50 amp.... Why so big?

[el Rojo]

@xrated here's a question about out of phase. Take the tetter totter example. So all the neutrals from both sides are combined? And the hot legs, L1 and L2 send short pulses of current (very quickly) at different times?

or

Are the neutrals from each leg kept separate?

This is a very good thread. Thanks for posting.

Red

[BobLandry]

There is only one neutral as both L1 and L2 are being derived from the same outlet. Both 120V legs reference to that one neutral which is fine sine the two legs are 180 degrees out. If you were in a configuration where you were using two 30A sources as is standard in marine use( I have not seen this at a campground), Both legs would have it's own dedicated neutral. Even though the power would be taken from the same pedestal, there is no guarantee that the two hot legs would be exactly 180 degrees out of phase. You would never tie neutrals together at the panel when using two power sources.

[xrated]

@xrated here's a question about out of phase. Take the tetter totter example. So all the neutrals from both sides are combined? And the hot legs, L1 and L2 send short pulses of current (very quickly) at different times?

or

Are the neutrals from each leg kept separate?

This is a very good thread. Thanks for posting.

Red

Yes, there is only one neutral and it carries current from each of the two phases, but the neutral current never goes over 50 amps....ever.

[el Rojo]

There is only one neutral as both L1 and L2 are being derived from the same outlet. Both 120V legs reference to that one neutral which is fine sine the two legs are 180 degrees out. If you were in a configuration where you were using two 30A sources as is standard in marine use( I have not seen this at a campground), Both legs would have it's own dedicated neutral. Even though the power would be taken from the same pedestal, there is no guarantee that the two hot legs would be exactly 180 degrees out of phase. You would never tie neutrals together at the panel when using two power sources.

So is my first example correct?

Red

[xrated]

Keep in mind folks, my example of the teetor totter is not a totally accurate description of how it works, and probably a poor example or explanation, and in fact...I deleted it entirely. The true result of a split phase setup with a totally balanced load scenario would actually be zero current on the neutral wire if both hot legs were in fact supplying the same amount of current.....they would actually cancel each other out.....sorry for the confusion....it was my feeble attempt to try and explain it. Hopefully, our resident Electrical Engineer will pop in and offer a better explanation than mine.

[Wicked ace]

I'm sure the electrical load has the most to do with it. My 260RD will get along just fine on a 30 amp outlet at the post. I've run the A/C and microwave while watching TV without a hiccup when that was all that was available yet I have 50 amp socket on the side of my trailer. The only justification I can come up with is the bedroom vent is prepped for a second A/C unit. I have found no need to get one but I'm sure the added load would be too much for a 30 amp service.

[AZMike]

Maybe I missed it, but I did not see this issue addressed. If you have a 50A rig, but only 30A service available at the pedestal, you would use a 30A male to 50A female adapter. If the two 50A legs in the distribution panel are separate, how does the power get to both legs? The only (simple) way I see possible is to tie the two legs together in the 30A to 50A convertor, correct?

FYI, I don't have 50A in my rig, I couldn't afford it!

[Wicked ace]

Maybe I missed it, but I did not see this issue addressed. If you have a 50A rig, but only 30A service available at the pedestal, you would use a 30A male to 50A female adapter. If the two 50A legs in the distribution panel are separate, how does the power get to both legs? The only (simple) way I see possible is to tie the two legs together in the 30A to 50A convertor, correct?

FYI, I don't have 50A in my rig, I couldn't afford it!

The "Dogbone" adapter crosses and makes both hot legs a common feed.
https://www.homedepot.com/p/Camco-18...5183/302483391

[Roll With The Changes]

Keep in mind folks, my example of the teetor totter is not a totally accurate description of how it works, and probably a poor example or explanation, and in fact...I deleted it entirely. The true result of a split phase setup with a totally balanced load scenario would actually be zero current on the neutral wire if both hot legs were in fact supplying the same amount of current.....they would actually cancel each other out.....sorry for the confusion....it was my feeble attempt to try and explain it. Hopefully, our resident Electrical Engineer will pop in and offer a better explanation than mine.

I like to use plumbing as an analogy for electrical theory because it has so many parallels. Let's see if it works here:



In the picture are three water tanks labeled L1, N, and L2. Load 1 and two are pumps that can pump in either direction. If Load 1 pumps from tank "L1", it will pump into tank "N". If it is reversed, it will pull water from tank "N". The same is true for Load 2. However, if both "Loads" are pumping in the same direction (meaning left to right for example), water will move from tank "L1" to tank "L2" with no change in tank "N". If both pumps are reversed, water moves from L2 to L1, again with no change to tank "N".

All of this depends on both pumps moving in the same direction and at the same flow rate. If one pump is pumping faster than the other one, water will move either to or from tank "N". This is what @xrated referred to as "legs having the same load." The direction that the pumps are flowing is referring to the legs being 180 degrees "out of phase" As long as all of that is true, there is no flow in pipe "N" or the neutral.

Now look at the extreme cases. Suppose pump "L1" is pumping 50 gallons per minute (50 amps) and L2 is not pumping at all. The flow in pipe "N" will be 50 GPM or 50 amps. The same is true if you reverse it to make L2 pump and L1 not pump (unbalanced loads). Also, if for some reason, the pumps ran in opposite directions, the flow in pipes "L1 and L2" would each be 50 GPM but pipe "N" would flow at 100 GPM! Obviously, that would be catastrophic for the pipe and for the neutral wire. As @xrated said, as long as the two legs are 180 degrees out of phase, the neutral cannot possibly see higher current than either of the line currents. Luckily, if you are plugged in to a single outlet, the legs will ALWAYS be 180 out of phase.

Let me know if that analogy made sense.

[gbkims]

Since I've been working with my home CB panel I was measuring the panel's service conductor Amps with a clamp on.
Running A/C, Clothes Dryer and several other appliances: L1 = 51A, L2 = 44A, Neutral = 7.8A