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Protagonist · 07-08-2013, 10:50 AM

Quote:

Originally Posted by markdoane

No. Each hot leg should provide 50 amps.

Neat way to get 100 amps out of a 50-amp circuit!

If the current on the municipal side of the breaker panel is 50 amps on one 240-volt circuit, then it still has to be 50 amps total on two 120-volt circuits on the other side of the breaker panel, or 25 amps per 120-volt circuit.

I'm not an electrical expert. I walked two cubicles down from where I work and asked a registered professional electrical engineer, and that's what he told me. I don't think he's wrong. Since I'm not an expert, I'll bow out now and let the discussion continue without me. Don't want to disrupt my coworker's schedule to have him answer more questions.

47WeeWind · 07-08-2013, 10:50 AM

Buy, read and keep this book in your trailer:
Managing 12 Volts: How to Upgrade, Operate, and Troubleshoot 12 Volt Electrical Systems by Harold Barre (2nd Ed., Jun 2002)

PharmGeek · 07-08-2013, 10:55 AM

Inded, thanks Protaganist...I will get it and read - sounds like its up the alley that I am looking for.

**DKB_SATX** · 07-08-2013, 10:56 AM

Quote:

Originally Posted by Protagonist

Neat way to get 100 amps out of a 50-amp circuit!

If the current on the municipal side of the breaker panel is 50 amps on one 240-volt circuit, then it still has to be 50 amps total on two 120-volt circuits on the other side of the breaker panel, or 25 amps per 120-volt circuit.

I'm not an electrical expert. I walked two cubicles down from where I work and asked a registered professional electrical engineer, and that's what he told me. I don't think he's wrong.

50A x 240V = 12,000 watts.

50A x 120V = 6,000 watts, x2 = 12,000 watts.

A pair of 50A 120V circuits delivers the same as a single 50A 240V and energy has neither been created nor destroyed...

Protagonist · 07-08-2013, 11:01 AM

Quote:

Originally Posted by DKB_SATX

50A x 240V = 12,000 watts.

50A x 120V = 6,000 watts, x2 = 12,000 watts.

A pair of 50A 120V circuits delivers the same as a single 50A 240V and energy has neither been created nor destroyed...

Guess I'd have known that if I looked it up in the book I recommended, but I'm at work, the book's at home, and my colleague may not have made his explanation idiot-simple enough for me so I misunderstood what he told me. That's the problem when talking to engineers, they automatically talk to you as if you know what they're saying.

I stand corrected.

Silverflames · 07-08-2013, 11:19 AM

Ok to be clear... As mud.. 50 amp service at camp grounds, each leg provides 50 amps? Not 25 amps?

So you are really getting 50 amp and 50
Amp hot lines, with a total access to 100 amps of power??

So that would require at least 6 gauge wires...

**DKB_SATX** · 07-08-2013, 11:23 AM

A Marinco 25 foot 50A shore power cable has 3 6-gauge conductors and one 8-gauge, apparently.

Marinco ParkPower 50A cable

And yes, 100A at 120V is the same amount of power as 50A at 240V.

Silverflames · 07-08-2013, 11:31 AM

That's a lot of power. So when you go from a 30 amp system to a 50 amp system, you are really getting access to 70 more amps..

richinny · 07-08-2013, 11:37 AM

there are a lot of threads like this. this is one of the recent ones:
http://www.airforums.com/forums/f37/...ce-105528.html

perryg114 · 07-08-2013, 11:52 AM

All you need is a 30A 120V single pole breaker with #10 wire going to your trailer with and 120V female RV plug on it. This will power one AC unit which will be plenty in Alabama with the unit covered or even out in the sun with the shades drawn. Is your trailer wired for 50A as well? If you are going to use it as a spare bedroom and you want all the facilities at 100% then put in a 50A service if it is wired for it. You will also need water and sewer. 50A will get you 50A on both hots wires so you have two 120V 50A power sources. Which is 12,000 W and standard 30A connection is 3600W. You can be a power hog with 50A if you are wired for it.

Don't get your local power company involved if as all possible. They will want you to upgrade your home service to 300 or 400A and then your whole house will have to be brought up to current electrical codes. Yes it is a racket run by your local electrical union.

Perry

PharmGeek · 07-08-2013, 12:12 PM

I am not entirely sure if mine comes with 50 amp plug - with two ac units stock, I am thinking it will...but not actually sure at this moment.

Richinny, thanks for that link....although I am not sure that I am clear on the best answer to their question...

Seems like to me that running from 50a source and using 50-30amp dog bone will leave 50amps running through a 30amp rated cord...thus possibly excessively heating that cord?

On the other hand, some folks complained about the condition and "overuse" of the 30amp source at campgrounds and have heated up their connections when running say their heater...and they supposedly fixed this problem by doing the dog bone 50-30amp route....

I am a bit confused as to why the 30amp service would cause overheating of the plug? That is this issue of previous "over-use".

Also, do these AS's new come with quality integrated surge protection in the event of surges of various kinds? Or is it a good idea to use something out where you hookup as well?

PharmGeek · 07-08-2013, 12:14 PM

I spoke with one of the forum members via phone...helped really explain alot of the basics of operation here...huge help.

I think I entirely understand the contractors confusion.....he seems to not understand that all of the A/C appliances in the AS are 120v jobs...I explained to him the 50 amp RV connection - the two 120v legs (and as I understand it has a ground and a dummy in addition?). His reponse: "ok"

perryg114 · 07-08-2013, 12:58 PM

The 50A plug has an extra pin. A trailer wired for 30A will have a 30A breaker to protect the cord. I am not sure how a trailer wired for 50A would work on a 30A system. I would think that the breaker panel would have a switch for 50A 220V input or 30A 120V input. Everything in the trailer is 120V but the way it is divided can be important with downgrading to 30A. Most likely a trailer wired for 50A would have a main 220V 2 pole breaker rated at 50A. I expect that if most new trailers come with a 30A system then adding an extra AC unit would mean the second AC would be on the second 50A 120V circuit and nothing else. I would talk to the dealer you ordered the trailer from or better yet the factory. I don't know how they deal with switching back and forth between 30A and 50A services. It may also be possible that your trailer only used 30A on each circuit in which case you would have the 30A main breaker no matter how it is wired. Lewster on here may have the answer since he is a dealer.

Perry

PharmGeek · 07-08-2013, 01:02 PM

ill message my dealer as well...I have a few questions for AS directly as well anyway otherwise.

TG Twinkie · 07-09-2013, 07:46 AM

Most panels, even on a 30 amp service are split buss. That is why there is a jumper across the main lugs.
A 30 amp 120 volt service is a 3 wire system.
A 50 amp 120 volt service is a 4 wire system. All 120 volt devices are connected thru circuit breakers to one or the other hot leg and the neutral.
Nothing in your trailer will require connection between the 2 hot legs. Which is 240 volts.
If you have 2 air conditioners, one should be connected to one hot leg and the neutral, the other to the opposite hot leg and the neutral. To balance out the load.
Make sure your electrician understands what must be done to wire the outlet and the trailer if you upgrade to 50 amp.

PharmGeek · 07-09-2013, 08:09 AM

yes after talking via phone with a couple folks including lewster...it is quite clear.

the real doomsday scenario is a 30amp 240v. receptacle and plug RV into that.....NOT GOOD...

I re-iterated to my contractor that NONE of my appliances combine 120+120...they are simply 120....and interesting, after discussing via phone, the 220 dryer in the house takes two 120v legs and within the appliance, combines it...

A 50amp 240v receptacle that has the same prong arrangement as the RV 50amp plug from my trailer (three verticle slots on top, one round below im told) will indeed do the trick...

lsbrodsky · 07-09-2013, 09:54 AM

Your use of " in the appliance, combines it" emphasizes that you do not understand electricity, but are repeating what others have said. Look, electricity can kill you. The safest thing for most is to buy a simple plug in polarity tester at Lowe's and a 30-20 adaptor, plug in to the campground AC and if the lights are on, just plug in your trailer. If you are getting a 50 amp trailer, that won't work. Trust the campground or learn to use a voltmeter on the appropriate pairs of the outlet.
If you go to major campgrounds just trust them. Just let electricity be a mystery and stay alive.
Larry

SteveSueMac · 07-09-2013, 10:34 AM

Quote:

Originally Posted by lsbrodsky

Look, electricity can kill you. The safest thing for most is to buy a simple plug in polarity tester at Lowe's and a 30-20 adaptor, plug in to the campground AC and if the lights are on, just plug in your trailer.

Not to hijack this thread, but as someone who barely knows positive from negative, I do know that your warning about electricity is worth heeding.

I found this description on line and wanted to know if this is the kind of setup you're talking about: http://www.myrv.us/electric/Pg/tester_30amp.htm

Knowing myself as I do, I'm not ashamed (or insulted) to admit I need an IDIOT-PROOF way to test for all the things I should at the campground. Last weekend was the first time we experienced tripping the breaker at the campground pole (not internally to the trailer but externally at the power supply from the camp ground). We've had AC and other electric appliances on at the same time before but never tripped a breaker.

What specifically would the setup above cover (not clear on the 3 circuit piece he plugs in as well??). Is that sufficient? Anything missing? I realize that's just to test - surge protection would be a different category...

Thanks!

lsbrodsky · 07-09-2013, 10:45 AM

The plug on the right and the yellow polarity tester are all you need to check any 30 amp safe for your trailer. Just plug it in look for the correct lights, unplug it and plug in you shore power cable. I have done something similar at marinas for 30 years.
It is not going to tell you whether you draw too many amps for an inadequate shorepower service, but with a normal campground 30 amp and a stock trailer that should not be an issue.
Larry

SteveSueMac · 07-09-2013, 10:57 AM

Quote:

Originally Posted by lsbrodsky

The plug on the right and the yellow polarity tester are all you need to check any 30 amp safe for your trailer. Just plug it in look for the correct lights, unplug it and plug in you shore power cable. I have done something similar at marinas for 30 years.
It is not going to tell you whether you draw too many amps for an inadequate shorepower service, but with a normal campground 30 amp and a stock trailer that should not be an issue.
Larry

So just to be clear - the box on the right tells you within a certain safety range (that green zone) whether the camp is providing enough voltage. And you're saying the yellow box on the left is telling you about the "polarity" meaning whether the wires are hooked up correctly? And I assume then that the first 2 should light up and the 3rd being off is a good thing? Apologies for being so elemental about this but I agree - electricity can kill and while I'm content to let it be a mystery, I'd like to know enough about a simple testing process that can reduce fatal or expensive mistakes...thx!!