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Old 11-24-2017, 10:11 PM   #1
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M.O.C. #20852
Generator Circuit Box Puzzles Me @ 30 Amp Max

My 2017 Keystone High Country 358BH came gen prep'd, and I'm installing a Cummins Onan 6.5HGJAB-904J LPG Generator Set.

I found the Generator Circuit box in the pass-through storage ceiling (I think more commonly referred to as the basement?). But it has me scratching my head right off the bat because it says 30 amps max but the trailer is 50 amps.

Does anybody have any insight on this? I'm wondering what gives concerning the 30 amps max in that circuit box? I was expecting it to indicate 50 amps max.

Maybe somebody with an Onan in their trailer can open their gen box cover and take a look how the wires are connected? That would be awesome! Thanks in advance.


EDIT:

OK - I took another look at the schematic, and I figured out a couple things >>

From Onan:
Green goes to ground (actually knew that already)
Whites twist together onto white/blue pair in box (guessing blue wire is L2 neutral in 50 amp circuit)

Black & Black w/Yellow stripe must be L1 & L2 in 50 amp circuit (shore power).

Since there is only one pair remaining, I imagine they connect to the Black/Red in the box. But I'm not sure if they twist all 4 together, or if I should separate the Black & Red and connect the Black from Onan to Black in Gen Circuit box and Black/Yellow Stripe from Onan to Red in Gen Circuit Box.

So that's my new question. Thanks.
Attached Images
File Type: gif GenBoxCover.gif (127.7 KB, 1 views)
File Type: gif GenBoxWires.gif (89.1 KB, 4 views)
File Type: gif OnanOutputs.gif (134.1 KB, 1 views)
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Old 11-24-2017, 11:21 PM   #2
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I don't know about your Onan 6500, but my 5500 has a 30A breaker on each output leg.

A 5.5kw generator would max at 46A (5500W/120V), or 23A on each leg; so the 30A breakers are sufficient. A 6.5K generator would max at 54A, or 27A on each leg; it will probably also have 30A breakers

In case you are wondering about the ability of your generator vs shore power:

50A Shore power
2 legs @ 50A each provide 12kw to the trailer (50x120x2)

Generator
2 legs @30A each could provide 7.2kw to the trailer (30x120x2), but my generator is limited to 5.5kw. Yours will be 6.5kw.

30A Shore power (not a Montana)
1 leg @ 30A provides 3.6kw to the trailer.

Bottom line; a 5.5KW provides about half the power that the 50A shore connection provides but a lot more than a trailer with 30A shore power. I have run both AC units with my generator, but can't remember running the microwave at the same time; it probably would not handle that.

As for your wiring question: you only need four wires. Hot 1, Hot 2, Neutral, Ground.

Here is a picture of my generator junction box and the transfer switch wiring schematic.
Attached Images
File Type: jpg Generator Junction Box 3 -2.jpg (1.77 MB, 1 views)
File Type: jpg Generator Transfer Sw 1 -2.jpg (1.02 MB, 0 views)
File Type: jpg Generator Transfer Sw 4 -2.jpg (1.24 MB, 2 views)
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Old 11-24-2017, 11:59 PM   #3
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Ref your edit:

Looking at both of our photos, I'm a little confused. Looks like there are more wires going leaving the junction box than there are arriving at the transfer switch!

This is how I think it should be wired at the transfer switch:

White = neutral leg 1
Blue = neutral leg 2
Black = Hot leg 1
Org = Hot leg 2
Bare copper = ground

I did not separate all the wiring in the junction box, so the photo is a little confusing. My trailer is at the dealer for service and I won't be able to verify the connections in the junction box for a week or two.

Of course this is no guarantee they used the same cabling in our units; probably did, but not a 100% guarantee. Your colors might be different.

Be very careful, you are dealing with high voltage. Don't fire (maybe literally) anything up until you are absolutely sure. I can do some more checking but not till I get my unit back.
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Old 11-25-2017, 12:06 AM   #4
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Holy cow Scott! Thank you so much for that information. Totally great job at explaining that in an easily understandable way. The sales guys told me that this generator would run everything in my trailer and both trailers next to me, and I was wondering about that; it sounded too good to be true.

And yes, 4 wires does make sense; L1, L2, N and G.

And seeing your transfer switch gives me the answer I'm looking for. I need to split the Black & Red wires in that wire nut and connect them to the Black & Black/Yellow Stripe respectively. I also see that you have the exact same orange sheath ?10 AWG? that I have in my trailer so we are wired the same.

Also, seeing your transfer switch kinda makes me feel like I dropped the ball because in hind-sight I could have just found mine and looked at it. But I honestly didn't think of doing that until after I just saw yours; I'm really not lazy. LOL...

Thanks again for the help. I really appreciate the pictures and the time you spent to take them and upload them.


Edit:
I added the Onan Schematic that is in the manual that I referenced in my edit from above.
Attached Images
File Type: png OnanSchematic.PNG (38.4 KB, 2 views)
File Type: png OnanLegend.PNG (10.3 KB, 0 views)
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Old 11-25-2017, 12:25 AM   #5
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Quote:
Originally Posted by scottz View Post
Ref your edit:

Looking at both of our photos, I'm a little confused. Looks like there are more wires going leaving the junction box than there are arriving at the transfer switch!

This is how I think it should be wired at the transfer switch:

White = neutral leg 1
Blue = neutral leg 2
Black = Hot leg 1
Org = Hot leg 2
Bare copper = ground

I did not separate all the wiring in the junction box, so the photo is a little confusing. My trailer is at the dealer for service and I won't be able to verify the connections in the junction box for a week or two.

Of course this is no guarantee they used the same cabling in our units; probably did, but not a 100% guarantee. Your colors might be different.

Be very careful, you are dealing with high voltage. Don't fire (maybe literally) anything up until you are absolutely sure. I can do some more checking but not till I get my unit back.


Yep. I totally agree with the way you think the wiring should be here.
From the Onan I will:
Take both White wires and get an extra large nut to wire it together with the White/Blue pair in that box.
Take the Black & Black w/Yellow Stripe and wire them respectively with each of the Black & Red in that one pair from my picture.
Take the Green and wire it to the Bare & Black wires that are twisted together in that box.

It's odd that there is a Black wire twisted to that Bare wire though. Makes me wonder what the heck they did that for. Perhaps I should play it safe and drag the trailer down to the dealer before I fire up the generator to have them take a quick look. Not sure if they will, but it's worth a shot. Or maybe I'll see if I can contact a Montana Keystone technician and ask them.

Or... Better yet... Perhaps I'll just trace that wire back to the transfer box and see where it connects and figure it out for myself. I should be able to figure it out based on the schematics. Last thing I want to do is fry my brand new RV.
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Old 11-25-2017, 12:46 AM   #6
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Sitting here thinking about it, I think I know what the extra wiring is for. There will be a Hot 1, Hot 2, Neutral (probably two of them) going the the transfer switch. There will also be lead(s) (I don't want to say what colors since I can't verify at this point) that will be connected to the hot lead(s) in the junction box and are used to control the transfer switch (I think I see them behind the L1/L2/N leads in the transfer switch). When the generator starts, the voltage on this extra lead is what makes the transfer switch move to the generator position.
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Old 11-25-2017, 12:47 AM   #7
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That Black wire twisted to that Bare Ground wire in that Generator Circuit box picture was killing me so I went outside and took another look at it. It's just a pig-tail grounding that metal box. So I should be golden as far as the Onan outputs go. Thanks again for the help.
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Old 11-25-2017, 12:49 AM   #8
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Glad to help and that I had those photos on file.
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Old 11-25-2017, 12:58 AM   #9
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Quote:
Originally Posted by scottz View Post
Sitting here thinking about it, I think I know what the extra wiring is for. There will be a Hot 1, Hot 2, Neutral (probably two of them) going the the transfer switch. There will also be lead(s) (I don't want to say what colors since I can't verify at this point) that will be connected to the hot lead(s) in the junction box and are used to control the transfer switch (I think I see them behind the L1/L2/N leads in the transfer switch). When the generator starts, the voltage on this extra lead is what makes the transfer switch move to the generator position.


OK... But I think any other wires should already be connected at the factory right? Check the Onan schematic that I added above. That schematic shows the 5 Onan outputs that have to be connected, and I'm sure they all go to that Generator Circuit Box. Note that there is no #10 and above because that is for 30A trailers.

I know there is that other push type connector in the "tin house", and that has a few wires in it. But that just needs to be pushed together to get that handled. And that goes up to the start/stop/hours switch at the control panel. If anything in there traces back to the transfer switch I'm sure it's already connected up by the factory since mine came gen prep'd.


Edit:

Where is your transfer switch physically located? I'm wondering where mine is and maybe it's in the same place yours is in. I could at least start by looking in the same place where yours is at I guess? What do you think?
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Old 11-25-2017, 01:23 AM   #10
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Yes, I think the control wires were probably connected by the factory.

My transfer switch is behind a panel on the left as you open the right side basement door.
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