30Amp, 50Amp ???

[stevebell]

Originally Posted by widgetwizard

I wish the OP would get back to us - I assumed his actual, normal, cord was a 15A cord - not an extension lead, and that he had a 15A breaker internally.

Yes I have the breaker in the scamp. I use large gauge cord to plug into electric.


thanks for all the helpful insight and links.

[Conrad S.]

If the Scamp came with a 15-amp cord, it must not have any equipment that would draw more current than that. The mere availability of 30 amps does not mean that the trailer will draw that much.

[Lloyd (aka Santa) Coltman]

The 15 amp breaker in the 'Scamp' will protect all within the RV, from the point of connection into said breaker and 'Downstream'.
Assuming your RV cord to be no more than 12 ga (possibly only 14 ga), you're connecting via an adapter to a 30 Amp (breaker protected) outlet , the adapter and cord become the weak link (NOT PROTECTED).
If, in fact, your cord is 12 ga, and the adapter is built using 14 ga internal connections, the adapter is the most likely to fail, protecting the cord.
On the other hand, if your cord is 14 ga, it's a 'Saw-off' which will fail first, and the failure COULD OCCUR at the breaker input (inside the RV).
I believe most of the adapters of that type are flagged 'Max 15 Amp'. That doesn't mean they will protect the circuit by disconnecting power.
Just because it's a '30 Amp site', does not exclude also having a 15 Amp protected outlet. If it does, stay away from the adapters, and connect directly.
Note: I have 3 adapters that allow me to connect my RV-30 cord to a 15 Amp outlet (reverse of what you're looking at) and all are tagged 'Max 15A', meaning 'DON'T EXCEED 15 Amp', nothing more.

[Rzrbrn]

One other issue: Someone mentioned that the unit would be plugged in throughout the winter and would therefore keep the battery charged. Just a word of caution; most of the older converters are 2 stage, so keeping the battery plugged in will overcharge the battery. This happened to me in my Casita. So I installed a 3 stage converter just so I can now keep the battery charging all the time. Pulling the battery out of the Casita to put a trickle charger on it is a real pain in the rear. Now I don't worry about it.

[Lloyd (aka Santa) Coltman]

The really old 'Converters' were controlled only by the restricted charging output, guaranteed to boil your battery, and/or burn out bulbs, because as current went down voltage went up. I've seen load side voltage as high as 18 Volts, with only 1 bulb load. Then, POOF!
Mind you, 'Load' side was connected to its own supply, and charge was a separate small supply (when on shore power). Load was only connected to battery (Via relay - more troubles) when there was no shore power.
Thank goodness, we've progressed.

[Rzrbrn]

My 2013 Casita had a 2 stage Progressive Dynamics converter. It boiled 2 batteries before I investigated and installed a new Progressive Dynamics PD4645V. The first 4645 died after 4 months so I installed a second one under warranty. All is well now, but my point is that 2013 is not that old of a trailer and it had the 2 stage converter.

[M. Bober]

Originally Posted by Darral T.

Ok...I'm going to TOTALLY disagree based on ONE thing. What amperage is the cord rated for that's being used to plug into the 30A circuit?

IF it AND/OR the circuitry is not rated for 30A and you pull over 20A or what ever the rating is, you stand the BIG chance for a fire hazard!! Why? Because if you have an overload, the 30A most likely will NOT trip. Just something to think about. Make sure you do NOT over load that cord and that when it gets inside your Scamp, you have the sufficient 15-20A breakers to protect the interior plugs!!

What I'm telling you may not be a popular answer, but I PROMISE you it's sound advice!! I dont want to see anyone hurt.

ABSOLUTELY TRUE! If you are connected to a 30 amp circuit, the breaker will NOT trip when your 15 amp rated appliance is glowing red hot and getting ready to burst into flames. Your onboard circuit breakers will protect downstream but devices between the service connect and the breakers are at risk. I see this frequently at boat yards and marinas where 15 amp receptacles are in short supply and adapters are used to connect to 30/50 services. Power tools--and worse, space heaters--that need to be protected at 15 amps will not trip a 30 amp breaker.


Your puny extension cord is not rated for the amps you are considering.



Be smart. Be safe.

[C&G in FL]

Home outlet circuits are typically on 20a circuits (20a breakers and #12 wire). 16 gauge wire is not rated for 20a but many appliances (lamps, televisions are plugged into 20a circuits. The breaker is intended to trip if the total draw exceeds 20a so that the circuitry wiring doesn’t overheat and melt.
If any trailer has a main breaker, you can plug an extension in as long as it is rated for the amperage of the main breaker (#14 for 15a, #12 for 20@ and #10 for 30@). That means you can plug into a 30a or 50a receptacle with an adapter and a cord rated for the trailer’s main breaker (if not defective) because if draw exceeds what the main breaker it will trip shutting down all flow, thereby protecting the trailer’s wiring as well as the extension cord feeding the trailer. No current means no heat buildup and no fire hazard.

[steve dunham]

Evidently the NEC and the EE’s . master electricians and safety people , who write the electrical code are all wrong and don’t know what they are talking about
I know several people who are on NEC code panels maybe they should read this forum .
My thanks to Jon V

[Lloyd (aka Santa) Coltman]

Originally Posted by M. Bober

ABSOLUTELY TRUE! If you are connected to a 30 amp circuit, the breaker will NOT trip when your 15 amp rated appliance is glowing red hot and getting ready to burst into flames. Your onboard circuit breakers will protect downstream but devices between the service connect and the breakers are at risk. I see this frequently at boat yards and marinas where 15 amp receptacles are in short supply and adapters are used to connect to 30/50 services. Power tools--and worse, space heaters--that need to be protected at 15 amps will not trip a 30 amp breaker.


Your puny extension cord is not rated for the amps you are considering.



Be smart. Be safe.

Exactly my point in response #23 ! The 15 (or 20) Amp cord and the adapter WILL NOT BE PROTECTED FROM FAILURE (FIRE) by the 30 Amp supply breaker. Talk to the property Owner/Manager and determine if an outlet matching your cord's capacity is available at the site. You do not have a need, or capacity for 30 Amps! Avoid connecting anything that can't handle what the the supply is capable of.
Unless there's some other reason for taking the 30 Amp site, assuming a matching outlet for your cord is available, why bother?
At home, I connect to a 30 Amp outlet, fed by #12 wire and a 20 Amp breaker. Perfectly legal, because the supply breaker is sized to protect the LOWEST CAPACITY circuit component (the supply wire).
I only use adapters to connect to supplies that can't produce more than the capacity of the adapter (15 Amp Max.)

[steve dunham]

Originally Posted by Lloyd (aka Santa) Coltman

Exactly my point in response #23 ! The 15 (or 20) Amp cord and the adapter WILL NOT BE PROTECTED FROM FAILURE (FIRE) by the 30 Amp supply breaker. Talk to the property Owner/Manager and determine if an outlet matching your cord's capacity is available at the site. You do not have a need, or capacity for 30 Amps! Avoid connecting anything that can't handle what the the supply is capable of.
Unless there's some other reason for taking the 30 Amp site (and matching service to your cord is available) why bother?
At home, I connect to a 30 Amp outlet, fed by #12 wire and a 20 Amp breaker. Perfectly legal, because the supply breaker is sized to protect the LOWEST CAPACITY circuit component (the supply wire).
I only use adapters to connect to supplies that can't produce more than the capacity of the adapter (15 Amp Max.)

Technically speaking (NEC ) a 30 amp receptacle requires a 30 amp circuit
The NEC does allow 15 or 20 amp receptacles on a 20 amp circuit but that is an excepion to the code
Short circuit protection is different than over current protection
A #10 wire if shorted will cause a 50 amp breaker to trip and the wire
will withstand the fault current . I have shorted out a 30 amp circuit
(#10 wire) and the short took out a 200 amp time delay fuse

I once replaced the fuse link in a REN fuse with a piece of #12 solid CU wire
The #12 wire carried a load in excess of 160 amps before the conductor melted .

In Art 430 of the NEC it states that under certain conditions the overcurrent protection for a conductor can be set at 1400% of the conductors ampacity
When you overload a conductor continually the insulation fails long before the conductor fails . That’s why a #10 wire has different ampacities based on the type of insulation used , ambient temperature , whether in free air or in a conduit , number of conductors in a cable / raceway , length of run ,etc etc
There is nothing illegal or unsafe with plugging your 30 amp trailer cord into a 50 amp circuit using an adaptor
Again read the section of the NEC covering the 10 ft and 25 ft tap rules

My knowledge comes from being a master electrician and a certified electrical instructor for over 40 years and not from reading a paragraph on Wikepedia

[Lloyd (aka Santa) Coltman]

Originally Posted by steve dunham

Technically speaking (NEC ) a 30 amp receptacle requires a 30 amp circuit
The NEC does allow 15 or 20 amp receptacles on a 20 amp circuit but that is an excepion to the code
Short circuit protection is different than over current protection
A #10 wire if shorted will cause a 50 amp breaker to trip and the wire
will withstand the fault current . I have shorted out a 30 amp circuit
(#10 wire) and the short took out a 200 amp time delay fuse

I once replaced the fuse link in a REN fuse with a piece of #12 solid CU wire
The #12 wire carried a load in excess of 160 amps before the conductor melted .

In Art 430 of the NEC it states that under certain conditions the overcurrent protection for a conductor can be set at 1400% of the conductors ampacity
When you overload a conductor continually the insulation fails long before the conductor fails . That’s why a #10 wire has different ampacities based on the type of insulation used , ambient temperature , whether in free air or in a conduit , number of conductors in a cable / raceway , length of run ,etc etc
There is nothing illegal or unsafe with plugging your 30 amp trailer cord into a 50 amp circuit using an adaptor
Again read the section of the NEC covering the 10 ft and 25 ft tap rules

My knowledge comes from being a master electrician and a certified electrical instructor for over 40 years and not from reading a paragraph on Wikepedia

You may be quite correct under US Code, but in my case, the use of the RV-30 receptacle is strictly for convenience (Fed by 20 Amp Breaker, GFCI, and no adapter required). Passed by Inspector, with no problems, but he commented on the job: Over-sized feed conductors in over-sized entrance conduit, reduced size neutral, vertical/horizontal wire runs with radiused bends, not diagonal P-P. etc." I haven't seen work like that in years".
I'm not an electrician, but a perfectionist 'Technician'.

[M. Bober]

Originally Posted by CPW

Home outlet circuits are typically on 20a circuits (20a breakers and #12 wire). 16 gauge wire is not rated for 20a but many appliances (lamps, televisions are plugged into 20a circuits. The breaker is intended to trip if the total draw exceeds 20a so that the circuitry wiring doesn’t overheat and melt.
If any trailer has a main breaker, you can plug an extension in as long as it is rated for the amperage of the main breaker (#14 for 15a, #12 for 20@ and #10 for 30@). That means you can plug into a 30a or 50a receptacle with an adapter and a cord rated for the trailer’s main breaker (if not defective) because if draw exceeds what the main breaker it will trip shutting down all flow, thereby protecting the trailer’s wiring as well as the extension cord feeding the trailer. No current means no heat buildup and no fire hazard.

Is that smoke I smell?

[Lloyd (aka Santa) Coltman]

Could be, if you're using a cord rated for 15 Amp or 20 Amp plugged into a 30 amp plug-in, via an adapter, because the supply breaker (at post) will pass 150%-200% of the rated capacity of of the cord. If you happen to be plugged into a 50 Amp plug-in, using 2 adapters 50A - 30A and 30A-15A Guess what, you'll have a circuit capable of pounding 50 Amps into a cord rated for 15-20 Amps (Even though you're only using 1 leg of 2 leg circuit) because it is fed by one pole of a 2-pole 50 Amp breaker.
Yes, the 50 amp plug-in is 120/240 Volt, but is seldom used as 240 Volt in RVs. Most usual is as 2- 125 Volt connections.

[C&G in FL]

Originally Posted by Lloyd (aka Santa) Coltman

Could be, if you're using a cord rated for 15 Amp or 20 Amp plugged into a 30 amp plug-in, via an adapter, because the supply breaker (at post) will pass 150%-200% of the rated capacity of of the cord. If you happen to be plugged into a 50 Amp plug-in, using 2 adapters 50A - 30A and 30A-15A Guess what, you'll have a circuit capable of pounding 50 Amps into a cord rated for 15-20 Amps (Even though you're only using 1 leg of 2 leg circuit) because it is fed by one pole of a 2-pole 50 Amp breaker.
Yes, the 50 amp plug-in is 120/240 Volt, but is seldom used as 240 Volt in RVs. Most usual is as 2- 125 Volt connections.

The supply breaker may be capable of passing 150-200% of what the cord is rated but if there is a downstream breaker rated lower than the supply breaker, it will trip if its capacity is exceeded. The typical new house has a 200 amp main breaker. It feeds circuits that have 20, 30, and 50 amp breakers. You cannot get 200 amps out of an outlet that is protected by a 30 amp breaker, even though it is attached to a 200 amp bus. The 30 amp breaker will trip if more than 30 amps are drawn for a short period of time. That is why you cannot run a coffee maker, the microwave, and a hair dryer at the same time in one of these small trailers. The load would exceed 30 amps and the main breaker would trip, even if none of the sub-circuits were overloaded. This would prevent the trailer’s shore power cord (10 gauge if 30 amps) from melting and starting a fire. If plugging in a shore power cord rated for 20 amps attached to a trailer with a 20 amp main breaker using an adapter in a 30 or 50 amp outlet created a fire hazard, then plugging in a lamp with 16 gauge zip cord into an outlet on a 20 amp circuit would do the same. Real estate agents would be unemployed because there would be no houses to sell, they would all be burned to the ground.

[Lloyd (aka Santa) Coltman]

No, I'm not being a comedian. I don't want someone hurt or losing their RV.
I do understand electricity, after Many years of working with it.
The OP stated his power cord would plug into any standard Household outlet (15 Amp- 12 Ga.at best).
The problem is: The main breaker in the RV WILL NOT Protect the circuit between the supply and said main breaker, if there is a fault or overload prior to the Main breaker. The RV main will ONLY trip if the fault or overload is 'downstream' of it. Also, there is a supply clearly capable of anywhere from 150% to 333% of the RV cord's rating (depending on whether it is a 30 amp supply connected to a 12 Ga. cord or a 50 Amp supply connected to a 14 Ga. cord).
The 'Supply' breaker will only trip if the fault draws enough current (30+ to 50+ Amps). This leads to the possibility of an electrical fire within the trailer. The saving grace might be the 30A to 15A adapter, which will likely have 14 Ga. internals and possibly fail first.

[C&G in FL]

Originally Posted by Lloyd (aka Santa) Coltman

No, I'm not being a comedian. I don't want someone hurt or losing their RV.
I do understand electricity, after Many years of working with it.
The OP stated his power cord would plug into any standard Household outlet (15 Amp- 12 Ga.at best).
The problem is: The main breaker in the RV WILL NOT Protect the circuit between the supply and said main breaker, if there is a fault or overload prior to the Main breaker. The RV main will ONLY trip if the fault or overload is 'downstream' of it. Also, there is a supply clearly capable of anywhere from 150% to 333% of the RV cord's rating (depending on whether it is a 30 amp supply connected to a 12 Ga. cord or a 50 Amp supply connected to a 14 Ga. cord).
The 'Supply' breaker will only trip if the fault draws enough current (30+ to 50+ Amps). This leads to the possibility of an electrical fire within the trailer. The saving grace might be the 30A to 15A adapter, which will likely have 14 Ga. internals and possibly fail first.

So you are in effect suggesting that a 14 gauge extension cord (rated for 15 amps) plugged into a 30 amp RV outlet using a 30 to 15 amp adapter in order to power an electric drill or a blender constitutes a major safety hazard, whereby the drill or blender could be damaged, burst into flames, or the 14 gauge cord could melt and start a fire from the amount of current used by these appliances. I ask this because this is what you seemingly are implying. If that is true, then I guess I should be very concerned that my table lamps in my home with 18 gauge cords are plugged into 20 amp outlets which could flood the 18 gauge cord with 200% or more of their capacity.
Thank you for being concerned about my property and my safety. I will, however, use my 50 to 30 amp adapter (which only utilizes one leg of the 240 volt 50 amp outlet, providing 120 volts) to connect my trailer to the grid if a 50 amp source is all that is available, because my trailer cannot and will not draw more than 30 amps through its shore power cord because of the downstream breaker regardless of what amperage the supply is. And you are correct that a downstream breaker will not protect anything upstream. However, a wire will not heat to fire starting levels if no current is flowing or if whatever current is flowing does not exceed the wire’s rating. I fail to see how a 30 amp rated cord’s capacity can be exceeded when the downstream breaker restricts flow into the trailer to 30 amps maximum. Any fault or overload in the trailer should, unless the trailers main breaker is defective, trip it. But if the trailer’s main breaker is defective, it wouldn’t matter if the trailer were connected to a 30 or 50 amp source because if you add up the amps the sub-circuits are capable of carrying, the sum will be higher than the main breaker’s rating. And if a breaker inside the trailer were to fail, you could overload a sub-circuit to a dangerous level. In reality, ANY use of electricity poses a risk which should be evaluated. But for safety reasons, I promise I won’t stand in a puddle when doing so. I guess we will have to agree to disagree on the use of larger to smaller amperage adapters.

[steve dunham]

Originally Posted by CPW

So you are in effect suggesting that a 14 gauge extension cord (rated for 15 amps) plugged into a 30 amp RV outlet using a 30 to 15 amp adapter in order to power an electric drill or a blender constitutes a major safety hazard, whereby the drill or blender could be damaged, burst into flames, or the 14 gauge cord could melt and start a fire from the amount of current used by these appliances. I ask this because this is what you seemingly are implying. If that is true, then I guess I should be very concerned that my table lamps in my home with 18 gauge cords are plugged into 20 amp outlets which could flood the 18 gauge cord with 200% or more of their capacity.
Thank you for being concerned about my property and my safety. I will, however, use my 50 to 30 amp adapter (which only utilizes one leg of the 240 volt 50 amp outlet, providing 120 volts) to connect my trailer to the grid if a 50 amp source is all that is available, because my trailer cannot and will not draw more than 30 amps through its shore power cord because of the downstream breaker regardless of what amperage the supply is. And you are correct that a downstream breaker will not protect anything upstream. However, a wire will not heat to fire starting levels if no current is flowing or if whatever current is flowing does not exceed the wire’s rating. I fail to see how a 30 amp rated cord’s capacity can be exceeded when the downstream breaker restricts flow into the trailer to 30 amps maximum. Any fault or overload in the trailer should, unless the trailers main breaker is defective, trip it. But if the trailer’s main breaker is defective, it wouldn’t matter if the trailer were connected to a 30 or 50 amp source because if you add up the amps the sub-circuits are capable of carrying, the sum will be higher than the main breaker’s rating. And if a breaker inside the trailer were to fail, you could overload a sub-circuit to a dangerous level. In reality, ANY use of electricity poses a risk which should be evaluated. But for safety reasons, I promise I won’t stand in a puddle when doing so. I guess we will have to agree to disagree on the use of larger to smaller amperage adapters.

CPW , I understand your frustration with trying to explain something when people refuse to listen to the explanation .
They don’t understand overcurrent protection , fault currents , trip curves , short circuit ratings etc , etc and this forum does not have enough space to explain it all
It’s up to you if you wish to keep beating your head against the wall , I am done

The only thing to do is to replace your 30 amp service cord with a 50 amp cord
and then you can plug it into anything ???

[Lloyd (aka Santa) Coltman]

The danger has nothing to do with what the appliances/tools would NORMALLY draw. It has to do with a concealed potential fault, whereby a circuit can supply far in excess of the rated capacity of a concealed connection.
Should a fault occur in an appliance/tool that is openly plugged into a higher capacity circuit, it is easy to unplug and disconnect it.
But when the fault occurs at a 'Hardwired, concealed connection' ie: inside the RV power panel, up to the input to the RV main breaker, it is conceivable that the fault could occur at night, when occupants are sleeping and could be overcome by toxic smoke, thus unable to perform a disconnect.
That is the reason concealed wiring is protected by appropriate sized breakers/fuses. (30 to 50 Amps is NOT appropriate for 12 Ga - 14 Ga.)
Hopefully, the adapter would become the limiting factor, and disconnect the power, because the 'Supply breaker' won't.

[Jon Vermilye]

Originally Posted by Lloyd (aka Santa) Coltman

No, I'm not being a comedian. I don't want someone hurt or losing their RV.
I do understand electricity, after Many years of working with it.
The OP stated his power cord would plug into any standard Household outlet (15 Amp- 12 Ga.at best).
The problem is: The main breaker in the RV WILL NOT Protect the circuit between the supply and said main breaker, if there is a fault or overload prior to the Main breaker. The RV main will ONLY trip if the fault or overload is 'downstream' of it. Also, there is a supply clearly capable of anywhere from 150% to 333% of the RV cord's rating (depending on whether it is a 30 amp supply connected to a 12 Ga. cord or a 50 Amp supply connected to a 14 Ga. cord).
The 'Supply' breaker will only trip if the fault draws enough current (30+ to 50+ Amps). This leads to the possibility of an electrical fire within the trailer. The saving grace might be the 30A to 15A adapter, which will likely have 14 Ga. internals and possibly fail first.

Although I doubt I'll change anyone's mind, a couple of points.

1. When choosing a cord to go between the power source (pedestal) and the trailer, the size should be determined by the trailer's main breaker. A smaller sized cord, particularly if it is over length, may cause enough voltage drop to damage air conditioners.

2. While I understand the concern some have about plugging a #12 cord (the proper size for the trailer in question) into a 30 amp source, the reason it is not a problem is the trailer main (a 20 amp breaker in this case) will protect the cord from an overload IN THE TRAILER'S distribution system; if too many appliances are connected causing more than 20 amps load, the main will trip.

As to the wiring between the pedestal & the trailer main breaker, the only conceivable overload would be a short since there are no loads before the main.

The 30 amp breaker is likely a thermal/magnetic breaker (the only other type that would be acceptable to the NEC would be a magnetic breaker, which is unlikely since they are more expensive). The magnetic portion of the thermal/magnetic breaker trips very quickly on major overloads. A dead short (again, the only fault that its likely before the trailer's main breaker) is going to trip a 30 or 50 amp breaker even through a 50' #12 extension cord.