grief, I have been writing for almost an hour to repost what has happened on my S&S and wanted also to put in a photo of our trip and for some reason it all went bye bye and yes, I got ticked a little.  Imagine that!!

I am not going to retype all that I did for all that time but will condense and perhaps not put you to sleep like I normally do.  The results of the air conditioner problem of the circut breaker cutting off after a few moments is: Here is the tests done to determine what I did after betting suggestions from more experienced busnuts on this board, thanks to all again for making a good week of camping possible especially after all this darn heat this week. 

(1) Measured power at Main circut breaker in converter before activating air conditoner = (114 volts.)

(2)  Measured power at 20 amp  air conditioner circut breaker before activating air conditioner = (114 volts).

(3)  Measured power at 20 amp air conditioner circut breaker after activating air conditioner = (107.3 volts).

(4)  Removed front panel of converter control panel, it was very, very warm next to the air conditioner circut breaker in particular.  Installed a temporary 12 volt fan close to the front of the control panel, started up air conditoner after panel was cool and within a few moments the air conditioner circut breaker cut off again!! 

(5)  Determined that heat inside of converter control panel not to blame for circut breaker cutting off.  Now my thinking is Air conditoner or Circut breaker is bad.  I took the cheaper route to check first at the suggestion that the circut breaker could be bad from Tomc.  We went to ACE hardware to purchase a new circut breaker, (cost of breaker $10) with the information off the front of the original circut breaker and installed it in a matter of a few moments. 

Air conditoner worked great, it never shut off again.  It did however keep throttling the compressor on and off for 21 seconds with a 30 second interval in between day and night all the time like it had before our circut breaker breakdown.   Is this normal operation for roof airs, especially of this age, (1988, Tioga Arrow)??

Well, we had a great week and the results of this experience has me planning to do the following:

(1)  Install a 12 volt colling fan in power converter control panel to be active anytime power is supplied to converter.  This has to help in all situations of monitoring our power supply.  Infact, I plan to install all new circut breakers in power converter, if one original is bad I suspect this is a sign that all could be at a near shut down also because of use and age. 

(2)  Plan on getting a newer air conditoner, low boy when affordable considering I just put in $1600 to change over my dash air that was bad from day of purchase, (What else of coarse)!!

To newbies, If you have what you believe to be a "DUMB" question like I thought mine was and affraid to look stupid etc. never mind that worry.  Ba-- busting on this board is not tolerated and helping everyone else out with a question of any kind is the important consideration by all on this board and I am glad to have their support.  So have confidence and ask and I am sure between all inputs from reply's that you will have a good guidance to make decision from. 

Thanks again to all that replied, see you at either Timmonsville or Arcadia I hope, thanks again, have a good weekend.

I am not even going to attempt to install any photo's in this post again. 

Suggestion to Moderators, Is it possible to have your program "NOT DELETE" anything we are typing like I did unless I tell it to DELETE??  Can a modification be made so that we will not lose our information when trying to install images etc. like I tried to do after all that time of writing text??  Everyone probably would of been asleep after reading it like normally anyhow.

Gary

 
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Gary
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« Reply #11 on: August 12, 2006, 12:32:08 PM »

Gary, after experiencing a loss of a document for unknown reasons several times over the past few years, I have started typing anything that is going to be more than a few sentences into Word first.
 
I know how unhappy I have been when I have lost a long dissertation on some electrical problem and I just do not take a chance anymore. It is easy to copy and paste into the board and you can then save the writeup in My Documents in case you ever need it again.
Richard
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« Reply #12 on: August 12, 2006, 01:29:25 PM »

Good Grief, I have been writing for almost an hour to repost what has happened on my S&S and wanted also to put in a photo of our trip and for some reason it all went bye bye and yes, I got ticked a little.  Imagine that!!

<snip>
 

Gary - I am guessing that your picture was too llarge for the board limits and you got an error to the effect?  That has happened to me as well.  When this error occurs, your post is lost.  When I remember, I do a copy on the text just before I try to post so if this error occurs, I can paste it back into the form and then figure out how to resize the picture(s) to avoid the error.

Best of luck,
Craig - MC7 Oregon
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« Reply #13 on: August 12, 2006, 04:02:22 PM »

Gary,

Thank you for bringing up the "DUMB Question" point! I have always told people the only "DUMB" question is the one you wish to know the answer too but are to "DUMB" to ask for fear of looking DUMB ! BK  Grin

But then again that also reminds me of my granddad always saying "it's better to keep yer mouth shut and let folks think yer stupid, than to open yer mouth and remove all doubt!"

Don't ask me which philosiphy is correct, but then again I've never been able to keep my mouth shut either! LOL! BK Grin

Smiley Wink Cheesy It's gonna be a Blast at the "TN Fall Bus Bash" at Knuckle's check out the "TN Fall Bus Bash" Thread to see what all we got planned! Grin Shocked Roll Eyes
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« Reply #14 on: August 12, 2006, 07:51:37 PM »

Hi Gary, your comment,   "Air conditoner worked great, it never shut off again.  It did however keep throttling the compressor on and off for 21 seconds with a 30 second interval in between day and night all the time like it had before our circut breaker breakdown.   Is this normal operation for roof airs, especially of this age, (1988, Tioga Arrow)??"
would indicate a problem.  The AC compressor should run continuously during hot weather.   In cool weather it would cycle, but not that often.   Probably be ahead to replace the unit.   Doubt that a rooftop could be repaired for what one could be bought for?   
If I'm understanding that the compressor only runs for 20 seconds and off for 30 seconds, that isn't the way it should work.  Have you cleaned the air filters, condensor, and checked for anything that would obstruct airflow through the unit?  Both outside and inside.  Be careful working on the roof of a S&S...find a bad place and go right through it. 
Best, JR
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JR Lynch , Charlotte, NC
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