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06-21-2009, 03:14 PM
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#1
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Montana Master
Join Date: Jul 2005
Location: Fort Myers
Posts: 5,933
M.O.C. #4282
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Disappearing voltage?
Don't recall seeing any topics on this ever. Hopefully someone can help. I have a Kill-A-Watt meter that I monitor my CG voltage with.
This past weekend, I was hooked up to 30 amp service at an older CG and it started out at 115 volts. I turned on my main AC and the volts dropped to 108. Low, but not below the 102 threshold that autoformers/surge protectors usually try to take evasive/corrective action.
After about 45 min, the unit started to sound funny. I got up and looked at the volts and it was down to 95. I immediately shut down the AC. I was not happy.
Before leaving today I tried the AC again and I was surprised and greatly alarmed as I watched voltage slowly drop from 108 to 104 within 20 minutes. I again shut it off.
I came home this afternoon and hooked up the 3400 to an HD 15 amp extension cord from the house and I shut everything else off in the Montana. I read 121 amps. I turned on the AC. When it came on the volts dropped to 106. I sat and watched the meter as it gradually, slowly started dropping a little at a time.
After 10 minutes it was down to 104.5 volts. After 20 minutes it had slowly drifted down to 102. When it hit 101.5 at 30 minutes, I shut it down.
What is up with my disappearing voltage???
I also have not tried my 2nd AC, or any other appliance. I can do that experiment tomorrow.
* PLEASE NOTE: This topic is NOT a question of the pros/cons of surge protectors/autoformers. So please refrain from opinons drifting off topic in that direction. Thanks in advance.
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06-21-2009, 03:38 PM
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#2
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Montana Fan
Join Date: Oct 2006
Location: East Moriches
Posts: 418
M.O.C. #6436
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I would start by checking the circuit breakers, both the main and the ac breaker for tightness (loose connections can build up heat and cause a voltage drop). I also would check the neutral for tightness (same reason). Also at the CG outlet you could have had a loose connection, and if the extention cord at home was too long that could give you a voltage drop by overheating. Good luck in your trouble shooting. If i can offer additional help post it or PM me.
John
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06-21-2009, 03:59 PM
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#3
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Montana Master
Join Date: Jul 2005
Location: Fort Myers
Posts: 5,933
M.O.C. #4282
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Thanks, John. I was wondering about the heat. The ext cord at home is single 100' cord (twice what I actually need). And it was in the 80's this afternoon. A loose connection at the CG pedestal is also a possibility, but the same behavior at the CG and home might eliminate this as a culprit?
I have pulled my panel and checked all connections for tightness, but that was 2 yrs ago. Can't hurt to pull the panel again.
Also, my neighbors were having some minor problems with their electricity also. New Cougar next to us had it's microwave making strange noises and my other neighbor thought their coffee maker was acting funny.
If I had a loose neutral in my Montana, could that cause problems for my neighbors - just curious?
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06-21-2009, 04:07 PM
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#4
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Montana Master
Join Date: Jul 2005
Location: Fort Myers
Posts: 5,933
M.O.C. #4282
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Also, not sure if this is helpful but an example of the voltage drop was as follows...
106.5... 106.4... 106.6... 106.3... 106.5... 106.4... 106.2... 106.3... 106.2... 106.0... 106.1... 105.8... etc, etc, etc.
Slightly fluctuating while slowly dropping.
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06-21-2009, 04:32 PM
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#5
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Montana Fan
Join Date: Oct 2006
Location: East Moriches
Posts: 418
M.O.C. #6436
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If you had a loose neutral in your montana it would only affect you. The dropping voltage sure sounds like a loose connection somewhere. As a second test I would leave the ac off and run the microwave and other loads to see if the voltage drop occurs without the ac on. I also would get the shortest 12 gauge extention cord and use it instead of the 100 foot one. Again good luck.
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06-21-2009, 04:44 PM
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#6
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Montana Master
Join Date: Jan 2003
Location: Haldimand County
Posts: 2,413
M.O.C. #122
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Take a good look at your connecting cable(s). Any chance they are corroded and causing a poor connection that gets worse the longer a heavy load is applied (i.e. is the plug getting hot?)
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06-21-2009, 05:16 PM
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#7
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Seasoned Camper
Join Date: Sep 2006
Location: Springfield
Posts: 81
M.O.C. #6238
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As your A/C runs in hot weather the pressure increases and the unit pulls higher amps, this will drop your voltage.
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06-21-2009, 05:21 PM
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#8
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Montana Master
Join Date: Jul 2005
Location: Fort Myers
Posts: 5,933
M.O.C. #4282
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Come to think of it, when I had my wife run around the back of the house and plug in the extension cord, she complained that she got sparks from the outlet. I dismissed it, but now that I think about it, she was adamant about it. There might be a problem somewhere in my rig. There should be no sparks when that ext cord is plugged in. Maybe make a slight sound, but she may have gotten way more than she should have. I will talk to her in the morning - she's sleeping now - and then I will check on it myself tomorrow.
The only things online were the fridge and the converter when she tried to plug the rig in... Also the CO2/smoke/propane detectors...
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06-21-2009, 05:24 PM
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#9
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Montana Master
Join Date: Jul 2005
Location: Fort Myers
Posts: 5,933
M.O.C. #4282
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Quote:
quote:Originally posted by robb
As your A/C runs in hot weather the pressure increases and the unit pulls higher amps, this will drop your voltage.
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The first time this happened in the CG, it was around 70° and 10 pm. It was very humid out and I was just trying to dry out the air in the Montana a little, so not sure this was an issue - for that time, anyway. However, this is a good point.
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06-22-2009, 12:02 AM
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#10
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Montana Fan
Join Date: Oct 2006
Location: East Moriches
Posts: 418
M.O.C. #6436
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David,
If you have anything on in the trailer when you pull out the extention cord it will spark. this is normal (not good but normal). The more current you draw the bigger the spark. You should turn the CG breaker off any time you plug in or unplug the trailer. If your wife said it was a big spark other loads could be on that you are unaware of, (water heater etc.). Also ask her if the plug was hot. Good luck in your quest.
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06-22-2009, 02:31 AM
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#11
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Montana Master
Join Date: Feb 2003
Location: Englewood
Posts: 3,095
M.O.C. #164
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We camped in an older Camp Ground for years when it was hot and Air Conditioners were coming on the voltage dropped into the low 90's
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06-22-2009, 04:16 AM
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#12
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Montana Master
Join Date: Aug 2007
Location: Waterford
Posts: 3,693
M.O.C. #7500
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There is a series of equations called "Ohm's law" that explain the relationship between voltage, current and resistance. Voltage = V, Current (also known as Amps) = I and Resistance = R. For resistance, think of the effort the electricity has to take to complete it's circular route from the power source (where you plug in at) and back again. Anything that impedes this effort is resistance. Things that will impede are: long extension cords, smaller wires in extensions cords and the amount of power needed by the device you are operating - in this case an air conditioner. As already stated, your long extension cord coupled with the higher working load of the air conditioner due to the outside heat, will cause more resistance than if you were using a shorter/heavier cord and/or the outside temps were cooler.
The equation works as thus:
Voltage = Amps x Resistance or V=IR
In your case, as your resistance increased, the amperage decreased because resistance controls the flow of amps. This is confusing for some folks as they think when they blow a fuse, the load was too high. Actually what happens is the resistance was too low - as in a short - and causes high amps to trip the fuse/breaker. But I digress. When the resistance increases, it decreases the amperage, and since voltage must equal the amperage x resistance, the voltage falls. If it were a perfect world and amps declined at a rate equal to the resistance increase, the voltage would remain the same, but it's not a perfect world.
So, your voltage isn't disappearing, it's being consumed by the excess resistance. If the voltage at the plug in was lower than 110 to begin with, then you also have a resistance problem before the plug, something that happens when old campgrounds used too small of wire to run to the sites.
Hope this helps!
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06-22-2009, 06:37 AM
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#13
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Montana Master
Join Date: Apr 2007
Location: South Shore
Posts: 6,009
M.O.C. #7110
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Quote:
quote:Originally posted by Tom S.
There is a series of equations called "Ohm's law" that explain the relationship between voltage, current and resistance. Voltage = V, Current (also known as Amps) = I and Resistance = R. For resistance, think of the effort the electricity has to take to complete it's circular route from the power source (where you plug in at) and back again. Anything that impedes this effort is resistance. Things that will impede are: long extension cords, smaller wires in extensions cords and the amount of power needed by the device you are operating - in this case an air conditioner. As already stated, your long extension cord coupled with the higher working load of the air conditioner due to the outside heat, will cause more resistance than if you were using a shorter/heavier cord and/or the outside temps were cooler.
The equation works as thus:
Voltage = Amps x Resistance or V=IR
In your case, as your resistance increased, the amperage decreased because resistance controls the flow of amps. This is confusing for some folks as they think when they blow a fuse, the load was too high. Actually what happens is the resistance was too low - as in a short - and causes high amps to trip the fuse/breaker. But I digress. When the resistance increases, it decreases the amperage, and since voltage must equal the amperage x resistance, the voltage falls. If it were a perfect world and amps declined at a rate equal to the resistance increase, the voltage would remain the same, but it's not a perfect world.
So, your voltage isn't disappearing, it's being consumed by the excess resistance. If the voltage at the plug in was lower than 110 to begin with, then you also have a resistance problem before the plug, something that happens when old campgrounds used too small of wire to run to the sites.
Hope this helps!
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This is very good information.
Thanks for sharing!
__________________
2011 GMC 4X4 dually CC, 6.6 Duramax with Allison Transmission. Formally 2001 Montana,2007 3400RL Montana, presently 2018 3401RS Alpine.
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06-22-2009, 06:43 AM
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#14
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Montana Master
Join Date: Aug 2007
Location: Waterford
Posts: 3,693
M.O.C. #7500
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Yeah, sometimes people ask me what time it is and I tell them how to build a clock! Glad to 'help'!!
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06-22-2009, 07:07 AM
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#15
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Montana Master
Join Date: Jul 2005
Location: Fort Myers
Posts: 5,933
M.O.C. #4282
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Very good, Tom!
I just went out and ran my 2nd AC in the 3400. Same problem - showing 121.3 before running - 108.4 (This in itself seems a significant initial drop to me) when initially switched on (Low/AC on this 13.5K Low Profile, non-ducted unit). In 4 minutes it slowly dropped - with slight fluctuations - to 104.9 at which point, that was all I needed to see and I switched it off.
It is currently 85 and humid outside, which makes it difficult/impossible to work inside the Montana w/o AC. I will try to pull that panel and look and the wiring as soon as possible.
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06-22-2009, 07:39 AM
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#16
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Montana Master
Join Date: Oct 2008
Location: Siloam Springs
Posts: 2,206
M.O.C. #8890
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Do you turn off the outside electrical switch on the hot water heater before turning on the AC when connected at home.
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06-22-2009, 07:51 AM
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#17
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Montana Master
Join Date: Jan 2005
Location: North Ridgeville
Posts: 20,229
M.O.C. #2839
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Dave... Don't think you have a problem. TomS gave a good explaination. When you are on a good 50 amp ckt you will be good. Have seen that at older C.G's
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06-22-2009, 08:44 AM
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#18
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Montana Master
Join Date: Jan 2003
Location: Haldimand County
Posts: 2,413
M.O.C. #122
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Can you plug your voltage tester into a U-ground 120 volt on the power pole? If so, that may help determine if the voltage drop is in your wiring or the park's. If you see the same sort of voltage drop on the power pole, then it is the park's problem, and there is not much you can do about it. If the voltage holds at a normal level on the power pole, then look for a problem in your wiring. If any of your plugs look corroded, try cleaning them up with some metal polish or very fine emery paper. I would start at the power pole and work towards the trailer until you find the source of the problem. As others have suggested, there are several possible causes for what you are reporting.
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06-22-2009, 11:37 AM
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#19
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Montana Master
Join Date: Jul 2005
Location: Fort Myers
Posts: 5,933
M.O.C. #4282
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Thanks, guys. Very helpful info and advice. I am looking at ordering a 50 ft (just the right length) 12-3 extension cord from Home Depot. $42.00. The 14-3 cord - same brand - is about half of that. I believe for our Montanas, that 12-3 is worth the extra $$.
BTW, My hookup consists of my outdoor outlet on my house with the 100 ft 16-3 cord. The adapter is the 50 amp to 15 amp adapter (think this came with my 3400 when I bought it...) and then the 50 amp cord into the rig.
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06-22-2009, 11:46 AM
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#20
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Montana Fan
Join Date: Oct 2006
Location: East Moriches
Posts: 418
M.O.C. #6436
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Just remember that the outlet on the house is not the starting point. There is possibly another 100 feet or so of 12/2 wire inside the house to get to the circuit breaker. All that also adds to voltage drop.
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