New Monty gen install

[Tonet57]

Originally Posted by Dusters

As stated by others, I also have a 5500 Onan Propane genset that was installed at time of pick-up for 2016 Monty. The wiring and genset was nearly $8K more for our purchase. Was it worth it, I can't say for sure. The advantage so far was jump starting the generator, so I could use my leveling system when the batteries were pretty weak from sitting. The Con is mostly losing significant storage space in front and weight.

I just recently bought a new 381th that was presided for generator I paid to have a 5500 onanistic installed when I got it home and tried it out everything was great till I turned on second air conditioner I threw a breaker I called the dealership about it and was told can only run generator at a time because it was only prewired for 30 amp why in the world would a 50 amp unit only be prewired for 30 amp and why even put a 5500 in it waiting on keystone reply about this probably won’t get anything done about it because it is prewired was wondering if anyone else has had this problem or if my dealer is just blowing smoke you know where

[Tonet57]

Just bought a 2020 381th that was pre wired for generator had a 5500 onanistic installed brought it home and turned on generator and air conditioner everything was fine turned on second air and threw a breaker called dealer and was told it was only pre wired for 30 amp why in the world would a 50 amp unit be pre wired for generator 30 amp and why put in a 5500 any one else experience this still waiting on keystone for a reply

[mhs4771]

There seems to be two models of 5500 Onans, one has dual 30 Breakers and the other has one 30 and one 20 amp breakers.
Which do you have?? We have the dual 30s and can and have run both 15K ACs numerous times.

[Tonet57]

Originally Posted by mhs4771

There seems to be two models of 5500 Onans, one has dual 30 Breakers and the other has one 30 and one 20 amp breakers.
Which do you have?? We have the dual 30s and can and have run both 15K ACs numerous times.

I have the one with a 30 and 20 do you know if you were pre wired

[Renegade1LI]

You can only use a 5500 as the wiring for the generator is only 10ga, which means 30 amps max. I have the same camper & was a little disappointed when I realized it. I am installing a 10k diesel generator in the truck bed & will wire it up tp plug the camper into at the bumper.

[Tonet57]

Originally Posted by Renegade1LI

You can only use a 5500 as the wiring for the generator is only 10ga, which means 30 amps max. I have the same camper & was a little disappointed when I realized it. I am installing a 10k diesel generator in the truck bed & will wire it up tp plug the camper into at the bumper.

I got a hold of keystone and they told me it should be able to take 50 amp checked in junction box and there is 4 wire for 50 told my dealer what they said and he said well it can be done but we’ll have to make some changes I told him I don’t care what he has to do but I want 50 amp going to take it back in end of month after I take a small road trip see what else maybe wrong let you know what happens it appears to me that they wired it to the 20 amp breaker instead of the 30 amp breaker for the air because the 20 breaker is the only one going off

[mhs4771]

Just to confirm, our Onan is an OEM install as we custom ordered our unit to get exactly what we wanted.

[jetskier]

The Onan 5500 generators have 4 wires and a ground. There's a black, black-green stripe, two whites and ground. The black is on the primary 30A breaker and the black-green is the secondary hot (usually 20A). Each white neutral is paired with one of the hots. Additionally, both blacks are in-phase with each other (aka you can't get 240V by probing up the two hots with a multimeter)

If you have generator prep, there should be a 50A transfer switch in the "basement dungeon of wires and pipes" under the bathroom and a junction box mounted to the ceiling of the front pass-through storage. When I wired my 5500 in from my old trailer, the junction box had a 10-4 romex w/ ground that ran to the transfer switch. This matched up with the 4-wire and ground from the generator. If you open up the junction box, you can switch the two hots there and see if it works better. There may be too many circuits beside the 2nd AC feed by the 20A generator breaker at the main panel (other outlets, water heater, etc).


Mine had the 20A secondary. I ordered a 30A secondary to replace it. the 20A is usually exclusive of a 2nd AC only and nothing else on that generator circuit. It's hard to isolate on a 50A system.

[Renegade1LI]

Originally Posted by Tonet57

I got a hold of keystone and they told me it should be able to take 50 amp checked in junction box and there is 4 wire for 50 told my dealer what they said and he said well it can be done but we’ll have to make some changes I told him I don’t care what he has to do but I want 50 amp going to take it back in end of month after I take a small road trip see what else maybe wrong let you know what happens it appears to me that they wired it to the 20 amp breaker instead of the 30 amp breaker for the air because the 20 breaker is the only one going off

Ours has a 30 amp transfer switch with 10ga wire, if you want 50 amps you will have to install 6 GA wire. The wiring from the generator to the switch has to be 6 ga, as well as the wiring from the switch to the main breaker. Do not run 50 amps through 10 ga wire, make sure the installer changes everything to be rated 50 amp. The transfer switch is located behind the electrical panel if you want to check it.

[Renegade1LI]

See pic of factory installed wiring,30amps max.

[jetskier]

Originally Posted by Renegade1LI

Ours has a 30 amp transfer switch with 10ga wire, if you want 50 amps you will have to install 6 GA wire. The wiring from the generator to the switch has to be 6 ga, as well as the wiring from the switch to the main breaker. Do not run 50 amps through 10 ga wire, make sure the installer changes everything to be rated 50 amp. The transfer switch is located behind the electrical panel if you want to check it.

10 GA is fine from the generator whether you have a 30A or 50A transfer switch.

[Renegade1LI]

Originally Posted by jetskier

10 GA is fine from the generator whether you have a 30A or 50A transfer switch.

Not sure why you think it's ok, it's against national electric code.

[jetskier]

Because the two generator circuits do not exceed 30A. The shorepower feeds to the inputs and output feeds of the 50A transfer switch are 6ga, but the generator inputs are only 10ga.

[Renegade1LI]

Originally Posted by jetskier

Because the generator circuits do not exceed 30A. The shorepower feeds to a 50A are 6ga into and out of the transfer switch.

It's very simple, wire size is based on the highest potential of the system, if you have a50 amp breaker that's what the wire is based on. If the op is installing a50 amp generator he needs 6ga wire.

[jetskier]

Originally Posted by Renegade1LI

It's very simple, wire size is based on the highest potential of the system, if you have a50 amp breaker that's what the wire is based on. If the op is installing a50 amp generator he needs 6ga wire.

He's not installing a 50A generator. Read the first post. 5500W Onan. It comes with a 30A primary and a 20A second breaker.

[Renegade1LI]

Originally Posted by jetskier

He's not installing a 50A generator. Read the first post. 5500W Onan. It comes with a 30A primary and a 20A second breaker.

Just so you know a 5500 watt generator at 120 volts is 45.8 amps, which would require a 50 amp breaker with 6 ga wire, 5500 watts divided by 120 votls =45.6amps

[jetskier]

Originally Posted by Renegade1LI

Just so you know a 5500 watt generator at 120 volts is 45.8 amps, which would require a 50 amp breaker with 6 ga wire, 5500 watts divided by 120 votls =45.6amps

I know what the 5500W Onan outputs. Clearly, you've never owned one and wired one up. Yes, it does have the capability to output 45.8amps TOTAL. However, it has two breakers that limit the current output to 30A and 20A and the Onan wiring harness is wired with 10ga off those two breakers. Each of those two breakers feeds the ATS with its own 10gauge hot and its own 10ga neutral. They are in-phase so they don't share the neutral. There is no need for a 6ga wire for 30A circuit. You are interpreting the situation wrong. Keystone and every other RV manufacturer out there must be in the wrong as well because they wired the junction box to the 50A ATS with 10-4 Romex w/ ground. NOT 6 GAUGE.

[Renegade1LI]

Originally Posted by jetskier

I know what the 5500W Onan outputs. Clearly, you've never owned one and wired one up. Yes, it does have the capability to output 45.8amps TOTAL. However, it has two breakers that limit the current output to 30A and 20A and the Onan wiring harness is wired with 10ga off those two breakers. Each of those two breakers feeds the ATS with its own 10gauge hot and its own 10ga neutral. They are in-phase so they don't share the neutral. There is no need for a 6ga wire for 30A circuit. You are interpreting the situation wrong. Keystone and every other RV manufacturer out there must be in the wrong as well because they wired the junction box to the 50A ATS with 10-4 Romex w/ ground. NOT 6 GAUGE.

I think we are talking about two different issues the op's trailer is the same as mine a 381 which came with a 30 amp transfer switch & is wired from the gen set with 10ga wire. I agree the two generator inputs, 20 & 30 amps can be 10ga with separate neutrals with a 50 amp transfer switch, also I saw a wiring diagram for a 30 amp transfer switch wired to the 30amp breaker & 20amp going to the rear ac not through the transfer switch, what the op has.It seems keystone & every other manufacturer picked the cheapest way using a 30amp switch & direct wiring the second ac. Personally I am going to change the transfer switch to 50amps so there would be more power available if not running the second ac. See attached pic of the mess they installed which I assume is whats in the op's.

[mhs4771]

Folks lets take a step back, I don't care what the generator is, but if the main shore power is 50 amps (50 on each leg) then that's the wrong Transfer Switch. Unless that unit is wired different than normal. Both Shore power and Generator power go into the Transfer Switch with ONE output line. The whole purpose of the Switch is to switch between Shore and Generator power with normally Generator being the primary.

[JamesD]

Ugh... dealer installs.
My RV was supposed to have an inverter for the residential fridge.
It must have been optional, because the writing on the breaker box for the inverter was penciled in, and instead of an inverter, they installed a 2nd converter charger, and the fridge was wired direct to the breaker box. No way there had ever been an inverter.
The original owners clearly didn't understand they had been ripped off.