Pulling more than 50 amps ?

wa8yxm wrote:

Gdetrailer wrote:

You however cannot "combine or connect" L1 and L2 together because they are out of phase (one positive and one negative going). Adding two voltages out of phase CANCELS the voltage and in this case creates a huge short and the result would be zero volts.

Though you are correct. 100% and that was a good post I will comment on this paragrapy.
Wrong point of view
When we talk about "Combining" we mean one leg is fed to the OUTLET so there is L-1 and L-1 not L-1 and L-2
You were looking at it from the other side. You are correct that if you try to hook L-1 to L-2 smoke fire and sparks (or tripped breakers) will ensue.

But some "Cheater Parks" only run one leg to the box or so I'm told.

The key is "so you been told"..

There is no way ANY park which has a 50A 120/240 socket could have connected only ONE hot to both L1 and L2 terminals in the box and have been "legal". That would have had to be an pirate connection, I think you have been told a few "tall tales" from folks who don't understand how the mysteries of electric work.

Why?

Simple, using only one of the split phases can easily overload the NEUTRAL wire on your shore cord and even the campgrounds own Neutral.

That would never have passed the POCOs inspector and the POCO REQUIRES ALL connections to the grid to be INSPECTED before any power is applied.

The split phase setup allows one to use the same size neutral wire as the hot phase (L1 and L2). This is because the voltage and current on the L1 and L2 are 180 degrees. The same thing as the voltage, the current on L1 goes up when the current on L2 goes negative. That has the effect of canceling out the current seen on the neutral.

To visualize this you would have to imaging having only a purely restive load like say two 120V 100W incadescent bulbs wired in series. The voltage and current are evenly divided and flowing only on L1 and L2 and zero current would be flowing on the neutral (balanced circuit).

Now, if one of the 100W bulbs were to be replaced with a 50W bulb, you would have an unbalanced circuit and because you have the neutral the 100W bulb still pulls 100W and the 50W bulb pulls 50W and the neutral will have 50W on it..

In your example, using only one of the Split phases two 100W bulbs are in parallel and the neutral carries full 200W. Very easy to overload the neutral.

Combining L1 and L2 on the shore power socket would mean the Neutral would now see a potential of a 100A worth of current (basically paralleling the TWO 50A breakers) , that is going to cause fires. Campground would end up being liable and on the hook for burning down someones RV..

Now, if you are talking those portable "cheater boxes" where you use a 30A 120V and 20A 120V plug in to the shore power, 30A and 20A add up to 50A and will not overload the neutral.. Those CAN use the SAME phase or L1 and L2 but in most more modern parks you WILL run into issues with the 20A plug in having a GFCI which will most likely not like that setup and be a tripping issue.