3 position Transfer Switch

swhitney wrote:
I have an older class A RV, I was thinking about installing an inverter but wasn't exactly sure on the wiring.

To me the easiest way if it's even available would be to have a 3 position transfer switch. If I were to be plugged into shore power then that would run everything or vice a versa, if the generator or shore power was not on or plugged in then the inverter would run.

Not trying to power the AC.


Thank you,
Sean

don't believe there is such a thing, Best to buy a inverter that has the TS built into it.taking a old MH and wiring in a Inverter that
incorporates the existing system is a big job

I don't think they make a 3-way, I would think it increases the failure odds quite a bit.

The installs I've read about used two switches, one to switch between shore/generator and down from that generator/inverter. Inverter was the "last choice" for ac power and shore was the "first choice."

Of course, the easy way could be an outlet for the generator and you just plug your shore power cord into it when you want generator power.

wiring two transfer switches off the generator doesn't seem overly complicated.

Generator turns on and kicks the inverter off and same for the 1st transfer switch. Does the transfer switch take priority from shore power?

I would have to turn the breaker off for the battery charger.

swhitney wrote:
wiring two transfer switches off the generator doesn't seem overly complicated.

Generator turns on and kicks the inverter off and same for the 1st transfer switch. Does the transfer switch take priority from shore power?

I would have to turn the breaker off for the battery charger.

A transfer switch basically takes two inputs (A and B, which can be wired to shore power and a generator). One input, usually A, is the default. This is where it will connect to for power if there isn't any stable power on B. When power appears on the B side and it's determined to be of proper voltage and stable, the transfer switch will disconnect from the A inputs and connect to the B inputs. If power is lost the transfer switch will return to the default position, and in this case attempt to get shore power.

I suppose you could wire two transfer switches up in series to be able to take power from three different sources, but that seems overly complicated and expensive. There has to be easier ways to achieve your goal since most RVs with inverters do that akready. In my RV I have an inverter switch that will supply power to a couple of 110v outlets when I'm not on shore power or running the generator.

Quick look on amazon for a 30 amp transfer switch is around 75 dollars. That seems like a pretty inexpensive route.

Please let me know if there is a better way.

Thank you,
Sean

30 amp TS in the main feed is fine. Low cost and simple. Do need to make sure the converter or battery charging system is turned off. Otherwise you create a power loop that will drain your battery fast.

Other issue is make sure air conditioner stays off and fridge and water are set to propane only.

Could also add small 15 or 20 amp transfer switch to just the branch circuits you need. Or a sub panel to only power what you connect.

Is this 300 watts for small stuff or 2000+ watts for microwave, coffee, toaster, hair dryer, etc? Need 4+ batteries for the large inverter.

I have two 6s batteries in series which are 215ah. I was planning on using the microwave to make popcorn or maybe watch TV at night. Are my batteries not enough?

If the microwave pull 100 amps for 2 minutes I would think that my batteries would handle that?

Yes

My Dometic microwave draws 160 to 175 amps from my 4 GC2s.
If it works then fine, if not you need to have a plan to add more battery.
Trouble is the voltage sags as you draw hard on the battery. Inverter will shut down between 10 and 11 volts. Keep in mind you need a more expensive sine wave inverter for the microwave to operate properly.

tv is easy.

There is nothing wrong with having two two-way transfer switches wired to switch between three power sources. There are various ways they could be hooked up depending on what your order of priority is for power sources.

If there were a three-input automatic transfer switch, it quite possibly may be two two-way transfer switches connected together internally. (It wouldn't have to be, but that would be one very reasonable way of constructing one.) Some suitably specified manual three pole (or two pole for a 30A RV), three throw switch would also work if you wanted a manual switching arrangement, though such switches are not particularly common.

A pair of golf cart batteries is adequate for limited microwaving, but barely. They would be more than enough for television watching. It might be more practical to make popcorn on the stovetop, with a whirly-pop if you're so inclined or in a saucepan with a lid if you're not. It only takes a couple or three minutes.