50 amp to 30 amp adapter

Stovepipe wrote:

CavemanCharlie wrote:

SoundGuy wrote:

rbpru wrote:
For the technically inclined, the 50 amp plug has two 120 volt lines available which can be combined to power the heavier electrical loads of a 50 amp TT.

CavemanCharlie wrote:
Um,, this doesn't sound right to me. If you combine two 120 volt lines you get 240 volts. No RV I've ever seen runs off of 240 volts.

I may be miss interpreting you though.

CA Traveler wrote:
The 50A RV circuit is 120/240V 50A and it does indeed supply both 120V and 240V to the RV.

Most RVs don't have 240V appliances but some do. But for the technically inclined it is NOT just 2 120V circuits. Rather it's a split phase design such that the neutral carries the difference in amps of the two hots and hence cannot exceed 50A. The circuit is identical to a home 50A oven for example.

The above as written could suggest to some that "50 amp RV service" can only handle a maximum load of 50 amps when in fact it's 100 amp service across 2 out of phase legs with a common neutral, offering 12,000 watts of power vs just 6000 watts for a true single phase 50 amp service, 3600 watts for single phase 30 amp service, 2400 watts for single phase 20 amp service, and 1800 watts for single phase 15 amp service. Ideally this so-called 50 amp service will be installed in any coach so the anticipated loads will be somewhat balanced - e.g. with dual A/Cs one will be wired across the hot and neutral of one leg, the second A/C across the hot and neutral of the second leg. Any suggestion that this service offers a maximum load capability of just 50 amps (6000 watts) is simply incorrect.

Thank you. Though, with my Caveman brain I would have to set down and study all of this closely to understand it well. Because I don't have the need to know this knowledge at this time I think I will just try to save my limited brain space for other things.

Have a nice Day.

LOL I read your post in this guy's voice:

lol

But, I don't know where that picture came from.

CavemanCharlie wrote:

SoundGuy wrote:

rbpru wrote:
For the technically inclined, the 50 amp plug has two 120 volt lines available which can be combined to power the heavier electrical loads of a 50 amp TT.

CavemanCharlie wrote:
Um,, this doesn't sound right to me. If you combine two 120 volt lines you get 240 volts. No RV I've ever seen runs off of 240 volts.

I may be miss interpreting you though.

CA Traveler wrote:
The 50A RV circuit is 120/240V 50A and it does indeed supply both 120V and 240V to the RV.

Most RVs don't have 240V appliances but some do. But for the technically inclined it is NOT just 2 120V circuits. Rather it's a split phase design such that the neutral carries the difference in amps of the two hots and hence cannot exceed 50A. The circuit is identical to a home 50A oven for example.

The above as written could suggest to some that "50 amp RV service" can only handle a maximum load of 50 amps when in fact it's 100 amp service across 2 out of phase legs with a common neutral, offering 12,000 watts of power vs just 6000 watts for a true single phase 50 amp service, 3600 watts for single phase 30 amp service, 2400 watts for single phase 20 amp service, and 1800 watts for single phase 15 amp service. Ideally this so-called 50 amp service will be installed in any coach so the anticipated loads will be somewhat balanced - e.g. with dual A/Cs one will be wired across the hot and neutral of one leg, the second A/C across the hot and neutral of the second leg. Any suggestion that this service offers a maximum load capability of just 50 amps (6000 watts) is simply incorrect.

Thank you. Though, with my Caveman brain I would have to set down and study all of this closely to understand it well. Because I don't have the need to know this knowledge at this time I think I will just try to save my limited brain space for other things.

Have a nice Day.

LOL I read your post in this guy's voice:

SoundGuy wrote:

rbpru wrote:
For the technically inclined, the 50 amp plug has two 120 volt lines available which can be combined to power the heavier electrical loads of a 50 amp TT.

CavemanCharlie wrote:
Um,, this doesn't sound right to me. If you combine two 120 volt lines you get 240 volts. No RV I've ever seen runs off of 240 volts.

I may be miss interpreting you though.

CA Traveler wrote:
The 50A RV circuit is 120/240V 50A and it does indeed supply both 120V and 240V to the RV.

Most RVs don't have 240V appliances but some do. But for the technically inclined it is NOT just 2 120V circuits. Rather it's a split phase design such that the neutral carries the difference in amps of the two hots and hence cannot exceed 50A. The circuit is identical to a home 50A oven for example.

The above as written could suggest to some that "50 amp RV service" can only handle a maximum load of 50 amps when in fact it's 100 amp service across 2 out of phase legs with a common neutral, offering 12,000 watts of power vs just 6000 watts for a true single phase 50 amp service, 3600 watts for single phase 30 amp service, 2400 watts for single phase 20 amp service, and 1800 watts for single phase 15 amp service. Ideally this so-called 50 amp service will be installed in any coach so the anticipated loads will be somewhat balanced - e.g. with dual A/Cs one will be wired across the hot and neutral of one leg, the second A/C across the hot and neutral of the second leg. Any suggestion that this service offers a maximum load capability of just 50 amps (6000 watts) is simply incorrect.

Thank you. Though, with my Caveman brain I would have to set down and study all of this closely to understand it well. Because I don't have the need to know this knowledge at this time I think I will just try to save my limited brain space for other things.

Have a nice Day.

SoundGuy wrote:

rbpru wrote:
For the technically inclined, the 50 amp plug has two 120 volt lines available which can be combined to power the heavier electrical loads of a 50 amp TT.

CavemanCharlie wrote:
Um,, this doesn't sound right to me. If you combine two 120 volt lines you get 240 volts. No RV I've ever seen runs off of 240 volts.

I may be miss interpreting you though.

You are. So-called "50 amp RV service" is actually 100 amp service across two 120 vac legs which when measured from hot to hot measures 240 vac. Any rig wired with "50 amp service" is wired so part of the load will be on one 120 vac leg and part on the other 120 vac leg. In large rigs that may be equipped with a washer & dryer the dryer may be wired across both legs or 240 vac just as it would be in your home.

OK , I get that and thank you

There may be more interested parties on these boards than elsewhere and it's good to help those that want to know. 50A RV power will continue I'm sure as it has in the past many years to be not well understood.

CA Traveler wrote:
And turn the breaker off before unplugging. It's also safer just in case you get in contact with the prongs or it's wet. Many many sites we've been in tend to have damp ground near the pedestal.

This is what I do. I don't worry about plugging in since my hardwired PI EMS 50 won't allow power to the trailer for 15 seconds and its checked voltage, polarity, ground, and hertz. I do turn the breaker off when I unplug though because if you do touch a prong it could hurt bad or worse.

Or you could install a 20 amp 120 volt power inlet to a 30 amp RV and get 50 amps... :B

One thing many people don't know is that the NEC only requires min. 20% of an RV park/CG to have 50 amp pedestals. In 2002, it was only 5% required. It may be nice to have a 50 amp RV, but it can be next to impossible to find a site with 50 amps available. Older CGs can have no 50 amp pedestals. RV dealers and manufacturers never tell you that. The NEC needs to catch up to all the 50 amp RVs that are being sold nowadays.

CA Traveler wrote:
Sound Guy - good links.

Most RVers don't care about the electrical specifications and know that 50A can supply more power than they can use and they don't care about the details. Labeling doesn't really matter as there is one and only one 50A RV circuit.

And therein lies the rub - while I'd agree completely that most RVrs don't care about the details the reality is that by "not knowing" they're also not understanding that "50 amp RV service" is in fact considerably more substantial than single phase 30 amp RV service - 12,000 watts vs 3600 watts, or ~ 3.333 times more. Therefore I'd disagree about labeling which IS important, as the current methodology, 'though it may make perfect sense to you and I, clearly confounds many users into believing that 50 amp RV service is simply 20 amps more than the so common 30 amp service, which is not the case at all. Hopefully discussions like this, as detailed as they may sometimes get, will help clarify just what "50 amp RV service" really means. ;)

Sound Guy - good links.

Most RVers don't care about the electrical specifications and know that 50A can supply more power than they can use and they don't care about the details. Labeling doesn't really matter as there is one and only one 50A RV circuit.

But in the electrical world with many possible 50A circuits it is a 120/240V 50A 3 pole 4 wire 60HZ single phase circuit. Incorrect labels line 2 phase and 100A circuit are in wide spread use in the RV world and I'm sure will remain that way.

In the RV world it's reasonable to think of it as having 2x 120V 50A capability.

In the electrical world it's known that the 50A label applies to the higher voltage. It's also a fact that the circuit can supply any combination of both 120V and 240V as long as neither hot leg exceeds 50A. The design is also such that the center tapped neutral will carry the difference between the hots and hence never exceed 50A.

Midnightpumpkin wrote:
Yes it is ok to use the 50 amp adaptor. The 30 amp main circuit breaker in your unit will protect your wiring.

John U

Not completely accurate since you 30A shore power cord and the wiring inside the trailer up to the main 30A CB is typically 30a so those two are not properly protected. However, the risk is fairly small so go ahead IMO and use the adapter.

Larry