Transposing Gen/Shore power in Xfer switch?

[94TurtleTop]

Installing a new 30 amp automatic transfer switch, and I've noted that several have decided to connect their generator side to the "always on shore" section of the switch and connecting the shore to the "gen" side of the switch so that it only comes on when shore is connected and pulls the contactor into that mode.

This is to prevent the battery from being drained by the magnet in the contactor.

Is this accepted as a good idea? Any con's I'm missing?

[twinboat]

What battery ? The ATS gets its power from 120 volt sources.
When you start the generator, the switch senses 120 volts and starts a 30 second delay before switching to generator power.

Wiring it backwards will have the relay pulled in all of the time your on shore power and you'll be starting the generator against anything switched on.

[traveldawg]

This is the first I've heard of this. I really don't understand the logic of wiring something backwards that works quite well wired correctly.

As point out, the switch is independent of any battery function.

So, for me, this is a bad idea with no value or upside.

[94TurtleTop]

Originally Posted by traveldawg

This is the first I've heard of this. I really don't understand the logic of wiring something backwards that works quite well wired correctly.

As point out, the switch is independent of any battery function.

So, for me, this is a bad idea with no value or upside.

I believe I may have been reading the post of someone with a solar setup instead of a generator, his point being that holding in the contactor uses a small amount of constant battery power.

Thanks for the clarity all, I have wired it conventionally.

[twinboat]

When using an inverter, you would wire it backwards. Since the switches are generator priority, an inverter would keep it powered. Backwards, shore power holds it closed and when shore power goes away, it defaults to inverter.

[samsonsdriver]

I have replaced one of these before. I don't recall any DC being used. Any relays being pulled in are ac powered. I don't believe battery drawer would be an issue. I believe it would just change the priority of power.

[Stircrazy1]

Originally Posted by 94TurtleTop

Installing a new 30 amp automatic transfer switch, and I've noted that several have decided to connect their generator side to the "always on shore" section of the switch and connecting the shore to the "gen" side of the switch so that it only comes on when shore is connected and pulls the contactor into that mode.

This is to prevent the battery from being drained by the magnet in the contactor.

Is this accepted as a good idea? Any con's I'm missing?

I did this with my inverter instead of a generator and I can say don't do it. what happenes is you burn out your ATS faster as it is powering the selinoid to allow shore power in with that configuration.

in a proper hook up the shore power is normaly open, which means the selinoids are not working to allow shor power. the generator side is normaly closed and when power is put to that line it energises the selinoid and openes the shore power side and closes the generator side. so if you hook it up backwards when ever you are hooked to shore power the selinoid is energised which eventual burns them out if you normaly have your rv plugged in.

I tried it backwards and my thinking was that if my shore power went out the inverter power wpuld automaticly come on so I could leave the inverter on but not worry about using any power from it unless the shore power went out. the normal way if I turn on the inverter it will shut off the shore power.

there is no way you should drain the battery if it is hooked up properly as when on shore power no selinoid is active, its only when the genny starts up it sends power to the selinoid and switches over and thats all 120V. in a inverter setup I could see that happening if people had their inverter on while they are pluged into shore power as it would be running off the batteries for 120V but your converter would be charging.. a lot of mess for no reason.. I have a remote switch for my inverter so I tun the switch on the inverter to remote then I can turn it on or of from the wall plate so if the shore power goes out it takes me 2 seconds to get up and turn on the inverter now.

now it is hooked up properly and I just don't turn on the inverter unless I intend on running off of it.

Steve

[Stircrazy1]

Originally Posted by twinboat

When using an inverter, you would wire it backwards. Since the switches are generator priority, an inverter would keep it powered. Backwards, shore power holds it closed and when shore power goes away, it defaults to inverter.

I wouldnt ever do that again, see my post above.

[twinboat]

Originally Posted by Stircrazy1

I wouldnt ever do that again, see my post above.

If you look at any 50 amp auto transfer switch, one of the 2 relays is always powered on shore power. Same relays, and they last for ever.

[Stircrazy1]

Originally Posted by twinboat

If you look at any 50 amp auto transfer switch, one of the 2 relays is always powered on shore power. Same relays, and they last for ever.

mine is 50 amp and no, one is not alway powered. they come in normaly closed and normaly open for the teo legs. (closed meaning power will flow through) so the normal is the shore power is a normaly closed selinoid and the generator is a normaly open. so no power is required to hold them in thoes states. so as long as you are running off shore power and the generator/inverter is shut off the only power consumed will be the monitoting circuit (the little PC board that senses when power changes and sends signals to the selinoids when it does) if you lose power on your shore circut the pc board and the circut board sences power on the generator/inverter side, it will send power to open the shore power selinoid and close the generator/inverter side.. both these operations require power to hold the selinoids in that position.

when I burnt mine out because I was running it backewards (only got 4 years out of it) I was able to wire it back to proper as the selinods didn't have to move or be powered to let the shore power work in a standard setup, I just wasnt able to use the other side untill I put a new 50 amp transfer switch in.

I am trying to source the raw selinod switched that 90% of the manufactures use to rebuild my old one right now, Just haven't taken it apart to see if there is numbers I can look up yet.. winter project.

[Old-Biscuit]

Back in 2007 just a few months into our FT travels the 50A ATS failed, would not close in either position (shore nor gen)

Parallax customer service was pretty good.......they overnighted a new ATS after they received the claim with report from an Authorized RV Tech
*I had already diagnosed the issue, Mobile Tech verified

Next day Mobile Tech returned with New ATS.....installed it and tried it 4x
(2X for Shore and 2X for Gen) Then switched back to Shore and it failed to swap....still had power via Gen but would not switch to Shore
Called Parallax and they responded with.....please send it back we have been having some issues with them ?????

Told Mobile Tech to get me some supplies........3 large junction boxes, 20 or so feet of Red, Black, White, Green 6ga wire, Subpanel and dual 50A interlocking Circuit Breakers

WE (Tech and I) rewired the Shore--Gen---Main, installed the subpanel with the 50A CBs (one set for Gen, one set for Shore)
Viola ----Manual ATS

Just takes a flip of the CBs and if anything breaks.....hardware store

Simple.........

[ewarnerusa]

I run an ATS for my inverter in the "backward" configuration, shore power will be the AC power source if it is available. I only turn on the inverter when needed and it powers the whole panel. Converter is on its own breaker and is basically always in the off position (I rely on the solar for battery charging). When I first installed the ATS, I did it according to the diagram and I thought its logic was backward when I was testing it out and things would remain on inverter power even if shore power was also available. So I switched it around and haven't looked back since. Our situation is that the camper is very rarely running on true shore power, only for some pre-trip prep so the fridge can cool down and the water heater can heat the water on AC power. When we use the camper, it is in an off-grid situation. The appliances are running on propane and I tend to only turn on the inverter when we want some AC power for something. Is what I'm reading in this thread saying that this is bad for the ATS?

[Sunnyfalls]

I don't see the need for using an automatic transfer switch at all when a labeled and robust manual switch can accomplish the same purpose and also enable you to have more power capability too. And using circuit breakers as switches will shorten their life and potentially cause them to not trip when they need to trip. And solar panels, their charge controllers and the batteries that they charge are a DC system and not AC system, so they are not affected at all and have nothing to do with this subject.

We have a small Casita travel trailer. It was modified to use 120/240VAC 50A (12,000 Watts) shore power for our 120/240VAC appliances (e.g., induction cooktop and electric/propane tankless water heater). This trailer was also modified to create an independent 120VAC 20A (2,400 Watts) circuit using a 100AH LiFePO4 battery, 3,000 Watt Inverter and 20A circuit breaker. A 200 Watt portable solar panel suitcase is used to charge our battery when dry camping.

A manual switch rated for 30A is used to connect this 120VAC 20A circuit to either Inverter Power, No Power or Shore Power (see photo). When we have shore power, we can use it to power this independent circuit or we can also use our Inverter to power this circuit and thereby increase our overall power capability to 14,400 Watts. Being able to use BOTH Inverter Power and Shore Power at the same time is useful because when we are on shore power, our induction cooktop uses 3,500 Watts and out tankless water heater uses 6,500 Watts. And when we don't have shore power, we use the Inverter to power this circuit for ALL our 120VAC dry camping power needs and we use propane for our cooktop, furnace, refrigerator and tankless water heater. We use our lightweight, quiet, reliable and small propane modified Honda EU2200i generator for operating our air conditioner on the rare occasions it needed as we can keep our small, entirely reflective white trailer mostly in the shade while always keeping our solar panels in direct/full sun.

Gayle & Bob
"Los Gatos Casita"

[twinboat]

Originally Posted by Stircrazy1

mine is 50 amp and no, one is not alway powered. they come in normaly closed and normaly open for the teo legs. (closed meaning power will flow through) so the normal is the shore power is a normaly closed selinoid and the generator is a normaly open. so no power is required to hold them in thoes states. so as long as you are running off shore power and the generator/inverter is shut off the only power consumed will be the monitoting circuit (the little PC board that senses when power changes and sends signals to the selinoids when it does) if you lose power on your shore circut the pc board and the circut board sences power on the generator/inverter side, it will send power to open the shore power selinoid and close the generator/inverter side.. both these operations require power to hold the selinoids in that position.

when I burnt mine out because I was running it backewards (only got 4 years out of it) I was able to wire it back to proper as the selinods didn't have to move or be powered to let the shore power work in a standard setup, I just wasnt able to use the other side untill I put a new 50 amp transfer switch in.

I am trying to source the raw selinod switched that 90% of the manufactures use to rebuild my old one right now, Just haven't taken it apart to see if there is numbers I can look up yet.. winter project.

Maybe yours but mine and many others work as I stated. When I plug into shore power i hear it clunk as it pulls in.