50amp to 30amp=?

[alank]

Don't think you can plug a residential hair dryer in to that. I know you can buy the parts, and it's physically possible to go from a 50A breaker to a 15A receptacle. The electrical code doesn't allow this for some very well established safety reasons.

[twinboat]

Originally Posted by alank

Don't think you can plug a residential hair dryer in to that. I know you can buy the parts, and it's physically possible to go from a 50A breaker to a 15A receptacle. The electrical code doesn't allow this for some very well established safety reasons.

I believe that device has a circuit breaker in its body. Probably a 20 amp, making it safe.

[Mudfrog]

Originally Posted by alank

Don't think you can plug a residential hair dryer in to that. I know you can buy the parts, and it's physically possible to go from a 50A breaker to a 15A receptacle. The electrical code doesn't allow this for some very well established safety reasons.

Oh shoot,, I did not even look at the plug configuration when I posted the image. That one would not work at all by itself since it's made to deliver 240 volts.

The one below with a built in 20 amp breaker would do the trick though.



I agree with you that it would not be safe just using a 50/15 amp dogbone by itself.

[alank]

Originally Posted by twinboat

I believe that device has a circuit breaker in its body. Probably a 20 amp, making it safe.

I looked at that again, didn't notice the tip of the little red button before. I think you're right about the circuit breaker.

[Piros1]

Interesting how many types of adaptor plug/receptacle combinations there are. Reminds me of what we use to call a water thief designed to go over the water faucets at public campgrounds that did not have a hose bib, they were used to connect a hose to and fill your water tank. The hood old days when there wasn’t Covid to worry about.

[Fugitive861]

So, if the OP's 30 amp rv is plugged into a 50 amp campground pedestal, everything downstream of the RV's 30 amp main breaker in the RV breaker panel will be protected at 30 amps. Everything before, or upstream of the 30 amp main (i.e. ATS, shorepower cord) will be protected on the 50 amp campground breaker. Theoretically if there was a problem with the 10 gauge (30amp rated) shorepower cord the cord could melt or burn as the 50 amp circuit breaker may not trip.

[richard5933]

Assuming the following:

You have a 30-amp RV,

You're using a 30-amp shore power cord,
That 30-amp power cord is plugged into a 50-amp pedestal via a dogbone adapter,

Then,

Your shore power cord and dogbone adapter are not properly protected. The purpose of a circuit breaker is to protect the wiring downstream from it. The 50-amp breaker is designed to protect wiring intended to withstand 50 amps on each leg. Your shore power cord is designed to withstand 30 amps. Therefore, it's not properly protected.

Now, before anyone flames me with the unlikelihood of any problems actually occurring, I get it. But it is possible.

Here's how...

The breaker panel in a 30-amp RV has a number of circuits, and all the circuits will be fed from a common single hot lead. The total of all the circuits being served will add up to more than 30 amps.

Not every RV has a master breaker which limits the draw on the panel to 30 amps, as they count on the breaker at the pedestal to do the protecting. Some do.

If you don't have a main 30-amp breaker in your panel, or if something in the cord itself fails, there is a chance that you'll be pulling more than 30 amps through that shore power cord and dogbone.

[Old-Biscuit]

Originally Posted by richard5933

Assuming the following:

You have a 30-amp RV,

You're using a 30-amp shore power cord,
That 30-amp power cord is plugged into a 50-amp pedestal via a dogbone adapter,

Then,

Your shore power cord and dogbone adapter are not properly protected. The purpose of a circuit breaker is to protect the wiring downstream from it. The 50-amp breaker is designed to protect wiring intended to withstand 50 amps on each leg. Your shore power cord is designed to withstand 30 amps. Therefore, it's not properly protected.

Now, before anyone flames me with the unlikelihood of any problems actually occurring, I get it. But it is possible.

Here's how...

The breaker panel in a 30-amp RV has a number of circuits, and all the circuits will be fed from a common single hot lead. The total of all the circuits being served will add up to more than 30 amps.

Not every RV has a master breaker which limits the draw on the panel to 30 amps, as they count on the breaker at the pedestal to do the protecting. Some do.

If you don't have a main 30-amp breaker in your panel, or if something in the cord itself fails, there is a chance that you'll be pulling more than 30 amps through that shore power cord and dogbone.

Hummmm...interesting

Never have seen or heard of a Main AC Panel W/O Main CB(s)

[richard5933]

Originally Posted by Old-Biscuit

Hummmm...interesting

Never have seen or heard of a Main AC Panel W/O Main CB(s)

There are lots of older RVs out there without a main breaker, as well as many DIY units. Take a look online and you'll see no shortage of home-built travel trailers and van conversions, not to mention all the people that are renovating older units and putting them back on the road.

Even if the RV itself has a 30-amp main breaker, that still leaves the shore power cord and dogbone unprotected. Again, the breakers are designed to protect things downstream from them, not upstream. Yes, the odds are that a shore power cord isn't going to fail on its own, but a cord rated for 30 amps should not be plugged into a 50-amp circuit, as it's unprotected.

Not everything out there is fully compliant with the latest codes and recommendations. Our coach was a top-of-the-line professional conversion done in 1974 on a brand-new shell. It uses what was at the time a state-of-the art 120v load center designed for marine and RV use. There is no main breaker at all and no place to easily add one. We're not alone in this regard.

I get it that most people will never have a problem plugging a 30-amp RV into a 50-amp receptacle, but I hate to see blanket statements made about safety issues that have such glaring exceptions.

And unfortunately, the people that are unaware they are lacking a main breaker might very well be the people that plug into that 50-amp receptacle. You'd be surprised at the number of people who think simply plugging into the 50-amp receptacle will provide a 30-amp RV with more power than the 30-amp one, never realizing their wiring is not designed to handle pulling the extra load.

[Johnynorthla]

Originally Posted by richard5933

There are lots of older RVs out there without a main breaker, as well as many DIY units. Take a look online and you'll see no shortage of home-built travel trailers and van conversions, not to mention all the people that are renovating older units and putting them back on the road.

Even if the RV itself has a 30-amp main breaker, that still leaves the shore power cord and dogbone unprotected. Again, the breakers are designed to protect things downstream from them, not upstream. Yes, the odds are that a shore power cord isn't going to fail on its own, but a cord rated for 30 amps should not be plugged into a 50-amp circuit, as it's unprotected.

Not everything out there is fully compliant with the latest codes and recommendations. Our coach was a top-of-the-line professional conversion done in 1974 on a brand-new shell. It uses what was at the time a state-of-the art 120v load center designed for marine and RV use. There is no main breaker at all and no place to easily add one. We're not alone in this regard.

I get it that most people will never have a problem plugging a 30-amp RV into a 50-amp receptacle, but I hate to see blanket statements made about safety issues that have such glaring exceptions.

And unfortunately, the people that are unaware they are lacking a main breaker might very well be the people that plug into that 50-amp receptacle. You'd be surprised at the number of people who think simply plugging into the 50-amp receptacle will provide a 30-amp RV with more power than the 30-amp one, never realizing their wiring is not designed to handle pulling the extra load.

I’m the OP. This is exactly the reason I started this post. It doesn’t make sense to me if I’m using a regular 30 amp cord, and a 50/30 dog bone adapter, that it’s ok. All the downstream wires and electronics, including the transfer switch, from the panel down are not rated for 50 amps, unless I were to use that special type of 50/30 dog-bone adapter that would interrupt the circuit before the 30 amp cord. And for those that state for a fire to occur from an overhead circuit would take X,Y,Z to happen, that is the ingredients for Murphy’s law to kick in!

See NEC code on 10ga;

A 10 gauge wire can handle 50 amps bare copper like a power line but most insulated wire is rated by NEC at 35 amps max with a 30 amp circuit the normal use for 10 gauge. ... 50 Amps is a large current and it will make 10 guage wire to heat up.

So if the statement above is true, all those dog bone adapters being sold are misrepresented!

[Old-Biscuit]

Originally Posted by richard5933

There are lots of older RVs out there without a main breaker, as well as many DIY units. Take a look online and you'll see no shortage of home-built travel trailers and van conversions, not to mention all the people that are renovating older units and putting them back on the road.

Even if the RV itself has a 30-amp main breaker, that still leaves the shore power cord and dogbone unprotected. Again, the breakers are designed to protect things downstream from them, not upstream. Yes, the odds are that a shore power cord isn't going to fail on its own, but a cord rated for 30 amps should not be plugged into a 50-amp circuit, as it's unprotected.

Not everything out there is fully compliant with the latest codes and recommendations. Our coach was a top-of-the-line professional conversion done in 1974 on a brand-new shell. It uses what was at the time a state-of-the art 120v load center designed for marine and RV use. There is no main breaker at all and no place to easily add one. We're not alone in this regard.

I get it that most people will never have a problem plugging a 30-amp RV into a 50-amp receptacle, but I hate to see blanket statements made about safety issues that have such glaring exceptions.

And unfortunately, the people that are unaware they are lacking a main breaker might very well be the people that plug into that 50-amp receptacle. You'd be surprised at the number of people who think simply plugging into the 50-amp receptacle will provide a 30-amp RV with more power than the 30-amp one, never realizing their wiring is not designed to handle pulling the extra load.

1974 Custom Coach and/or Home Made/converted DYIs ???

OP has a 2019 Jayco

[richard5933]

Originally Posted by Old-Biscuit

1974 Custom Coach and/or Home Made/converted DYIs ???

OP has a 2019 Jayco

Understood. My premise is still valid.

The dog bone adapter and the shore power cord are left unprotected. Doesn't matter which RV you're discussing, if a cordset and adapter rated for 30 amps are plugged into an outlet protected by a 50-amp breaker it's not protected. As I've already agreed it's unlikely that there will be a problem. Obviously there are times when using an adapter to plug a 30-amp rig into a 50-amp outlet will be necessary, but it's just not something that should be done on a regular basis when a proper 30-amp outlet is available, IMO.

Specifically to your point...Not everyone who will stumble upon this thread will own a 2019 Jayco. Not everyone will have an RV which is protected by a main breaker. My 1974 Custom Coach and DIY rigs are just two examples of RVs without one, but surely there are others. In these situations, it's way too easy to overload a 30-amp cordset and dog bone adapter and create a hazardous situation.