Roadtrek RS Adventurous Inverter Upgrade

[engnrsrule]

Thanks Booster. The measurements while on inverter were with shore tie unplugged. The 2 transfer switches are Hot and Neutral. The old Tripplite charger/inverter had 120v pass through. The new arrangement separates the functions and the added ABT replaces the switching - pass thru function in the Tripplite.

[booster]

Originally Posted by engnrsrule

Thanks Booster. The measurements while on inverter were with shore tie unplugged. The 2 transfer switches are Hot and Neutral. The old Tripplite charger/inverter had 120v pass through. The new arrangement separates the functions and the added ABT replaces the switching - pass thru function in the Tripplite.

I had thought you had mentioned the first being a hot only, but I see it was in regards to priority not what wires were switched.

[engnrsrule]

My first iteration had planned to use a single pole relay to manage the new inverter, but that was before you enlightened me! I also considered one on the new charger's feed, but that was not needed when I fed it from ABT 1, since that supply is dead when shore tie and generator power are absent.

[Road Toad]

Originally Posted by engnrsrule

My first iteration had planned to use a single pole relay to manage the new inverter, but that was before you enlightened me! I also considered one on the new charger's feed, but that was not needed when I fed it from ABT 1, since that supply is dead when shore tie and generator power are absent.

This was our choice for ABT. It worked out well.
https://www.amazon.com/Go-Power-TS-3...%2C209&sr=8-10

[booster]

For curiosity, I just did a quick search for 3 input automatic transfer switches.


I actually found one this time, albeit a 50 amp and quite expensive one.


https://rvpartsexpress.com/product/a...sources-es350/


It does have some interesting things said about, though. It is generator first priority which surprised me a bit but in real life if the delay switch it doesn't matter anyway, I think.


Of more interest was that it allows for automatic load shedding when the inverter is on if you add a second breaker box to isolate what loads you want of on inverter. This would be similar to what the do with home generator emergency sets, but only for inverter in an RV. Shedding power would be an absolute necessity in big rigs with3 AC units and lots of other things running all the time. This is basically like Roadtrek did with the separate inverter outlet setups they made but the secondary breaker box was the inverter itself and only one circuit, with everything else shed.

[engnrsrule]

Roadtoad and Booster...

I saw the $79 one and its fine but due to space consideration I got this one that has a smaller footprint.
https://www.amazon.com/dp/B00F84S3KM.

A three pole option I saw was a 50 amp model with the requisite small footprint for $186. It would require two to ensure full isolation across the system. However my concern is whether I would be compromising safety by not connecting the grounding bus. In a 50a system there are 4 wires - 2 hots, 1 neutral and ground, and such installation would employ the shared ground bus.

[Road Toad]

Originally Posted by booster

For curiosity, I just did a quick search for 3 input automatic transfer switches.


I actually found one this time, albeit a 50 amp and quite expensive one.


https://rvpartsexpress.com/product/a...sources-es350/


It does have some interesting things said about, though. It is generator first priority which surprised me a bit but in real life if the delay switch it doesn't matter anyway, I think.


Of more interest was that it allows for automatic load shedding when the inverter is on if you add a second breaker box to isolate what loads you want of on inverter. This would be similar to what the do with home generator emergency sets, but only for inverter in an RV. Shedding power would be an absolute necessity in big rigs with3 AC units and lots of other things running all the time. This is basically like Roadtrek did with the separate inverter outlet setups they made but the secondary breaker box was the inverter itself and only one circuit, with everything else shed.

Since the 50 amp Rvs are 240 volt the three wires would be the neutral and the 2 hot leads would it not?
Using such in a 30 amp situation would suggest switching the neutral and ground and hot wire.
If I understand correctly, switching the ground would be of no value in any situation.

[Road Toad]

Our transfer switches, one original and one added, both are Generator priority; if wired as recommended in the lid of the box. Specifically, the manufactuers schematic labels the "Gen input" to be wired to the switches terminals that share the "coil" connection. Whichever source drives the coil is the "priority" source; again, if I understand correctly.
Rational being that IF both sources are present, the "coil-sharing" one is goint to be the one that is connected; hence "priority".

[booster]

Originally Posted by RoadToad@live.com

Since the 50 amp Rvs are 240 volt the three wires would be the neutral and the 2 hot leads would it not?
Using such in a 30 amp situation would suggest switching the neutral and ground and hot wire.
If I understand correctly, switching the ground would be of no value in any situation.

The wiring diagram shows where to put jumper wires to run it on 120v input.

[Road Toad]

Originally Posted by booster

The wiring diagram shows where to put jumper wires to run it on 120v input.

Yes, I see that now; interesting box.
Thanks for the pointout.

[booster]

Originally Posted by RoadToad@live.com

Yes, I see that now; interesting box.
Thanks for the pointout.

In actuality, you would probably only need the jumpers if you were doing the power shedding with two separate 110v boxes with a 110v input, and you would just use one wire of two hots for the inputs and only one of box outputs plus neutral. They appear to be taking advantage of the two out of phase legs to two boxes to facilitate easy power shedding, so pretty smart, but limits the ability split up the normal power use a bit.

[Road Toad]

Originally Posted by engnrsrule

Roadtoad and Booster...

I saw the $79 one and its fine but due to space consideration I got this one that has a smaller footprint.
https://www.amazon.com/dp/B00F84S3KM.

A three pole option I saw was a 50 amp model with the requisite small footprint for $186. It would require two to ensure full isolation across the system. However my concern is whether I would be compromising safety by not connecting the grounding bus. In a 50a system there are 4 wires - 2 hots, 1 neutral and ground, and such installation would employ the shared ground bus.

This is the one we used in my son-in-laws Pleasure Way.

The foot print is smaller but height is greater. Which worked well in the space he had available.
https://www.amazon.com/WFCO-T30WM-Am...392361&sr=8-28

[markopolo]

Originally Posted by RoadToad@live.com

Since the 50 amp Rvs are 240 volt the three wires would be the neutral and the 2 hot leads would it not?
Using such in a 30 amp situation would suggest switching the neutral and ground and hot wire.
If I understand correctly, switching the ground would be of no value in any situation.

Just so other folks reading this don't get confused, 50 Amp Rv's are 120V not 240V. The 4 wires are 2 x hot, 1 neutral & 1 ground. Each hot feeds it's own 120V load center. Other wires shared. Example:120V Air conditioner #1 is fed by load center #1 and 120V air conditioner #2 is fed by load center #2.

[booster]

Originally Posted by RoadToad@live.com

This is the one we used in my son-in-laws Pleasure Way.

The foot print is smaller but height is greater. Which worked well in the space he had available.
https://www.amazon.com/WFCO-T30WM-Am...392361&sr=8-28

The problem is that is a two input one, which there are lots of available. The linked one is a rare bird in that is appears to RV oriented instead homes and with three inputs so get genny, shore, and inverter all tied into on unit.


Aims used to make a 3 input 30 amp, 110v, unit but I think it has been discontinued for quite a while. It did have poor reviews on Amazon for reliability when it was out, though.

[Road Toad]

Originally Posted by engnrsrule

Roadtoad and Booster...

I saw the $79 one and its fine but due to space consideration I got this one that has a smaller footprint.
https://www.amazon.com/dp/B00F84S3KM.

A three pole option I saw was a 50 amp model with the requisite small footprint for $186. It would require two to ensure full isolation across the system. However my concern is whether I would be compromising safety by not connecting the grounding bus. In a 50a system there are 4 wires - 2 hots, 1 neutral and ground, and such installation would employ the shared ground bus.

Our X1 is the $79 one; our x2 is Piggy-backed physically onto tne load center; original to the Roadtrek .

https://mightytext.net/zELnAM

[engnrsrule]

RoadToad, switching the grounds completely isolates the unused power sources, which goes back to the need to avoid potential multiple neutral-ground bonds.

[Road Toad]

Originally Posted by engnrsrule

RoadToad, switching the grounds completely isolates the unused power sources, which goes back to the need to avoid potential multiple neutral-ground bonds.

Avoiding N-G bonds I am onboard with.

Switching grounds, not so much.

Our Tech school teachings were to never detach or interrupt an ACTIVE attached Ground.

If it is actually carrying current, which is it's job in a fault situation, it becomes an arc source (welder) if switched.

All source Grounds should be permanently chassis and earth grounded.

Uninterruptable.

[booster]

Originally Posted by RoadToad@live.com

Avoiding N-G bonds I am onboard with.

Switching grounds, not so much.

Our Tech school teachings were to never detach or interrupt an ACTIVE attached Ground.

If it is actually carrying current, which is it's job in a fault situation, it becomes an arc source (welder) if switched.

All source Grounds should be permanently chassis and earth grounded.

Uninterruptable.

I kind of agree with the final statement. In general yes, but not always with RVs in a couple of cases. Unless you drive a ground rod they can't be earth grounded when off shore power, so all the bonding at the sources has to be at that source, usually generator or inverter. There is a the problem of inverter chargers that can't be uninterruptible because they have to bond and unbond based on whether or not shore power is connected so you can't disconnect it from the mains out of it to the outlets and it sees both shore and inverter power AC inside itself. The ground in an RV is not an earth ground at all unless there is a connection to ground, so it has the potential to carry voltage if the bonding is not only at the inverter. If that voltage is high enough, you get can tingled or zapped between the chassis and true earth like a water pipe.

[Road Toad]

Originally Posted by booster

I kind of agree with the final statement. In general yes, but not always with RVs in a couple of cases. Unless you drive a ground rod they can't be earth grounded when off shore power, so all the bonding at the sources has to be at that source, usually generator or inverter. There is a the problem of inverter chargers that can't be uninterruptible because they have to bond and unbond based on whether or not shore power is connected so you can't disconnect it from the mains out of it to the outlets and it sees both shore and inverter power AC inside itself. The ground in an RV is not an earth ground at all unless there is a connection to ground, so it has the potential to carry voltage if the bonding is not only at the inverter. If that voltage is high enough, you get can tingled or zapped between the chassis and true earth like a water pipe.

In absense of true "earth" as a ground, (while rolling on rubber tires), the Chassis is "Earth".
Is it not?
I am failing to see the problem.
Though we can not alter the Inverter designs I don't see the problem with not switching the Gnd in any 30 amp xfer switch application.

Your last sentence is true regardless of onboard configuration of Gnd switching.

[Road Toad]

Not being confrontational here. I have the utmost respect for the obvious knowledge of Booster, Marco, other Forum members.
Not withstanding failure mode scenarios, I just literally do not see the switched Gnd issue.