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PAylor

50 amp power management

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Hi all,

We have a 40 foot Augusta Ambition fifth wheel.  We have a progressive industries power management system which has a read out of power in and out.  The power is divided between two lines.  Of course we keep the power output under 50 amps.  Should we also try to keep each line under 25 amps?  On occasion one line has gone over 25 amps with no breakers blowing but I wasn't sure it was good to do.

Thanks in advance!

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If you are talking about a 50 amp campground breaker, you actually have 50 amps per leg, or 100 total. You will have to read your manual  to see if your management system can do 50 amps per leg. I know my surge guard system will handle it. With everything on, have seen 42 amps per leg [line].

Edited by jcussen

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PA, good question. I agree with jc. Typical RV pedestal "50 amp" power can supply up to 50 amps on "EACH" leg, L1 & L2, which is why a 25 amp current draw wouldn't trip a 50 amp circuit breaker. Its NOT that you have ONLY 25 amps capacity on each leg.

NOTE I'm talking about the pedestal distribution NOT anything about your power management system.

Your RV power distribution is divided up among two legs of 50 amp capacity 120 VAC which in theory is good if kept balanced so no one leg is providing ALL your needs, but just because certain loads just happen to be operating that just happen to be served by one leg isn't necessarily cause for alarm PROVIDED THAT ALL ELSE AND THE DISTRIBUTION SYSTEM IS DESIGNED AND OPERATING CORRECTLY.    

I make no comment on the capacity of your power management system and if it can handle 50  amps per leg etc., but its good and safe to be aware of and concerned with power use and how its divided (hopefully somewhat balanced to some degree) in your rig.

PS is this what you have ???  http://tweetys.com/electrical-management-system-hardwire-50.aspx

John T   Longggggggggggg retired and rusty electrical engineer so NO warranty

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18 hours ago, PAylor said:

Of course we keep the power output under 50 amps.  Should we also try to keep each line under 25 amps?  On occasion one line has gone over 25 amps with no breakers blowing but I wasn't sure it was good to do.

If you examine the circuit breakers either for main power in the RV or at the power pedestal, you will find that it is actually 2 separate circuit breakers of 50a each and one passing one leg of the power supply. The two breakers are mechanically linked so that should either one experience more than 50a it will cause both to open. 

siemens-2-pole-breakers-q250h-64_1000.jp

This means that in theory, you could use up to 100a of 120v electric power but since to do so each leg would have to see exactly 50a, the real world is that you probably have about 80a of total useful power available. It is very rare for any 50a rated RV to have problems tripping circuit breakers for the main power. But there is no need to set a 25a per leg limit as the limit is for each of the two legs. That does mean that when compared to the typical 30a RV you have far more than twice the power available but in fact, it gets very close to 3 times as much available power.

There is a lot of electrical theory involved in this but there is really no need for long discussions for the average RV owner. In practical application, the 50a RV cord actually has two power leads in it, each of them rated to supply a maximum of 50a and each one with a circuit breaker that will shut off all power. 

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Good info and picture Kirk. Indeed the two breakers, one for L1 other for L2, are for safety and/or other possible reasons mechanically tied together so if one opens the other does also. In many years of practice I've even seen where an "electrician" ? used a piece of wire through the handles (if not otherwise tied) to join two breakers.  While a professional electrician tech or engineer is well aware of what you so well described, if they were NOT tied a lay person or many typical RV owners might encounter a hazardous situation otherwise YIKES...........   

Best wishes Kirk and all here, be safe now

John T

 

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Paylor,

 You have an electrical management system.  Let it do its work.  The only time you should have to pay any attention to the loads is when you only have 30 amp available (older parks, etc.).   Then you will quickly learn how to balance and work with that limitation (only one significant draw on at a time).  But on '50 amp' power at the pedestal (which is really 100 amps as you see) unless you are paying for electric for the site, just go about your daily activities.

Barb

 

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what we did do when we ordered this 5th wheel was to make sure the  load on the legs were evenly distributed that is one A/C on each leg not both on the same leg etc. We  are nearly always on 50 amps and have never had a load issue on either leg. We do pay for our electric here on our Florida site and we use what we use. 

Edited by richfaa

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3 hours ago, richfaa said:

one A/C on each leg not both on the same leg etc

That's a for sure Rich. The AC is one of the heavier current loads in an RV and its always best to balance loads (like L1 & L2 in a 50 amp RV) and to reduce current flow (wasted I Squared R losses) in the grounded conductor when possible.

I'm on the way to Florida to join you right now, it turned cold in North Texas and South Louisiana where I'm at a Walmart tonight brrrrrrrrrrrrrrrrrrrr

John T 

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Well,  I cannot remember seeing a 50 amp RV wired with the AC on the same leg of service (when having only 2 AC units). And I've worked on RV electrical in countless rigs. Now everyone can tell me all the ones they have seen wired that way..... :) Seriously, I'd like to know if people see that often...because I sure have not. Vern???

 

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15 minutes ago, Jack Mayer said:

Well,  I cannot remember seeing a 50 amp RV wired with the AC on the same leg of service (when having only 2 AC units). And I've worked on RV electrical in countless rigs. Now everyone can tell me all the ones they have seen wired that way..... :) Seriously, I'd like to know if people see that often...because I sure have not. Vern???

From the factory not likely but one should confirm that. After market it happens.There are other high draw appliances that need to be checked.Hot water tank, MW, Etc and I said evenly distributed and used the A/C as a example should have known better on this forum.

 

what we did do when we ordered this 5th wheel was to make sure the  load on the legs were evenly distributed that is one A/C on each leg not both on the same leg etc. We  are nearly always on 50 amps and have never had a load issue on either leg.

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1 hour ago, Jack Mayer said:

Seriously, I'd like to know if people see that often...because I sure have not. Vern???

I can't remember having ever seen one connected that way. It would be noteworthy poor design to do that.  

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2 hours ago, Jack Mayer said:

Well,  I cannot remember seeing a 50 amp RV wired with the AC on the same leg of service (when having only 2 AC units). And I've worked on RV electrical in countless rigs. Now everyone can tell me all the ones they have seen wired that way..... :) 

SAME HERE JACK, as a 47 year RV user and past RV dealer if a 50 amp RV has two AC units they were on two different legs, despite that I learned to NEVER SAY NEVER lol

John T

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6 hours ago, oldjohnt said:

as a 47 year RV user and past RV dealer

Good grief! You must be even older than I thought! :P

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5 hours ago, Kirk Wood said:

Good grief! You must be even older than I thought! :P

Hey Kirk, you rascal you, I resemble that remark LOL The "first wife"  (I still call her that)  and I bought our very first "RV" in 1970, it was home made, bought on the south side of Indianapolis, and it fit on the back of our old Ford 4 x 4 pickup which we drove to Florida and hauled my Uncles boat back home, we came a long way since but a person never forgets their first unit and how I fixed it up and the fun we had.... The dog we took along with us died but the wife and I survived............

Best wishes

John T

Edited by oldjohnt

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