Stupid amps question

[kenandterry]

It’s either the heat and humidity today....or it’s a COVID side effect.....

If I plug into a standard RV 50amp receptacle, with a male dogbone down to a 30amp female socket, the RV connected using a 30amp plug is capable of “pulling” 50amps of power right?

I think I’m losing it

[MtBiker]

It should. You will only have one 50 amp leg and your breaker would then limit it to 30 amp.

[CHICKDOE]

the limiting device will be the 30 amp main circuit breaker in the rv. it should trip whenever the rv loads exceed 30 amps. under this situation the 50 amp breaker that you are plugged into will not trip (unless you have a short in the power cable before it gets to the 30 amp breaker).

[DougW]

Originally Posted by CHICKDOE

the limiting device will be the 30 amp main circuit breaker in the rv. it should trip whenever the rv loads exceed 30 amps. under this situation the 50 amp breaker that you are plugged into will not trip (unless you have a short in the power cable before it gets to the 30 amp breaker).

What he said is right.

[kenandterry]

Thanks so far.

I have a 50amp RV receptacle on our property.
I’m hoping to have friend arrive here with his new 50amp motorhome, but I wanted to have him see what he can and cannot run with 50 or 30 or 20amp receptacles to his rig.

[Reverse_snowbird]

Originally Posted by kenandterry

Thanks so far.

I have a 50amp RV receptacle on our property.
I’m hoping to have friend arrive here with his new 50amp motorhome, but I wanted to have him see what he can and cannot run with 50 or 30 or 20amp receptacles to his rig.

Thanks for clarifying that. I was suffering from a little brain fog myself since you seem to have a 50amp rig.

[GoneSouth10]

No such thing as a "stupid amp" . . . My suggestion would be, once your friend arrives, to consult with Professor Alexander Keith for a couple of hours . . . those amps will soon appear smart by comparison.

[CHICKDOE]

how are you going to connect for the 20 amp test? if you plug into the 50 amp pedestal and use adapters to get a standard 20 amp receptacle powered you will then have to use another adapter to get back to a 30 amp receptacle that he can plug into. there is no way to actually limit the current flow to only 20 amps since you have a 50 amp breaker at the pedestal and a 30 in the rv. so you could be running more than 20 amps that might overload any cable or adapter designed for only 20 amps.

[jeff64]

Originally Posted by CHICKDOE

how are you going to connect for the 20 amp test? if you plug into the 50 amp pedestal and use adapters to get a standard 20 amp receptacle powered you will then have to use another adapter to get back to a 30 amp receptacle that he can plug into. there is no way to actually limit the current flow to only 20 amps since you have a 50 amp breaker at the pedestal and a 30 in the rv. so you could be running more than 20 amps that might overload any cable or adapter designed for only 20 amps.

Like he said, your smallest rated component in the hookup is your limiting factor. Think wire gauge

[wanderingbob]

The amps that you do not use are let out in the campground . Late at night if you are quiet and have your lights off
you can see them sneaking around causing all kinds of mischief . letting air of trailer tires , clogging sewer lines and eating any food left out ! Beware !

[bubbles]

If your only pedestal receptacle is a 50Amp and if you only use that as the power source for whatever amperage (any combination of dog bone reductions) you want to demo there will always be 50Amps to the friends 50Amp RV. You cannot change power by simply inserting a dog bone.

[TitanMike]

Originally Posted by wanderingbob

The amps that you do not use are let out in the campground . Late at night if you are quiet and have your lights off
you can see them sneaking around causing all kinds of mischief . letting air of trailer tires , clogging sewer lines and eating any food left out ! Beware !

You left out pulling hitch pins and folding hand rails scross doors [emoji41]

[SlowrideHD]

The safe thing is to have a short 10 gauge extension cord when doing the adaptor tests. As mentioned, if your dogbones are 30 amp, It can be possible to overload a regular HD 12 gauge extension cord without tripping a 30 amp breaker.
I once saw a neighbor in a campground get an extension cord so hot that it was melting the covering off. They were running their a/c and no telling what else. His dog had chewed his regular 30 amp cord.

[wmtire]

Originally Posted by kenandterry

If I plug into a standard RV 50amp receptacle, with a male dogbone down to a 30amp female socket, the RV connected using a 30amp plug is capable of “pulling” 50amps of power right?

Originally Posted by kenandterry

Thanks so far.

I have a 50amp RV receptacle on our property.
I’m hoping to have friend arrive here with his new 50amp motorhome, but I wanted to have him see what he can and cannot run with 50 or 30 or 20amp receptacles to his rig.

You are not going to be able to run an accurate test this way. You are going to need an outlet (or even an RV) with a 30 amp and 20 main breaker to do this.

Just using adapter from a NEMA 14-50 outlet (as you stated you have on your property) will not accomplish this.

In your first test, adapting from the NEMA 14-50 out to a NEMA 30TT receptacle then adapting from the NEMA 30TTR back to a NEMA14-50R will allow one 50 amp leg to be shared to the RV's distribution panel. You cannot test for 30 amps this way and have no circuit breaker to protect/trip when going over 30 amps total.

Same thing goes for adapting from NEMA 14-50 to a NEMA 5-20. You will still have one leg of 50 amps powering the RV...with no circuit breaker anywhere to protect/trip when going over 20 amps total.


Since your friends RV utilizes a 120/240 split phase service (NEMA 14-50) with two hot legs each at 50 amps, he has no circuit breakers in his RV's distribution panel to trip when he exceeds 30 or 20 amps total.


You would need to use adapters to plug into a campground pedestals 30 or 20 amp outlets, which would have their own 30 or 20 amp circuit breakers on the pedestal itself to test for this. It doesn't sound like you have that on the pedestal at your house.

[Scrapper]

Originally Posted by TitanMike

You left out pulling hitch pins and folding hand rails scross doors [emoji41]

Don't forget drinking water from neglected deep cycle batteries. Kinda funny they don't bother the regular battery in your tv. Must have something to do with the high CCA.