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Old 09-26-2017, 02:08 AM   #21
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Originally Posted by Love2camp View Post
The simple answer is no. The cord will burn before the breaker will trip as the cord is only rated for 30amps....
Quote:
Originally Posted by PNTR10
Won't the demand only be for 30 amps? So your 30amp cord should be fine.
Yes: JamJanTan mentioned that his rig is only 30 amp therefore the 30 amp breakers in the rig will trip long before there is enough current to do anything to the 30 amp cord.

Remember that there are two breakers in line before hitting anything in the camper: The ones in the pedestal and then the ones in the panel inside the RV.

Now if there is a short in the cord, or in the internal RV wiring before the wiring goes into the RV's panel then it is possible the cord will act as a big fuse before the 50A breaker trips but that is unlikely.
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Old 09-26-2017, 03:19 AM   #22
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There's no risk to your coach by plugging it into a 50A outlet. It's no different from plugging a 15A hair dryer into a 20A outlet at home. But there IS a risk to your wiring from the power post all the way to your breaker panel. If there is a short or defect in the power cord or any of the connections upstream of the main breaker you risk burning them up and possibly starting a fire in or near your coach. You want a breaker to be the weak link and for must of us that link really should be on the post. That said, if the 30 A outlet were damaged or inoperative when I hooked up I'd likely go ahead and hook up to the 50 A outlet.
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Old 09-30-2017, 02:20 AM   #23
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I don't think it matters which you connect to, but using the 50 amp circuit won't hurt anything.
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Old 12-13-2018, 03:00 AM   #24
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Originally Posted by bruno1950 View Post
I have a 50 amp outlet at my home because my original coach was 50 amp . My current ( no pun intended) coach is 30 amp. I have it plugged in all the time with no problem.
Have your electrician swap out the 50A breaker in the main panel, that feeds that 50A outlet receptacle, for a 30A breaker, and you get the downstream protection.

I personally would not want excessive current available for the system requires to receive, and I am not running a welder with mine either!
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Old 12-13-2018, 03:06 AM   #25
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Originally Posted by Pete'sMH View Post
There's no risk to your coach by plugging it into a 50A outlet. It's no different from plugging a 15A hair dryer into a 20A outlet at home. But there IS a risk to your wiring from the power post all the way to your breaker panel. If there is a short or defect in the power cord or any of the connections upstream of the main breaker you risk burning them up and possibly starting a fire in or near your coach. You want a breaker to be the weak link and for must of us that link really should be on the post. That said, if the 30 A outlet were damaged or inoperative when I hooked up I'd likely go ahead and hook up to the 50 A outlet.
There sure is a lot more of a difference going 30A to 50A, as compared to 15A to 20A!
You have to compare apples to apples.
Besides that, that outlet in the home, the hair dryer has a built in breaker switch!
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Old 12-13-2018, 12:12 PM   #26
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Originally Posted by 10scDust View Post
There sure is a lot more of a difference going 30A to 50A, as compared to 15A to 20A!
You have to compare apples to apples.
Besides that, that outlet in the home, the hair dryer has a built in breaker switch!
That outlet is not a breaker. A GFCI will only trip if there is a short between ground and one of the legs. It may not necessarily trip due to high current--like a breaker.

The idea is that the GFCI will detect issues like if you drop the hair dryer in to a sink full of water (a hot leg will invariably get shorted to ground tripping the GFCI). If you plug two hair dryers into the same GFCI that GFCI won't trip but the 15A breaker its connected to will certainly trip (since a hair dryer by itself will draw around 12A).
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Old 12-13-2018, 01:16 PM   #27
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Originally Posted by 10scDust View Post
Have your electrician swap out the 50A breaker in the main panel, that feeds that 50A outlet receptacle, for a 30A breaker, and you get the downstream protection...
You won't be able to just 'swap out' a 50amp breaker for a 30amp one, since 50amp RV Service is TWO 50amp breakers(double-pole) with a common TRIP handle between them...it is 240v service, not 120v.


and, all this 'discussion' about plugging a 30amp coach into a 50amp RV service outlet, with an appropriate adapter, is overkill, as the adapter provides the single 120v service thru the cord, and the RV's panel's own Main 30amp Breaker is your protection....and it always is, no matter what 'size' the power pedestal breaker is.
You 'can't' use more power than your own Main breaker's size is, regardless, so the 'fear' of plugging into an outlet with a larger breaker is of no concern, and no matter whether you are using your 30amp shore cord, or a 50amp one.

Your own USAGE within your coach will determine if you are 'using' too much amperage for Your RV - your Main breaker will trip, that's what it's there for - and no matter where you are plugged in - even if it's a 30amp pedestal.
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Old 12-13-2018, 07:14 PM   #28
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The breaker on the parks pedestal protects the parks electrical, the main breaker in your RV protects your RV. It really does not matter what amp circuit you plug into, your RV's electrical will protect it.
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Old 12-13-2018, 08:29 PM   #29
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my understanding, if you want to get into the semantics of it, is the following:

in a 3 phase electrical supply, each phase is 120* apart and 120V and since 3 phases = 360* they add up to 0; no neutral, return, or ground required (ground IS needed for safety and protection though obviously) if you mesure each phase to ground it's 120v and across the 2 phases is 240v.

look here for more details in 3 phase:


the standard house gets only 2 of the 3 phases, or poles. normally a device uses one or the other pole, neutral and ground again for safety. more power hungry devices, like air conditioners, use both poles.

so each pole has a breaker for 50A on a 50A circuit. theoretically you have 100A to play with. however both of these breakers are physically tied together. since the design is assuming both poles will be loaded equally, if theres a overload both breakers will pop together.

it's actually unsafe to use a 50A to 30A adapter. say theres a short before the the 30A breaker in the coach or it fails. since the 50A breakers are physically linked, it will take more current then 50A to trip one breaker and move the other. before the compromised 50A breaker can trip the cord melts or catches fire. it's much safer to use a 30A breaker on a 30A cord.
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Old 12-13-2018, 09:01 PM   #30
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Originally Posted by Diemaster View Post
my understanding, if you want to get into the semantics of it, is the following:

in a 3 phase electrical supply, each phase is 120* apart and 120V and since 3 phases = 360* they add up to 0; no neutral, return, or ground required (ground IS needed for safety and protection though obviously) if you mesure each phase to ground it's 120v and across the 2 phases is 240v.

look here for more details in 3 phase:


the standard house gets only 2 of the 3 phases, or poles. normally a device uses one or the other pole, neutral and ground again for safety. more power hungry devices, like air conditioners, use both poles.

so each pole has a breaker for 50A on a 50A circuit. theoretically you have 100A to play with. however both of these breakers are physically tied together. since the design is assuming both poles will be loaded equally, if theres a overload both breakers will pop together.

it's actually unsafe to use a 50A to 30A adapter. say theres a short before the the 30A breaker in the coach or it fails. since the 50A breakers are physically linked, it will take more current then 50A to trip one breaker and move the other. before the compromised 50A breaker can trip the cord melts or catches fire. it's much safer to use a 30A breaker on a 30A cord.
Actually the two 50A breakers are mechanically connected at the "tab" sticking out of the panel. Thus when one trips it forces the other to trip. I don't see how you need "more current than 50A" to force a 50A breaker to trip (they are spring loaded and thermally tripped--using a bi-metallic strip: when the breaker gets hot enough it releases and the spring forces the "tab" to move breaking the connection--it isn't the current that moves the "tab" its a spring). Some breakers also have a magnetic tripping mechanism that will trip instantly on a short.

Which does mean, that if you don't have a good solid wire connection to the breaker it will actually trip with less current than what is on the breaker (as the bad connection will tend to heat up)--I had this happen once where a screw wasn't tight on a breaker for a dryer. It kept tripping the breaker.
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Old 12-13-2018, 10:35 PM   #31
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remember, though, we're discussing a 30amp coach plugging into a 50amp double-pole RV outlet, via an adapter.
Since a 30amp coach's Main panel is designed for a maximum of 30amps of usage by the RV, it's highly unlikely that all the individual breakers in the panel, even if all used at the same time, would result in anything more than 30amps in the first place.
And, even if the owner tried to use too much, the INDIVIDUAL breakers are in place to also manage each circuit, EVEN if the main breaker had some type of issue.

I think the conversation is overrated about this possibility, and it's unlikely anyone employing this adaptation from 50amp to 30amp is going to run into any likely problems, especially since they already KNOW they are plugging into a different type of outlet than the 'norm'.

Go camping..... and worry less... RV cords and adapters are designed for these types of situations.
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Old 12-13-2018, 10:46 PM   #32
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The breaker on the parks pedestal protects the parks electrical, the main breaker in your RV protects your RV. It really does not matter what amp circuit you plug into, your RV's electrical will protect it.
All circuit breakers work only down stream. If the high line coming into your pedestal shorts, it will not trip the circuit breakers in your coach's pedestal or in your coach for that matter. Any circuit breaker only monitors the current (not the voltage) flowing through it. When the current exceeds the rated amount the CB will trip. Well it not that simple. 30 amp circuit breakers with trip if they pass 28 amps for 10 minutes. The more they are tripped the less current it takes to trip. This is because they use a magnetic latch. Over time tripping then manually or automatically reduces the magnetism of the latch. By the way all the new house construction requires CAFCI and all new RV construction should have them.
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