Total 50 AMPS or Across both lines?

[TurnerFam]

Originally Posted by cavie

What you all tell the newbies is 100 amps of power. But when one leg goes over 50 amps and trips the breaker they stand back and say What the hell... They also need to know that there is 240 volts present in that panel. Not just 2 120 volt legs.

this is why your are confusing 'home electrical' with 'rv electrical'... the simple answer is that the far majority of any 50amp RV's MAIN PANEL have incoming 240v power, from the 50amp Shore Power outlet and thru the Shore Cord, but the RV's main panel does NOT combine the two, or ALLOW the two to be combined for any 240v output. A home's 240v panel allows for double-pole 240v breakers, but an RV's typically does NOT.
Are there exceptions? Yes. If you are talking about a larger coach with a 240v clothes dryer, then certainly, that coach will have more of a 'home' type Main Panel, with 240v breakers.
The vast majority do not, and simply make use of both 'sides' of the incoming 50amp 240v power separately, as TWO DIFFERENT 120v POWER SOURCES. Just because one 'side' can be overloaded and the tripping of that side causes both 'sides' to then trip together doesn't effect the overall 100amps of usable power - a coach owner is already 'assigned' breakers for the circuits on each 'side' to be 'balanced', though it's never a perfect science in a situation, like an RV, where the main panel is controlling many differing loads.

I also don't think that just because we use the term '100amps of usable 120v power' is going to somehow make some owner decide to 'go into their main panel and start moving stuff around', or such, but I get your concern, though I think it's over reaching for the simple conversation about the true 'reality' of RV power.

[cavie]

Originally Posted by TurnerFam

this is why your are confusing 'home electrical' with 'rv electrical'... the simple answer is that the far majority of any 50amp RV's MAIN PANEL have incoming 240v power, from the 50amp Shore Power outlet and thru the Shore Cord, but the RV's main panel does NOT combine the two, or ALLOW the two to be combined for any 240v output. A home's 240v panel allows for double-pole 240v breakers, but an RV's typically does NOT.
Are there exceptions? Yes. If you are talking about a larger coach with a 240v clothes dryer, then certainly, that coach will have more of a 'home' type Main Panel, with 240v breakers.
The vast majority do not, and simply make use of both 'sides' of the incoming 50amp 240v power separately, as TWO DIFFERENT 120v POWER SOURCES. Just because one 'side' can be overloaded and the tripping of that side causes both 'sides' to then trip together doesn't effect the overall 100amps of usable power - a coach owner is already 'assigned' breakers for the circuits on each 'side' to be 'balanced', though it's never a perfect science in a situation, like an RV, where the main panel is controlling many differing loads.

I also don't think that just because we use the term '100amps of usable 120v power' is going to somehow make some owner decide to 'go into their main panel and start moving stuff around', or such, but I get your concern, though I think it's over reaching for the simple conversation about the true 'reality' of RV power.

You are preaching to a 69 year old Master Electrician with 55 years experience that is NOT gonna change his mind about how to explain electricity to newbies Sorry!!

[lwmcguire]

Originally Posted by cavie

What you all tell the newbies is 100 amps of power. But when one leg goes over 50 amps and trips the breaker they stand back and say What the hell. IF you want to use the terms 100 amps of power( witch an electrician will never say) at least have the decency to explain that it will trip with over 50 amps on one leg. If a newbie decides to move wires around in the panel and puts too much load on one leg that is exactly what will happen. You need to tell them how to balance a panel! They also need to know that there is 240 volts present in that panel. Not just 2 120 volt legs.

My Coach and all the larger class A's have load management systems that unload in the event the max is possible and prevent the trip

[cavie]

I had a Moderator on a Face Book RV Site who works in an RV repair facility and has a Blog tell me that electricians do screw up and put 240 volts down one leg of an RV service and blow everything up. In the US that is impossible to happen. A newbie reads that from an RV tech and thinks it for real!!!!

[cavie]

Originally Posted by lwmcguire

My Coach and all the larger class A's have load management systems that unload in the event the max is possible and prevent the trip

Yep but there are 100's of 1000's of RV's that don't have that.

[lwmcguire]

Originally Posted by cavie

Yep but there are 100's of 1000's of RV's that don't have that.

I could definitely see that being a challenge

Sure remember the 30 amp days for darn near 50 years

We often have the Fireplace or Central Vac kick off due to loading when using the heat pumps or other heavy current draw appliances

Perhaps the load management systems appear more often with three HVAC Coaches, which is certainly where they are needed

[Chance]

Originally Posted by TurnerFam

long but well drawn-out conversation about 'lectricity! Love it...

yes, master electricians and those in the trade will side with the 'what the breaker says is what you have' philosophy, but those of us in the 'real world' of RVs eventually learn to understand that '50amps' ain't the same as what electricians would explain it as. No matter how you 'say' it, an RV with a 50amp Main Panel, with only 120v single pole breakers for all it's circuits, plugging into a 50amp RV outlet, is going to have a range of up to 100amps of 'usable' 120v power, not just 20 more than a more typical 30amp RV outlet, though by the terminology we use, you would think so, at least initially.


.....cut.....

That’s what often happens when people oversimplify things in the name of brevity.

It seems the message you are trying to convey is that an RV 50A service is far more capacity compared to an RV 30A service than the numbers 50 versus 30 suggest, and of course it is. However, if one says that 50A is 100 Amps equivalent, then it could be a little misleading to a clueless person because there is no easy way to plug in a 60-Amp 120-Volt load.

Instead of saying 100 Amps, it may confuse beginners less if one said “two” 50-Amp services (although not technically correct).

My personal preference to communicate the systems’ differences in capability would be to express it in units of Watts rather than Amps. Therefore, an RV 30A service has “up to” 3,600 Watts of capacity, and an RV 50A “up to” 12,000 Watts.

Comparing 3,600 to 12,000 Watts immediately sends the message that one is far more capable without getting into details that may confuse.



Using units of power rather than current also helps relate electrical availability when RV is running off generator. A large 50A motorhome with a typical 5,500-Watt Onan can therefore only power up to 5,500 Watts and not 12,000 Watts.

If we said the 5,500-Watt Onan generator can provide up to 46 Amps, then a newbie may compare to 50A service and think he’s most of the way there.