Shore Line Power Upgrade

[imob]

Hi Folks, I am new to RV'ing but very familiar with electrical, plumbing, cabinet making and such.

RV: 2000 Winne Brave SE 31'

Here is the issue, I know its a common one. I have 2 AC units, a 30 amp panel, and a 45 amp gen. When on shore power I can run 1 AC (on switch front or back) when I am on gen I can run both AC units on the same 30 amp plug/cord.

I want to upgrade the shoreline to a 50 amp with a transfer switch. Really all I care about is being able to run both AC on shore power.

My question is how in the heck is this thing wired? Yes this was a factory install. The rear AC is not hot to the gen outlet because of the internal switch. Additionally the power block (yes this what I call the fuse block/inverter/12v transfer switch) must be able to sense the difference in power inputs because if I try to turn on the 2nd AC it prevents it when on 15/30 amp shore power.

*For note I opened the shore power/gen outlet connection box and it is just standard 12g 3 wire coming from the gen and going to the power block.

I want to upgrade this so I can run the 2nd AC on shore power (50 amp) without removing the straight 30 amp internal front back switch from the loop as that would limit functionality. Adding the 110v transfer switch is a bonus and should be really easy once I get this issue figured out.

Thanks for the help in advance.

[BFlinn181]

50 amp service for an RV is actually 2 hot leads of 120v 50 amps each, 180º out of phase. Both Hots tie into the one neutral line. The 180º out of phase never allows 240v to be 'seen' by the neutral wire. This is actually 100 amps of power available to the RV in two separate 'legs' of 50 amps each. 120v X 100 amps =12,000 watts.

In a 30 amp RV, one hot and one neutral for up to 30 amps. 120v X 30 amps = 3,600 watts, or a little more than 1/3 the capacity of 100 amp service.

In your RV, the generator has two circuits, one tied into the transfer switch and provides power all the RV except the 2nd A/C. The second A/C is wired directly to the other circuit of the generator. Shore power can only provide power to the 30 amp service through the transfer switch.

You could replace your 30 amp shore cord with a 50 amp cord, only wiring one side to the transfer switch. The other side of the 50 amp cord could be wired to a female 30 amp outlet in the electrical bay. The wiring from the generator that goes to the 2nd A/C could be terminated with a second 30 amp female outlet in the electrical bay. Using the end of the ond 30 amp shore cord wired to the A/C unit, if you plug it in to the shore outlet, it gets powered by the 50 amp shore cord. Plugged in the other outlet, the generator would provide the power as it does now.

No new transfer switch needed, very simple solution to your wiring problem. The present 30 amp master breaker in your breaker panel limits you to 30 amps, even though the pedestal could provide up to 50 amps. The second circuit provides more than enough power to the A/C unit.

You may wish to install a circuit breaker in the circuit to protect the A/C unit since it wouldn't be protected except by the 50 amp breaker in the pedestal.

[imob]

Thanks for the input and I going to have to reread that in the morning to fully digest it. That is exactly the help I needed.

As for the transfer switch the reason is that it is literally currently a direct plug. The gen goes to an an outlet. The shore line powers the house. It is ether plugged into the gen or the post. Moving from one to the other requires shutting everything down, transfer and bring everything back up. Though for the AV gear I am putting in a 12v/110 inverter with a built in transfer switch non-charging.

https://www.amazon.com/dp/B00TI1D5JK...I2A337328V5EGI

The AV area was pre-wired with 12v leads for one so it is a 1,2,3 install.

[imob]

Originally Posted by BFlinn181

50 amp service for an RV is actually 2 hot leads of 120v 50 amps each, 180º out of phase. Both Hots tie into the one neutral line. The 180º out of phase never allows 240v to be 'seen' by the neutral wire. This is actually 100 amps of power available to the RV in two separate 'legs' of 50 amps each. 120v X 100 amps =12,000 watts.

In a 30 amp RV, one hot and one neutral for up to 30 amps. 120v X 30 amps = 3,600 watts, or a little more than 1/3 the capacity of 100 amp service.

In your RV, the generator has two circuits, one tied into the transfer switch and provides power all the RV except the 2nd A/C. The second A/C is wired directly to the other circuit of the generator. Shore power can only provide power to the 30 amp service through the transfer switch.

You could replace your 30 amp shore cord with a 50 amp cord, only wiring one side to the transfer switch. The other side of the 50 amp cord could be wired to a female 30 amp outlet in the electrical bay. The wiring from the generator that goes to the 2nd A/C could be terminated with a second 30 amp female outlet in the electrical bay. Using the end of the ond 30 amp shore cord wired to the A/C unit, if you plug it in to the shore outlet, it gets powered by the 50 amp shore cord. Plugged in the other outlet, the generator would provide the power as it does now.

No new transfer switch needed, very simple solution to your wiring problem. The present 30 amp master breaker in your breaker panel limits you to 30 amps, even though the pedestal could provide up to 50 amps. The second circuit provides more than enough power to the A/C unit.

You may wish to install a circuit breaker in the circuit to protect the A/C unit since it wouldn't be protected except by the 50 amp breaker in the pedestal.

You are 100% correct! I just went out and fired the gen without the shore line plugged in and the back AC turned on. Now things make much more sense.

So If I get a 50amp transfer switch and cord I should wire black to the house and red to the AC with accompanying gen leads to match. Tie off the neutral and ground through the switch and should be good to go.
I do like the idea of the 30amp breaker for the AC shore lead.

Does that sound right?

[mhbell]

Here is a link to how I converted mine. When using the generator Only one AC (Front one) will work. When on shore power both will work and I did not change the transfer switch.
Mel

Link Click Here

[imob]

This is what I see as a wiring diagram

* Note - Yes I just noticed I tied the white on Gen lead 2 to the ground instead of the common... -10 points

In his article he did not want to add an ATS. I understand you can wire around it but as it is only $170 I think it is worth it.

https://www.amazon.com/dp/B00153EYU8...I2AM5XXZMCNXNX

[jcgribks]

Here's how I converted my 1996 Itasca Suncruiser with 30amp over to 50 amp. from an earlier post.

http://www.irv2.com/forums/f84/secon...ml#post1509385

There's also a link to a pdf showing how I wired it.

[imob]

Thanks for the share jcgribks. A few things I am trying to understand:

1. Why is there still an internal plug/outlet between the 70a breaker box and the Control center? What purpose does it serve?

2. Did the Control center not already have a main 30a breaker?

3. In this diagram they took out the Dual Air Switch out of loop there by limiting use if for some reason you only have 30a shore service... correct?

BTW the factory diagram is how mine is wired as well.

[BFlinn181]

To do as you suggest means buying a new 50 amp ATS, a new shore cord, and probably a new 50 amp breaker panel. To take full advantage of the 50 amp service would require re-wiring the RV, a very difficult proposition in one that's already built.

If you just do as I suggested, put a 'break' in the circuit from the generator to the rear A/C and install a 30 amp plug and outlet. (Outlet on the generator side) Then wire the new 50 amp shore cord, one hot to the ATS, the second hot to another 30 amp outlet, you now have a 'manual' transfer switch by how you connect the plug from the rear A/C. In one outlet, it's powered by the generator, in the other outlet it's powered by the new 50 amp shore cord. No new ATS needed, the old 30 amp shore cord can be used to provide the short cord and plug from the rear A/C. A much cheaper, faster solution to your needs.

I was having problems with my drawing program, I guess it's not quite ready for the latest Mac OS. Here's what I suggest:

[BFlinn181]

I just reread post #3, I NOW see that you don't presently have a transfer switch. You could install one for $100-200, or just upgrade your system this way:

The 2nd line from the generator that is now connected to the rear A/C is connected to the 50 amp generator outlet. The rear A/C is wired into the new breaker and the 50 amp plug that you plug in to select power source.

[imob]

Originally Posted by BFlinn181

To do as you suggest means buying a new 50 amp ATS, a new shore cord, and probably a new 50 amp breaker panel. To take full advantage of the 50 amp service would require re-wiring the RV, a very difficult proposition in one that's already built.

Why would I need a new panel? Amperage is calculation of load. I am not increasing the load on the main panel and the 30 amp main breaker on the existing panel would prevent anything greater. Remember that when a supply device says 50 amp that means it is capable of delivering that amount not that it does. If the gen is running and nothing is plugged into it, it is pushing 0 amps though it is capable of delivering 45 amps. As my downstream load is restricted to 30 amps it should be fine. Now yes I am leaving 20 amps of capacity not being used but as you said that would require a re-wire of the rig, and there is no need for that.

As for the transfer switch and cord yes that is the upgrade. That way I can pull up with the gen running and hook up without having to shut everything down when its 98 degrees outside.

I am expecting this project to cost $300. $171 for the ATS, $99 for a 36' 50a cord and a few dollars for a breaker box for the red wire.

[BFlinn181]

You don't need a new power panel, I just thought if you were upgrading to 50 amps and installing a 50 amp ATS you might want to use the 70 amps your present panel can't handle on the 50 amp service.

My post #10 shows you don't need to install an ATS. I was trying to do it with minimum cost. I have an ATS and don't really see the need, two outlets and a short 50 amp cord connected to my breaker box would do the job. Leaving it normally plugged into the generator outlet except when I'm connecting to shore power wouldn't me a chore for me, I have to get the cord from the compartment anyway. That compartment also contains my Progressive Ind. EMS that I always observe for a couple of minutes to make sure the pedestal is providing correct power.

[imob]

I do see your point. My main reason for the ATS is that I found this summer... when it was a heat index of 116 for 13 hours of the day and only 1 AC running the rig got very hot very fast during setup and took forever to cool off again. And since I already had to mess with the wiring, why not put it in.

I do like the power check idea. I might add that to my setup steps.

[jcgribks]

I think the outlet you're asking about is the 50amp that I show. My 50 amp cord is not hard wired. I have male plugs on both ends. I just have to be careful to plug into the outlet on the motorhome 1st and then the shore power.

My rig didn't have any sort of ATS. Of the 2 outlets on the generator, the 30 amp supplied the motorhome and the 20 amp the rear AC. But the problem was a previous owner removed the front/rear AC switch and wired them together.

I still have the factory 30amp hard wired cord. The generator 30 amp power just dead ends at an outlet. My 30 amp cord ether plugs into this or unplug it and plug into shore power.

The reason I wired it up the way I did with a separate 70 amp breaker Box and a ATS is I wanted 1 cord to plug into shore power. I could have done it cheaper but I didn't want to have to plug in my 30 amp cord and then a separate 20amp cord on shore power to have the rear air on.