chiefnolan

Coverting Coach From 30amp to 50amp

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So if I plug my 50 A cord into a 30A adapter then into a 30A pedestal   I will not have 2 30A 120VAC lines I will have 1 30A 120VAC and half the circuits in my unit will be dead. So I should avoid like the plague any space with no 50A service. 

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bm02tj   

when you plug your 50 amp into a 30 amp adaptor you have 30 amps to feed what would be 100 amps with the 50 amp service as it joins the two legs 

that is why nothing runs on 240 volt as your house would  

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Just to clarify, if plugged into a  30A service it will be necessary to monitor what is using power so not to have a brown out, and damage components.

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bm02tj   

yes you are limited to 30 amp total  and should only use 85% to stay safe and not hurt anything or blow the breaker and have to go out to reset 

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7 hours ago, rhinderber said:

So if I plug my 50 A cord into a 30A adapter then into a 30A pedestal   I will not have 2 30A 120VAC lines I will have 1 30A 120VAC and half the circuits in my unit will be dead. So I should avoid like the plague any space with no 50A service. 

This is not correct.  All of your circuits will still work if you plug a 50 amp coach into a 30 amp plug.  You just need to monitor your total AC usage to ensure that all combined circuits do not exceed 30 amps.  In a 50 amp coach you have 2 50 amp circuits or a total of 100 amps available.  When you plug into the 30 amp plug, everything still works but you are limited to a total of 30 amps.

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Okay, this works for me and any combination should work for others, just need to monitor current load.  In my case the Electrical Management Syste (EMS) does that.

When I park in covered storage I have 120V 20A available.  My MH plug is 50A (Four pins). I plug a 12 gauge short extension cord into the 120v supply into a 30A to 15A Adapter  plug (20A to 30A in reverse direction) Th 30A Adapter plugs into the 50a to 30A Adapter (reverse is 30A to 50A) and the motor home 50A  Adapter plugs into the 50A to 30A Adapter.  All of these adapters are available at Walmart, Target, and other stores and RV supply houses.

So it is MH plug into 50 to 30, and 30 into 30A to 15A. Two Adapters for just about any configuration. Absolutely necessary to monitor current when using anything less than 50A

Links to what the adapters look like.

50 to 30A Adapter

30 to 15A Adapter

My EMS will automatically run 1 AC pump on 15A but I best not turn to many other items on.

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TBUTLER   

Well said Bill and Wayne.  I saw that posting yesterday and put it on my to-do list to clarify how things work when on limited electric.

We have stayed in our motor home for extended periods at my mother's home.  We were plugged into a 20 amp outlet in her garage, similar to Wayne's solution except I had a single adapter to go from 50 amp to 20 or 15 amps.  Our EMS (Intellitec) has a button to select 20 amp service.  It automatically senses the 30 amp connection, press the button and it sets itself to 20 amp.  And, yes, you can run a single air conditioner on a 20 amp or even 15 amp connection. 

The owners manual for our motor home had a complete listing of the electrical equipment and appliances in our motor home.  It listed the amperage of each device.  When we moved into the motor home Louise and I had a sit down session discussing the list and electrical management.  She is a quick study, we've had few problems living with limited electric.  We always prefer 50A service but don't hesitate to use 30A.  In fact, if you travel in Canada you will probably not find 50A service available at most campgrounds.

By the way, you really can't damage anything by using the electric right up to popping the breaker.  It is just a matter of resetting the breaker.  The greatest danger to the electronics in a motor home is low voltage.  That is caused when the wire supplying current is smaller than needed to deliver the amperage of the breaker.  Long runs of wiring require using larger wire than for short runs.  A #10 wire works for 30A current but if you run it 200 or 300 feet to get to the post (common in RV parks), you must us #8 wire or even in really long runs a #6 wire.  The same is true with the 20A examples above.  If you use a household extension cord, less than #12 wire, you will experience low voltage as you approach the 20A limit.  When the voltage drops below 100, electrical components and motors in the motor home can be damaged and may fail.  A good plug in voltage meter will help you monitor your electric supply if your coach doesn't already have some way to monitor the voltage of the electrical supply.  A good surge protector usually will also detect and shut down when voltage drops too low.  A 50A surge protector will detect low voltage even when plugged into a 20A source.  Another good reason to have a surge protector on your incoming electrical supply cord.

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manholt   

Wayne.  In my storage garage, I have the same set up.  I use the available 20A to run my residential fridge and a trickle charger for my engine batteries!  :P 

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jrock   

 When you plug into a 50 amp shore power you do not have 100 amps total you will only be able to draw 50 since the breaker is only 50 what happens on a 50 is if one leg is using more than the other the difference goes to the neutral conductor so if L1 is 20 amps and L2 is 10 amps 20 amps would be on L1 and L2 and the neutral would carry 10 amps if the load was balanced the neutral should be 0 max continues load should not exceed 80 % of the breaker rating per national electric code if you go over 80% the breaker could eventually overheat and trip on thermal you don't always have to exceed full rating of breaker to have it trip the advantage is that with a 120/240 volt supply you do have more total wattage available 

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wolfe10   

John,

Not sure I understand what you are saying.

If the outlet is 50 amp and the coach is 50 amp, you DO have 100 amps available. A 50 amp outlet has two 50 amp breakers pinned together. So up to 50 amps on L1 and 50 on L2.

You are correct, the neutral only carries the DIFFERENCE between load on L1 and L2.

Indeed, if the coach is only wired for 30 amps, whole different ball game.

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jrock   

Brett you don't add the 2 legs together they are only 50 per leg the both legs are pined together because if one side overloads code says both have to open together even if the other is ok

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wolfe10   

John,

Agreed, if more than 50 amps (or even very close to that for long enough to overheat the breaker) is demanded of either leg, both breakers will trip.

But, don't want to confuse here:  50 amp RV service is 100 amps @120VAC.

Here is a good link: http://www.myrv.us/electric/Pg/50amp_Service.htm

Second paragraph: Each leg is 50 amps @ 120 volts. 50-amp X 120-volt = 6000 watts But since there are 2 HOT 120-volt  legs at 6000 + 6000 = 12,000 watts to use in the RV...

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6 hours ago, jrock said:

Brett you don't add the 2 legs together they are only 50 per leg the both legs are pined together because if one side overloads code says both have to open together even if the other is ok

To the very slightest degree, this is correct.  If you exceed 50 amps on any 1 leg the breaker will trip cutting power to both legs.

However, you could use 40 amps on one leg and 40 amps on another leg without causing any issues with the 100 amp service available.  For some period of time you could use 50 amps on both legs and the breaker should still hold but I really don't recommend this!  Over 50 amps on either leg and the service is going down.

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jrock   

Bill you will not draw 100 amps you do not add the 2 poles together you will have more capacity if the pedestal is correctly wired  because you have 2 legs that are 50 ea either leg gets to 50 breaker trips you can not draw more than 50 on either leg if you don't believe me get hold of a 240 volt load bank and prove it for yourself

100 amp is coming not to far out power cord for that will be like a fire hose 

240v x 50a = 12000 watts

L1 120v x 50a = 6000 watts

L2 120v x 50a = 6000watts 

total for 1 & 2 is 12000 watts  max continues load at 80% = 9600 watts or 40 per leg if you exceed this the breaker will start to heat up and eventually open on thermal load  most problems are due to old outdated wiring in park systems and ther fear their ugly head when the temperature goes up and air conditioning load is up 

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TBUTLER   

OK, if one leg exceeds 50A, you will trip the breaker, cutting off both lines.  But up to 50A per line, you are good.  I'm certain there are coaches that might exceed 50A per line but our coach would never make it unless I start plugging in electric heaters.  I do sometimes push a 30A breaker to 28 or 29 amps and if the breaker is good and the line is good, it is no problem.  In fact recently I was on a 30A line using 18A when the second air conditioner kicked on.  I happened to be looking at the amperage at the time.  For about 3 seconds we were pulling 34A and the breaker didn't trip. 

John is correct, the wiring must be adequate to supply 110/120 V per line at 50A.  Older parks with inadequate wiring will limit the usable amperage you can draw.

I am puzzled as to what exactly these statements mean, " 100 amp is coming not to far out power cord for that will be like a fire hose" and "and ther fear their ugly head when the temperature goes up and air conditioning load is up"  I always try to re-read what I've typed before sending and correct mistakes if there are any.  Just a friendly suggestion.

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jrock   

Tom i guess it was a bad attempt at trying to be funny  I was told by the owner of a park I have worked at that 100 amp shore power will be coming in the future that means you will have a 2 pole 100 amp breaker and the power cord feeding the coach will be much larger 

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John,

I am still unsure your information is helping anyone understand the difference between 30 amp and 50 amp coaches.  The "theoretical" amount of power available to a 30 amp coach is 30 amps.  The amount of power available to a 50 amp coach is 100 amps (50 amps on each leg).  That's a huge difference between the way the 2 coaches are wired.

This does require the 50 amp RV to be plugged into 50 amps service.  This service has 2 50 amp breakers with a bar connection so that if one trips they both trip.  It also requires the park run the correct sized wiring to the pole and the RVer use a cord rated for 50 amp service.  This is a fat cord and normally contains 3-#6 wires plus 1-#8 ground wire.

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jrock   

 Bill look at it this way 30 amp service = 3600 watts 50 amp service = 12000 watts so you have 3 times the power on a 50 

the link I put on last post explained it better than I can  

in a house you have a 2 pole 100 amp main breaker you don't call that a 200 amp service it's 100 

same in a rv a 2 pole 50 amp main breaker is a 50 amp service

I'm done maybe an electrical engineer can chime in 

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wolfe10   

Yes, think this thread has run its course.

We all agree:

30 amp RV power provides up to 30 amps of 120 VAC.

50 amp RV power provides up to 100 amps of 120 VAC.

And, that on older set ups with smaller gauge wire, worn breakers, etc, one may not be able to draw the full amps without tripping the breaker.

 

Certainly none of us here came up with the terminology-- the important thing is that there is a HUGE difference  in available power between  30 and 50 amp RV service.

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  50 amp service = 12000 watts so you have 3 times the power on a 50 

That's what we have said all along.  12000 Watts is 100 amps.  A coach or an RV plug wired for 50 amp service has 100 amp available for use.

30 amp service is 30 amps available  50 amp service is 100 amps available.

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I would guess that if you have a 30 amp coach and you use a 50 to 30 adapter, you would get a true 30 amp versus a 30 amp outlet that has had lots of use and pops the breaker at 25 amps.

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jrock   

Bill 12000 at 120 volts would be 100 but your service is 12000 at 240 volt which is 50 the load will balance over the 240 with the neutral carrying the difference 

 

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wolfe10   

John,

Yes, your math is correct (as is everyone else's):

12,000 watts divided by 120 volts= 100 amps.

The same 12,000 watts divided by 240= 50 amps. 

No argument, no discussion.

The point many of us are trying to make is for those not familiar with electricity is there is a BIG difference in available power between 30 amp and 50 amp.

30 amps times 120 VAC= 3,600 watts. A LOT less than 12,000 watts.

 

I am going to lock this discussion, as everyone is saying the same thing over and over. and over......

Please feel free to PM me if there is something new to add. Thanks.

 

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