Gdetrailer wrote:
Nvr2Loud writes “You are still wrong.
50 amp two pole breaker on a 240 VAC circuit will only allow 50 amps of total power draw. The breakers are NOT additive. I have no problem with your math, 240 volts x 50 amp is 12,000 Watts, I have a problem with your statement that a 50 amp trailer actually has 100 amp draw. It is a confusing statement, since we don't break down 240 volt appliances by amperage per leg. A 30 amp 240 volt heater will run 15 amp per leg, not 30 amp per leg.
At 240 Volts, the maximum draw is 50 AMP, not 100 AMP.
I see what you are trying to explain, but 50 amp service is 50 amp service, not 100 amp, period.”
You plain don’t get it.
Your are confusing 240V ONLY with 120V/240 SERVICE, there IS a difference.
Here in the States, RVs TYPICALLY DO NOT USE 240V, they USE 120V, the panel ACCEPTS 120V/240V as an input but distributes only 120V.
A RV “50A” shore connection IS NOT USING 240V ONLY, instead they are using as TWO SEPARATE 120V legs at 50A connections and the "service" is known as 120V/240V.
A 50A RV shore connection panel is wired the same way you would like a SUBPANEL. This means there is FOUR WIRES (L1, L2, NEUTRAL, EQUIPMENT GROUND).
L1 and L2 ARE THE 120V “legs” which if you put a meter across those legs you would indeed get 240VAC and if you plugged in a 240V ONLY APPLIANCE you would only get 50A AT 240V…
A meter from L1 to NEUTRAL will read 120V and be capable of 50A (6,000W).
A meter from L2 to NEUTRAL will read 120V and ALSO be capable of 50A (6,000W).
The total amount of 120V load draw you can get is 100A or 12,000W. Granted you are limited to TWO separate 120V draws of 6,000W for a TOTAL of 12,000W but is far more wattage than what a 120V 30A and 120V at 20A can supply.
In a RV you are using TWO 120V legs at 50A EACH LEG (6000W EACH LEG for a TOTAL OF 12,000W)..
120V AT 100A IS 12,000W which IS THE SAME WATTAGE AS 240V AT 50A (12,000W).
This is not the same as grabbing two 50A 120V circuits off the SAME leg, if you used the SAME leg your NEUTRAL MUST BE TWICE THE SIZE (which it is not and I am not bothering to explain that one to you since it most likely would make your head explode..).
A TRUE 240V ONLY appliance (home water heater as an example) there is NO NEED FOR THE NEUTRAL AT ALL. Your RV IS NOT A TRUE 240V ONLY APPLIANCE.
The last time I checked we do not live in Europe so we do not typically have 240V only devices like hair driers, TVs and such, pretty much all normal home electrical devices are setup for 120V.
So, to be extremely clear, using ONE 120V 30A CIRCUIT (Shore cord/panel) AND ONE 120V 20A CIRCUIT (extension cord plugged into a 20A outlet) DOES NOT ADD UP TO A 120V/240V at 50A shore connection. That configuration only gets you HALF THE WATTAGE of a “50A” 120V/240V shore connection.
One 120V at 30A panel and one 120V 20A extension cord only gives you 6,000W (this is equivalent to only ONE LEG or ONE HALF OF THE WATTAGE CAPACITY of a 120V/240V 50A panel).
One 120V/240V at 50A shore connection gives you 12,000W, 120V at30A and 120V at 20A DOES NOT GIVE YOU 12,000W and therefore IS NOT the same..
Your confusion is pretty much normal, many folks can’t understand as to why a 5000W 120V/240V generator will not have enough power to start their A/C..
The reason.. 120V usage you only are using ONE leg of the gen which can only provide ONE HALF the rated output of the 5K gen for EACH leg.. Basically the gen only supplies 2500W of the 5Kw on EACH 120V outlet (leg).
Gdetrailer wrote:
Nvr2Loud writes “You are not correct. A 50 amp 240 volt shore power breaker is capable of producing 50 amp maximum (not 50 amp per line)
If it was DC current, you would be correct, however it is AC current we are discussing.
An entire house with dual 100 amp main breakers is capable of running 10 amps total, not 200 amp.”
:R :h :E ??
Sorry but you are wrong.
240V requires a double pole breaker, this breaker is designed with a common trip for BOTH “poles”, the poles are Line1 and Line 2. EACH “POLE” of the breaker is rated for 50A.
Keep in mind 240V x 50A is 12,000W.
120V x50A is 6,000W
Each pole (line) on a double breaker is to protect the 120V LINE on that pole.
The 240V from the utility comes from a transformer, L1 and L2 come from the ENDS of the transformer windings.
To get 120V you NEED to provide some sort of split in the voltage, this is done at the transformer via what is known as a CENTER TAP.
The CENTER TAP IS USED AS THE NEUTRAL WIRE.
So if you looked at the waveform from the neutral you would see that the L2 peaks are the OPPOSITE of L1.
Think of it like you have two 6V batteries in series and the center tap of the transformer is the connection in between the two batteries.. Only in this case we are dealing with alternating current.
I would suggest you study the diagram below..
In the AC world the two 120V lines are in series to provide 240V and the center tap allows us to get TWO 120V lines.
Typically in a RV there are no 240V “appliances” and what you get is TWO 120V AT 50A lines (although you could potentially add a 240V device).
The last time I checked, TWO 120V lines at 50A IS 12,000W..
Not sure where you were going with the last part but it is not correct either..
A home service load center which is 100A is not “dual breakers”, they are TWO POLE breakers with a common trip and EACH pole handles 100A at 120V. EACH pole handles 12,000W and for 240V you get 24,000W for that panel.
I would highly recommend you take a real good look at the following link which will explain why you are wrong.. (it is where I found the diagram above but the link has text for you to follow along with)
HERE
In the mean time I would recommend that you should not start poking you fingers inside any electrical box..
Gdetrailer wrote:
I didn't want to confuse the already confused Nvr2loud with the idea of SUBPANELS and the rules on how they must be wired.. :S
Gdetrailer wrote:
....This creates a issue of not many circuits to do things with.. So what tends to happen is most circuits will do multi-tasking.. You will often find several circuits powering all the outlets, one for A/C. The converter often "shares" with another circuit..
