Wow! Unplugged 50 to 30 amp adapter....50amp female melted

[jeeperdude10]

Stayed 2 weeks in Floirda. With the 30amp plug with just AC and one other appliance (fan) kept tripping breaker. Put my 50 amp to 30 amp adapter and when left after 1 week of redoing....found my 'female' 30amp melted on the "dog bone". Any ideas as to why? Never did trip breaker after using adapter.

[myredracer]

If something ever happened to a shore power cord itself, it'd be a dead short because it got damaged, in which case a 30 or 50 amp breaker supplying it would trip anyway by the instantaneous element in it. Unless someone tapped into the shore power cord, there is no possibility of it suffering an overload condition.

The sort of thing which is really ridiculous is the 30 amp to 15 amp adapters like this Camco 55233 because there is NO overload protection for a 15 amp extension cord above 15 amps.



I can just picture someone coming along and plugging one of these commonplace adapters into the other end of the cord to get 30 amps again.

[enblethen]

The shore power cord is not protected by an appropriately sized over current device.
If something were to happen to shore power cord, transfer switch or rig's wiring between 50 amp receptacle and the rig's main breaker, it could draw the full fifty amp and cause substantial damage and possibly a fire.

[Alan_Hepburn]

WDP wrote:

enblethen wrote:
Most 30 amp rigs have a 30 amp main breaker in the rig.
Yes, there is fifty amps being supplied to the 10/3 shore power cord that is only rated for around 30 amps.

For the electrically challenged in this post, you don't SUPPLY 50 amps, you DRAW 30 amps, this limited by the main breaker in the TT.Perfectly acceptable and SAFE to use a 50 to 30amp adapter.

WDP

Exactly. Think about this: most of the outlets on the walls in your house are protected by a 15A breaker. There is absolutely NO problem with plugging a clock radio, that is designed to use 2A, into that 15A outlet. The ONLY thing that can happen is if the cord itself were to somehow develop a direct short - then it would probably heat up until it tripped the breaker.

If you live your life in fear of a spontaneous short appearing in your shore power cord then maybe you'd be better off camping in a cave with a hole in the ceiling for light and ventilation...

[Wayne_Dohnal]

"Cord must be used in conjunction with a circuit breaker rated 30 AMP" doesn't exactly specify which end of the adapter that the breaker has to be on. In the US, we have readily available 16 and 18 gauge extension cords that plug into 15 and 20 amp outlets. Is that not allowed under the CEC?

[myredracer]

spud1957 wrote:

WDP wrote:

enblethen wrote:
Most 30 amp rigs have a 30 amp main breaker in the rig.
Yes, there is fifty amps being supplied to the 10/3 shore power cord that is only rated for around 30 amps.

For the electrically challenged in this post, you don't SUPPLY 50 amps, you DRAW 30 amps, this limited by the main breaker in the TT.Perfectly acceptable and SAFE to use a 50 to 30amp adapter.

WDP

For those "electrically challenged", the 30 amp breaker in the converter is there to protect the load side of the converter, not the hot side of the converter. That is protected by the breaker at the outside post. The converter itself is capable, as a result of failure, of drawing more than 30 amps.

Section 14 of the Canadian Electrical Code basically says your circuit breaker needs to be sized based on the lowest rated element of the circuit. So if you are using an adapter or cord rated at 30A/125V you are required to use a 30 amp breaker.

Everything will work great until something fails. That's when you want to make sure everything is designed to code. Using an 30A adapter with a 50A breaker is not up to code in Canada. That is why the adapter states a 30A breaker is required!!!

Done.

S

I'm an EE and I don't quite understand your comments. Sure, a main breaker cannot exceed the rating of the panel it is in but by virtue of having a 30 amp breaker at the load end of a 30 amp shore power cord, it's not possible to draw more than 30 amps through it. I'm at a CG and not able to quote anything out of the CEC to show that is okay. You should note though, that the adapters all carry a CSA approval marking on them. If they weren't legal, I'm pretty sure there'd be no CSA approval on them.

If you ask an electrical inspector, you will also find that they do not concern themselves with anything that is plugged in via an extension cord or the cord itself - at least in Canada, unless something has changed recently.

[spud1957]

myredracer wrote:

spud1957 wrote:
Using a cord rated for 30 amps that is plugged into a 50 amp plug is not really the safest way to plug in.

I'm afraid that this is an incorrect statement. A 30 amp RV has a 30 amp main breaker in the converter panel. Because this is at the load end of the shore power cord, it's virtually impossible to draw more than 30 amps through the cord. It is 100% PERFECTLY safe unless you have some really old RV without a main breaker in it.

I guess the adapter manufacturer, Camco, and the Canadian Electrical code are wrong. We should let them know.;)

[myredracer]

spud1957 wrote:
Using a cord rated for 30 amps that is plugged into a 50 amp plug is not really the safest way to plug in.

I'm afraid that this is an incorrect statement. A 30 amp RV has a 30 amp main breaker in the converter panel. Because this is at the load end of the shore power cord, it's virtually impossible to draw more than 30 amps through the cord. It is 100% PERFECTLY safe unless you have some really old RV without a main breaker in it.

[spud1957]

WDP wrote:

enblethen wrote:
Most 30 amp rigs have a 30 amp main breaker in the rig.
Yes, there is fifty amps being supplied to the 10/3 shore power cord that is only rated for around 30 amps.

For the electrically challenged in this post, you don't SUPPLY 50 amps, you DRAW 30 amps, this limited by the main breaker in the TT.Perfectly acceptable and SAFE to use a 50 to 30amp adapter.

WDP

For those "electrically challenged", the 30 amp breaker in the converter is there to protect the load side of the converter, not the hot side of the converter. That is protected by the breaker at the outside post. The converter itself is capable, as a result of failure, of drawing more than 30 amps.

Section 14 of the Canadian Electrical Code basically says your circuit breaker needs to be sized based on the lowest rated element of the circuit. So if you are using an adapter or cord rated at 30A/125V you are required to use a 30 amp breaker.

Everything will work great until something fails. That's when you want to make sure everything is designed to code. Using an 30A adapter with a 50A breaker is not up to code in Canada. That is why the adapter states a 30A breaker is required!!!

Done.

S

[WDP]

enblethen wrote:
Most 30 amp rigs have a 30 amp main breaker in the rig.
Yes, there is fifty amps being supplied to the 10/3 shore power cord that is only rated for around 30 amps.

For the electrically challenged in this post, you don't SUPPLY 50 amps, you DRAW 30 amps, this limited by the main breaker in the TT.Perfectly acceptable and SAFE to use a 50 to 30amp adapter.

WDP

[enblethen]

Most 30 amp rigs have a 30 amp main breaker in the rig.
Yes, there is fifty amps being supplied to the 10/3 shore power cord that is only rated for around 30 amps.

[spud1957]

Using a cord rated for 30 amps that is plugged into a 50 amp plug is not really the safest way to plug in. The 50/30 amp adapter states on the packaging when you purchased it, that it is to be used with a 30 amp breaker.

[myredracer]

This is not all the uncommon. At least all you damaged was your adapter and not the shore power cord. Contributing factors:

1. Loose connection. Worn out receptacle in CG pedestal. Poor connection can cause increased contact resistance. 30 amp receptacles in CG pedestals on average get a lot more use than 50 amps due to the higher number of RVs with 30 amps.

2. Dirty connection. Caused by plugging in the shore power or adapter live all the time. The converter momentary inrush current causes pitting of the plug blades and inside the receptacle. Pitting attracts dirt which together increase the contact resistance. Never plug in live.

3. Low CG voltage along with running your AC unit. Running an AC on low voltage causes the current to increase. You can end up running at or close to 30 amps for extended periods.

It is important to note that you cannot draw more than 30 amps due to the 30 amp main breaker in your converter panel so that is not a factor.

You should periodically check the blades on shore power cords and adapters and clean with fine sandpaper. You can't check inside a receptacle or the female end of your adapter and I don't know of a way to clean pitted contacts inside either. But if the plug blades on an adapter don't look very good, the female end may be bad too.

For those with 30 amp RVs, you can use an 18" 30 amp to 30 amp extender like the Camco #55205 for under $20: This way, if you have no choice in plugging into a crappy and questionable looking CG pedestal, you will only lose the extender and not your shore power cord which could be a disaster when travelling. And again if you have 30 amps, if a 30 amp CG pedestal looks to be poor, it helps to use a 30 to 50 amp adapter because 50 amp recepts. are usually in better shape.

[wilanddij]

Stayed 2 weeks in Floirda. With the 30amp plug with just AC and one other appliance (fan) kept tripping breaker.

So, because the power pole 30A breaker kept tripping, you assumed that hooking to the 50A supply would solve your problem? You melted your dogbone because you continued to draw more than 30A thru the power cords with no over amp protection. The 30A main breaker in your coach should have tripped, but didn't - I would get that checked out before worrying about the dogbone.

BTW, you probably had more units drawing power than mentioned; i.e., Fridge, HW heater, TVs, hair dryer, microwave, toaster, coffeemaker, etc.

[aruba5er]

I always ( when 50 amp is available) use the 50/30 adapter. chances are the 30 amp plug got hot and started burning ever so slightly and then got worse. The most power you can pull is 30 amps because the main in the camper is 30 amps. If plugged into a 100 amp plug the most current you can pull is 30 amps so there is no danger of overloading the supply cord. In the event of a short the 50 amp breaker would trip faster than you can blink. # 14 copper is considered a 100 amp fuse link so it would get darn hot and you could maybe start a fire, but you will never overload a #10 cord because of the inside main of 30 amps. I carry a replacement plug in case mine gets damaged. Too many pedestal outlets are burnt which just compounds the problem