30A to 50A Step Up Transformer?

[Route 66]

enabling coaches with 50A service to have full use of RV appliances.

It's just not true. You cannot have full use of all appliances. It may well provide 50A @ 120V, but standard 50A RV service provides TWO 50A circuits @ 120V for a total of 100A.

[Ray,IN]

Those "cheater boxes" will only work if each outlet is on a different circuit.

[WindRVer]

Man, I know I'm picking here, but since we're all being so technical... When you are using two phases, it is true, they are out of phase with each other, by 120 degrees, not 180. All major generators are 3 phase, and provide power to the grid as three phases. Since generators move in a circular motion (rotation), and there are 3 phases, they are equally spaced apart. 360 / 3 = 120 degrees, not 180. All the rest is correct.

Again, sorry to pick, I just see that error all over these boards.

[RustyJC]

The 2 hot legs (L1 and L2) are 180 degrees out of phase since they come from a center-tapped neutral transformer. The center tap means that an AC current sine wave is flowing through the output side transformer from L1 to N at the same time it's flowing from N to L2. This puts the two legs 180 degrees out of phase.

An explanation of this split-phase power is given HERE.

Rusty

[WindRVer]

A center tap transformer uses two legs of ac, which still means they are 120 degrees from each other. Not 180. Sorry.

[RustyJC]

From the article I cited above:

Since there are two live conductors in the system, it is sometimes incorrectly referred to as "two phase". The two live or "hot" conductors waveforms are offset by a half-cycle, or 180 degrees offset, when measured against the neutral wire.

360 degrees divided by 2 = 180 degrees apart in a split-phase system, not 120.

Sorry.

Read the article and see that the split-phase system splits a single phase of AC power; thus, the 180 degree separation.

Rusty

[azloafer]

First they CANNOT exist.
Then ads from CW & Tweety's show they DO.
Then they might exist, BUT they cannot work.
Three people on CW site say they DO work.
Then they might work a little, but NOT "enough".
Then they will work if the circuit is correct,
Or maybe not?

[RustyJC]

Stop and think about it. If one of the 50 amp legs is fed by a 30 amp circuit and the other 50 amp leg is fed by a 20 amp circuit, how can either 50 amp leg provide 50 amps without tripping the pedestal supply-side breaker (30 and 20 amps respectively)? There's certainly no way that both 50 amp legs can provide 50 amps with one of these cheater boxes.

Rusty

[Route 66]

Originally Posted by azloafer

First they CANNOT exist.
Then ads from CW & Tweety's show they DO.
Then they might exist, BUT they cannot work.
Three people on CW site say they DO work.
Then they might work a little, but NOT "enough".
Then they will work if the circuit is correct,
Or maybe not?

That one statement is correct.

[WOODYDEL]

There's a lot of baloney flying around here. It's actually a hopeless case of total misinformation. Let me rephrase that. I would not use this as a reference. That's not to mention the stealing of the extra power you are not paying to use if some of the schemes worked. Most won't.

Remember there is a campground owner trying to make some money. Like my good hearted friend Charlie. Who can't afford those million dollar rigs which need so much power.


Couple of weeks ago I was posting about winter coming. I found a site whose owner did winter camping and basically laid out the how to do its. Well I did not link his site for one reason. He mentions taking power from adjacent sites to power his heaters. Says the rangers don't really care. What?! Well if I had posted that site link I'm reasonably sure he would have gottem more hate email than he would want. So I spared him and myself. (no link will be provided)

[Theberrys]

Who cares about 240VAC. What appliances does anyone have that require 240VAC. everything in my coach is 120VAC. So it really doesn't matter what the Phase of the two lines is. If a adapter can plug into a 30 AMP and a 20AMP feed and provide a total of 50 AMP that may be better as long as the 20 AMP line is feeding the least loaded circuit in the Coach.

The real misnomer is the term 50 AMP Hookup. There is no such thing. There are 15 AMP, 20 AMP, 30 AMP, and 100 AMP services in most parks. People spend a lot of money buying test equipment to insure there coach is safe from a 50 AMP hookup.

So pick the nits if you must but Joe is correct in some parks you can feed one 120 VAC circuit in your coach with a 30 AMP Service and the other 120VAC circuit in your coach with a 20 AMP service, and finally get the 50 AMPS everyone has been talking about all these years. There is no need to have the two feeds out of phase by 180 or 120 degrees. And as long as the breakers don’t pop it doesn’t matter if they are the same circuit from the transformer, they will still charge your Droid.

Dick

[RustyJC]

Originally Posted by Theberrys

Who cares about 240VAC?

With all respect, anyone with 50 amp service in their RV had BETTER care since, if the 50 amp service hookup is miswired such that L1 to L2 reads 0 VAC instead of 240 VAC, there could be as much as 100 amps flowing through neutral conductors that are sized for 50 amps with the resultant electrical and fire risks!

By the way, some high-end coaches do have 240 VAC appliances.

Rusty

[WindRVer]

Rusty,

Thanks for the article. I will look further into this for my own education. Something is still not right with the math, though (to me). Splitting a 120 degree waveform to produce 180 degree separation doesn't make sense to me yet. As I said, I'll look into it more.

[RustyJC]

You're splitting a single phase sine wave that has a 360 degree period, so half of 360 is 180 degrees.

Remember, the feed to the transformer is only one phase, not 3.

Rusty