Any gotchas converting to 50 amp 110 volt?

[belfert]

Powertech recommends running my particular generator 110 volt only if no 220 is required.

What gotchas are there in using only one leg on a 50 amp receptacle?  I believe I have enough power to run both A/Cs, fridge, and water heater on 50 amps, but I have to do a bit more research.  When on generator I will have plenty of power for sure.

Will my IOTA 50 amp transfer switch still work with only one leg active?

[JackConrad]

   Let me try to explain how we wired our bus.  Our load center main breaker has 2 Hot terminals.(one from each leg of a 50 amp power supply (shoreline). The terminals are fed from the 2 hot output terminals of our transfer switch (along with the neutral & ground). The transfer switch has 2 hot terminals (and a neutral & ground) for each power supply coming into the coach. The shoreline terminals are connected to the 4 wires from our shoreline (2 hot, neutral, & ground). Since our generator is 120 volt only, it only has 3 wires (1 hot, neutral, & ground). These wires are connected to the generator input terminals in the transfer switch. a jumper wire (6 gauge) is added between the 2 hot generator terminals in the transfer switch.
   This gives us full 50 amp capability when plugged into a 50 amp shoreline connection. When plugged into a 30 or 20 amp shoreline (using an appropriate adapter, the adapter splits the 20 or 30 amp single hot wire and feeds it to both legs of the 50 amp 4 wire cable.  Of course, you are always limited to the total amps available (20, 30 or 50). 
    This is just our way, there are several other ways of doing this. Perhaps others will give give some other options.  Jack

[Blacksheep]

Uhh this is we did ours!

Our load center main breaker has 2 Hot terminals.(one from each leg of a 50 amp power supply (shoreline). The terminals are fed from the 2 hot output terminals of our transfer switch (along with the neutral & ground). The transfer switch has 2 hot terminals (and a neutral & ground) for each power supply coming into the coach. The shoreline terminals are connected to the 4 wires from our shoreline (2 hot, neutral, & ground). Since our generator is 120 volt only, it only has 3 wires (1 hot, neutral, & ground). These wires are connected to the generator input terminals in the transfer switch. a jumper wire (6 gauge) is added between the 2 hot generator terminals in the transfer switch.   This gives us full 50 amp capability when plugged into a 50 amp shoreline connection. When plugged into a 30 or 20 amp shoreline (using an appropriate adapter, the adapter splits the 20 or 30 amp single hot wire and feeds it to both legs of the 50 amp 4 wire cable.  Of course, you are always limited to the total amps available (20, 30 or 50). 

Sound just like Jacks! It should! He did it! LOL

Ace

[Nick Badame Refrig/ACC]

Hi Brian,

I'm not sure which model Ioto switch you have but the contactors in my switch are 230v which is only engaged

when the generator is used. It will default to land line/inverter when no gen. power is presant.

Good Luck
Nick-

[JackConrad]

Hi Brian,
I'm not sure which model Ioto switch you have but the contactors in my switch are 230v which is only engaged when the generator is used. It will default to land line/inverter when no gen. power is presant.
Good Luck
Nick-

That is probably the same switch we have.  Although the contators handle 240 volt, it only takes 120 volt from our generator to activate the contactors. Also note there is a time delay on the generator, so the contactors do not switch as soon as the generator starts. Probably 30-50 second delay.  Jack

[Jerry Liebler]

Belfert,
     If you switch your generator to 120 only, you'll need to be sure you have adequete wire size on all conductors.  If your generator is 7.5kw or less a single 6 AWG is fine BUT! if your generator is 12 or 15 KW  you'll need 2 ea. 6awg conductors for each the hot and neutral.  That's 2 hots AND 2 Neutrals from the generator to the transfer switch and from the transfer switch to the breaker panel.  If  it is now wired for a 240 volt generator of over 7.5kw you'll need to add another 6 AWG from the transfer switch to the breaker panel if you change to 120 only.  Usually a 10kw generator would be wired for 120 only but a 12kw or 15kw would be best run as 120/240.
Regards
Jerry 4107 1120

[Paul]

On 50amp RV receptacles, you will have 50 amps of 240 volts or 100 amps of 120 volts. 50 amps at 120 volts on each side of the line for a total of 100amp at 120volts.

From an 8 KW generator wired for 240 volts would have 33 amps of 240 volts or 33 amps of 120 volts on each side of the line for a total of 66 amps. This would run one roof top AC on each side of the line with 20 amp breakers each line.

From an 8KW generator wired for 120 volts you have 66 amps of 120 volts. This would run three roof top AC on 20amp breakers. This is why you want to wire it for 120 volts.

Hope this helps,
Paul

[belfert]

I know from experience that you can run two A/Cs from a 30 amp circuit.  Just be sure to turn off the battery charger in the inverter.  I bought the most power thrifty rooftops I could find.

It looks like no reason not to do this change.  The hardest part will be changing the generator and running bigger cable to the generator.

[TomC]

I have a very simple electrical system.  My 10kw Powertech is wired straight 120vac.  It goes through two 50 amp circuit breakers that are bridged together-then the power goes to the main circuit breaker box.  When I want shore power, I turn the generator circuit breakers off, slide my fail proof switch slider over and then turn on only one leg of the 50 amp land line.  Since only my furnace and stove are propane, we have everything else electric.  With some simple timing and not turning on everything at once, 50 amp has been enough power-so much so that on my next conversion, I am going to wire it exactly the same way.  Automatic transfer switches, or anything automatic, makes me nervous.  I prefer manual switch over.  Good Luck, TomC

[gumpy]

I guess I don't understand the original question. 

The generator is wired for 240v.  There should be 2 hot wires, a neutral, and a ground coming out of it. 
You have a transfer switch which switches 2 hots and a neutral for two separate power sources (shore and generator).
You have a load center with 2 legs in it (240v).
You have an inverter which produces a single hot leg. Somehow you have this wired into the load center. I assume your inverter has a transfer switch and you pass one side of the transfer switch output through it to power one leg of the load center.

What I don't see is how you power the second leg of the load center.

Why not just leave the generator set to 240v adn power the second bus in the load center off the second leg of the transfer switch output?  One 240V leg goes to the inverter and through it's internal transfer switch to one side of the load center, and the other 240v leg goes direct to the other side of the load center. When on a 120v shore power, you use a dogbone which crosses the hot line to the second leg internally. The only time you'd have an issue with one side of the load center not being powered is when strictly on inverter, and there are ways to get around that easily.

What I did for this was to set up my transfer switch (home built, not IOTA) to cross the inverter output to the second bus in the load center under normal conditions. When 240v is applied to the transfer switch, it breaks that crossover, and one leg of the 240v is sent to the inverter while the second leg powers the second bus in the load center.

Works well for me.

[belfert]

My generator is currently set for 240 volt and came that way.  The generator manufacturer highly recommends changing over to 120 volt only unless 240 volt is required.  The generator will not be able to maintain proper voltage if the load is unbalanced on the two 120 volts leads in 240 volt mode.

I was originally thinking about only using one 50 amp leg of the power cable, but Jack and Ace have an easy answer for using both legs when on shore power.

[JackConrad]

My generator is currently set for 240 volt and came that way.  The generator manufacturer highly recommends changing over to 120 volt only unless 240 volt is required.  The generator will not be able to maintain proper voltage if the load is unbalanced on the two 120 volts leads in 240 volt mode.
I was originally thinking about only using one 50 amp leg of the power cable, but Jack and Ace have an easy answer for using both legs when on shore power.

That is what  PowerTech told us also.  They said the voltage regulator monitors 1 of the 120 volt output legs when the generator is wired for 120/240 volt. If the monitored leg has a high load, the voltage regulator responds and other leg with little load will have a higher voltage.  If monitored leg has little or no load, it will not sense a high load on the other leg.  We were told if wired 120/240, you should maintain loads on the 2 legs within 20% to prevent damage from to the the windings.  Jack

[belfert]

     If you switch your generator to 120 only, you'll need to be sure you have adequete wire size on all conductors.  If your generator is 7.5kw or less a single 6 AWG is fine BUT! if your generator is 12 or 15 KW  you'll need 2 ea. 6awg conductors for each the hot and neutral.  That's 2 hots AND 2 Neutrals from the generator to the transfer switch and

The ampacity for 6 AWG wire is 65 amps and my 8KW generator can do 66 amps at max.  It would seem to me I could use a single 6 AWG wire and be fine since it is highly unlikely I would ever go above 65 amps.

Powertech is recommending running both 6 AWG wires to the transfer switch and then combining them down the line.  I don't quite understand how this all works as there is a 35 amp breaker on each leg now.

[gumpy]

That's 66 amps total for both legs. 33 amps per leg.

[Nick Badame Refrig/ACC]

Hi Brian,

I have line monitors on both legs of my Onan 12.5kw wired for 220v and weather the load is unbalanced or not,

it will always be within 112 to 122 volts. Usually always at 117 volts on each.

I have seen many parks with unbalanced legs comming into my coach and thats where problems start.

Nick-