50 amp for 30a trailer

[Reverse_snowbird]

If you are worried, you can always put a surge protector or EMS between the adapter and the cord to your tt. Putting an EMS on the line going into the trailer is standard operating procedure with our rig.

[andymil]

The problem would be if you were drawing between 30 amps and 50 amps. This is unlikely (but not impossible). A 30 amp cord will carry a load in excess of 50 amps long enough to trip a 50 amp breaker.

The best way to do it, as others have mentioned, would be the portable 30 amp EMS at the pedestal end of the cord.

A hardwired EMS won’t help in this situation.

[Evereddie]

Originally Posted by andymil

The problem would be if you were drawing between 30 amps and 50 amps. This is unlikely (but not impossible). A 30 amp cord will carry a load in excess of 50 amps long enough to trip a 50 amp breaker.

The best way to do it, as others have mentioned, would be the portable 30 amp EMS at the pedestal end of the cord.

A hardwired EMS won’t help in this situation.

OK, I'll bite. How would an EMS placed on the pedestal end of things help at all in this situation. EMS is not a circuit breaker and would not prevent a 30 amp trailer or cord from drawing 50 amps. (or more) I have looked all through the specs and cannot see how in the world some of you think using one of these is a solution to the problem.At most it TELLS you the amperage draw, no more than that relating to amps.



UNIT SPECS:
• Previous Error Code (PE)
• Normal Operating Conditions (E 0)
• Reverse Polarity Protection (E 1)
• Open Ground Protection (E 2)
• Open Neutral Protection (no power through)
• High Voltage Protection (Line 1-E 3, Line 2-E 5)
• Low Voltage Protection (Line 1-E3, Line 2-E 6)
• High Frequency Protection (E 7)
• Low Frequency Protection (E 8)
• Provides Amperage Usage Reading

[babock]

For people worrying about using a 30A rated extension cord on a 50A breaker, what do you think happens at home when you use a 14 gauge extension cord on a 20A circuit?

The cord is rated at 30A for voltage drop but if there was damage to this 30A cord where there was a dead short, the 50A breaker would indeed trip very quickly.

Originally Posted by andymil

A 30 amp cord will carry a load in excess of 50 amps long enough to trip a 50 amp breaker.

Correct!

[DouglasReid]

Originally Posted by itat

I think we are here.

I agree wholeheartedly.

Let me state that I was never stating it was likely that using the adapter and 30 amp cord would cause problems. It Is NOT likely, but it IS possible.

I was trying to point out that the 50 Amp breaker will not protect the #10 wire used in a 30 Amp service and the 30 Amp breaker in the Power Center WILL NOT trip based on an overload prior to that breaker.

[andymil]

Originally Posted by Evereddie

EMS is not a circuit breaker and would not prevent a 30 amp trailer or cord from drawing 50 amps. (or more)

You are correct. I was wrong. An EMS doesn’t provide over-current protection. Normally that’s already taken care of.

[831 BHDS Flagstaff 2015]

Yakmeat 123 just use the adapter everything will be fine. Just enjoy your camping. Have a great time.....................

[DouglasReid]

Originally Posted by andymil

You are correct. I was wrong. An EMS doesn’t provide over-current protection. Normally that’s already taken care of.

"Normally" assumes the correct size cord plugged in to the correct receptacle which is protected by the correct sized circuit breaker.

[JRW1550]

Bottom line is output current is equal to output load. If you have a 30 amp setup in your camper it will never pull more then 30 amps. It doesn't matter if you are connected to a 50 amp service since you can't pull more then 30 amps. I am not an expert but this is was was taught when I got my electrical engineering degree so I do understand how it works.

[D W]

Originally Posted by DouglasReid

If there is a short in the wiring of your camper or the receptacle on the outside of your camper before the Power Center, the 30 Amp breaker in that Power Center WILL NOT trip.

The 30 amp breaker in your Power Center is only measuring the current going through the breaker, NOT before it gets there.

It is a potential fire, which in a camper can very quickly turn deadly.

A short is a short, no matter if it's a 50A or 30A breaker.

[jtesta1]

Originally Posted by 831 BHDS Flagstaff 2015

I believe if you check the 50 to 30 only feeds one side of the adeptor. One spade is a dummy so it will adept. May be wrong! So if I'm right you are not getting 50 amps to your 30 amp cord.Just what I was told at a camping supply store. I never worrie about it.

The RTO M454 adapter splits the fifty amp just like the 50 amp breaker box does . It runs one into a 30 amp plug the other into a 2o amp plug. It enables me to run two dedicated installed household plugs to run appliances that used to trip my breakers.

[doc73]

Originally Posted by jtesta1

The RTO M454 adapter splits the fifty amp just like the 50 amp breaker box does . It runs one into a 30 amp plug the other into a 2o amp plug. It enables me to run two dedicated installed household plugs to run appliances that used to trip my breakers.

I've seen these, thought about picking one up. I guess this is presuming the 20amp plug is not off the 30amp feed line!

[formerFR]

bottom line is, you are absolutely correct. (per user JRW1550)

The thing we 'fear' about electricity is really our unsurety of how it 'really' works.

Electricity, while available readily at each outlet in your RV, is not 'used' until one of your devices ASKS for it. Otherwise, a device that is not 'ON' is not using any amperage, regardless of what 'amp' your coach is, or what 'amp' size your outlet is.

The issue comes in when you have too many devices asking for electricity at the same time, and they 'heat up' the wiring within you coach, within the shore cord, and within the breaker and wiring to the power source. This heat is the danger, since it can then burn 'thru' the outer coating of your wiring, behind your walls, at your outlets, or at the breaker box itself, and cause a fire.

The Breaker itself is simply an 'in-line' protection so that you don't do 'that'. The breaker is installed to be sized appropriately for the amount of amperage that might ever be asked for, at the same time, through the wiring from the device to the breaker.
If the breaker sense too much 'heat', it TRIPS, disconnecting the power(amperage) from the device.

Everything can now 'cool off'.

So, even if your 30a coach was plugged into a 40amp outlet(one that has a 40amp breaker), your coach is only going to 'allow' it's devices/air conditioners/heaters, etc., to 'ask' for and 'use' up to 30amps, at any given time. Your own coach's 30a main breaker will immediately TRIP if your coach asks for too much, REGARDLESS of what the size of the power source is. 40 amps, 100amps, 1,000,000 amps. No different.

This question, though, sometimes gets 'fuzzy' when you start talking about the good 'ol '50amp RV Service', as it is something a little different than the 'standard' single 30a breaker. It is actually TWO 50amp breakers, mounted in a single 'box', and 'handled' together, so that it trips BOTH breakers immediately together. This is not your 'typical' type of outlet, and it has 4 slots, not just three.
The confusion with '50amp rv service' is that there is a general misunderstanding about 'assuming' that it means an outlet wired to a single 50amp breaker. Not So.
Since it has TWO breakers, it is truly DOUBLE 50amps, for a total of 100amps of usable power for larger coaches that need it, and have the 'split' main panel box to handle it.
Other than the different outlet(4 prong), and the double-pole 50amp breaker, it is simply still 120v incoming power, just more amperages than the typical 30amp rv type - it's 100amps.

Many of us wonder why this is, why not just make it a single 100amp breaker(I wanted to know this too!). Here's why: if you know anything about the sizing of wiring for such a large amount of amperage, you will immediately realize that even just 3 wires of that size in a single Shore Power cord would be extremely heavy and Extremely HARD to manage - and it certainly would NOT roll up into your coach's storage bay.
So, 4 wires sized for 50amp of power rules the camping world - we like to be able to carry, handle, and roll up our 50amp Shore Power cord in our coach!
(also, technically the electrical world calls it 50amp power since it really is a 50amp breaker, just two of them - oh well)

[Dabney]

Many campgrounds, including both private and federal ones, now prohibit the use of 50 amp down to 30 amp adapters because of the fire danger. Most folks are lucky; until they aren’t. Happens enough that campgrounds have learned to be cautious. Going the other way is no problem; a 50 amp rig cannot pull too much power from a 30 amp outlet. But a 30 amp rig can, and sometimes does, create a real fire danger pulling from a 50 amp service.

Be safe...

[Brhehr]

There is nothing wrong with this setup.

A 30 amp cord is made up of 10 AWG copper wire. This wire is capable of handling 60 amps of power (NEC code 250.122) if shorted out to trip the breaker. The cord is protected from over current from the 30 amp main breaker in the trailer.

We see this in everyday life with appliances, lamps and etc. The device is using a 18 to 16 AWG. cord and is plug in to a 15 amp 14 AWG wire or a 20 amp 12 AWG wire receptacle.

Biggest thing with 30 amp cords are that the ends connect together tight. Lose connections cause heat and burn out the ends. This does not mater if you are on a 50 amp circuit or not because the trailer main breaker will not let anymore than 30 amps go through the cord end.

Master Electrician In MN

[fella10]

this thread contains many different(and in some cases completely opposite) FACTS about the subject, ... and most come from the position of being an expert of the subject, ... so I'll throw this into the conversation, because I know this to be a FACT as well, ... one cg we stayed at a couple of years ago, had nothing but 50a power poles and provided a loaner 50a male to 30a female adapter to anyone who did not have one of their own, ... and this was not a rinky dink back yard campground, but a large operation, who if I remember correctly, even provided rv repair service, ... that's when I decided to get one of my own, for just such a need in the future, ...

[andymil]

Brhehr makes a good point. I suppose those of you who would never plug a 30 amp cord into a 50 amp pedestal would never plug a lamp with an 18 awg cord into a receptacle protected by a 20 amp breaker.

[Evereddie]

Originally Posted by andymil

Brhehr makes a good point. I suppose those of you who would never plug a 30 amp cord into a 50 amp pedestal would never plug a lamp with an 18 awg cord into a receptacle protected by a 20 amp breaker.

If there was a 10 watt bulb in the lamp you bet your bippy I would. It's the actual draw not the potential.

[andymil]

Originally Posted by Evereddie

If there was a 10 watt bulb in the lamp you bet your bippy I would. It's the actual draw not the potential.

You’re talking a big risk. The socket could short out.

[rockfordroo]

I think what the naysayers are missing here is that the 50 amp (or 30 amp, or 15 amp) breakers are not really installed to protect from the overload of a single device.

Our rigs typically have a 15 amp breaker feeding a GFCI in the bathroom, with several daisy-chained outlets downstream. So you could have, say, 4 devices plugged into these outlets all pulling 5 amps. So there's 20 amps flowing through the breaker, on wiring designed for 15 amps. So the 15 amp breaker trips to protect the wiring.

Now, you've got five or six of these 15 amp breakers in your power center (maybe a 20 amp or two, too). They are all fed by a 30 amp breaker. The connection between the 30 amp breaker and the five or six 15 amp breakers in the power center is via bus bar; typically able to handle LOTS of current. So why is the 30 amp breaker there? Certainly not to protect the bus bar. It's there because if each of the 15 amp breakers is pulling, say, 10 amps, your total is more than 30 amps and your shore power cable will be theoretically overloaded, so the 30 amp breaker trips. So the 30 amp breaker DOES protect your shore power cord from being overloaded. But it does NOT protect your shore power cord from being shorted.

But as mentioned before, most shorts are dead shorts and 50 amp or 30 amp, the pedestal breaker will trip.

So the only real issue is: how likely do you think it is to have a "not-so-dead" short in your shore power cord that will pull something less than 50 amps? I'd buy a lottery ticket (which is just a tax on people who can't do math) before I take a bet on my shore power cord having this not-so-dead short.

Loose connections typically create heat, but they don't really add load.