mena661
Southern California
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My "new" MH has a 50A transfer switch (generator and shore power). I want to add in my inverter (whole house) and install a second ATS but I'm not exactly sure where I should install it. My thinking is the best/easiest would be to install on the shore power side of the OEM ATS. What do you guys think? BTW, I won't be able to inspect the unit itself till tomorrow at the earliest.
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dougrainer
Carrolton, Texas
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The Inverter is NOT a 50 amp Inverter. They usually ONLY transfer 30 amp service and that is the PASS thru rating. The Inverter should have its OWN 30 amp transfer switch. You do realize that a 50 amp RV and 50 amp transfer switch actually transfers 100 amps total? You NEVER install an Inverter and run the complete RV shore or APU power thru it. The Inverter is NOT rated to do that. Doug
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wolfe10
Texas
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What is inverter output. Depending on its output and what you want to run from those inverter-supplied circuits, a 30 amp (single HOT) is what you need.
Give us more details on your system and what you want to do and we may be able to help.
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smkettner
Southern California
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What is the priority order?
1 Generator
2 Shore
3 Inverter
Or something else?
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mena661
Southern California
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300W inverter currently that will be upgraded to a 2000W. Want to run whole house, no sub panels. Don't have a problem with remembering to switch stuff off or just plain not use it as that's what we do now (besides where we camp, accidentally running the A/C on a 300W inverter won't happen). I prefer the simplicity and cheaper cost of wiring whole house. 2000W inverter would run MW and maybe the convection oven too (it only has a convection oven) plus all receptacles. The coach has tube fluorescent lighting that I'm not sure if it's 120V or 12V. If it's 120V then I'll be running that from the inverter too.
smk,
Hmmmm. Probably...
1. Inverter
2. Generator
3. Shore
But would it make more sense to make sure the inverter is on the normally closed side of the both ATS's?
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smkettner
Southern California
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If you put the inverter on the normally closed side, the TS will switch power to the other source when present. This will not give inverter #1 priority.
I would think if you were on inverter and started the generator you would want generator power for example. Yes you can turn off the inverter but still it is not really first priority.
Although there might be other reasons to stay on inverter while the generator charges the battery. Could reset some electronics when the TS switches.
Just stuff to think about.
* This post was
edited 07/13/12 02:26pm by smkettner *
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MrWizard
Traveling
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better look at your ATS before you decide what to do
my 50 amps ATS has (2) relays, one for shore, one for generator
each one operated by power from that input line, and there is a mechanical interlock between them, that is operated by whichever side is energized to prevent the other side from pulling in
do you really want the constant drain of an ATS relay powered by the inverter
too avoid this i think you will need a manual switch 4 pole switch rated for 50amps placed between the shore side of the OEM ATS and the new inverter
output side of the switch to the house, the two inputs one from the inverter, and one from the existing output of the shore side of the ATS
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2oldman
Winchester WA
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mena661 wrote:best/easiest would be to install on the shore power side of the OEM ATS. I'm not by any means an expert on 50a. I picture this installation as being 'just another 30a ac source' like when you only have a 30a socket at the CG. How does that work? I would find which wires that service utilizes, and stick the inverter there.
I'm also not too familiar with OEM ATSs.. my vision is an inverter with its own ATS.
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DryCamper11
Hartford
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On mine, I bought two 30A contactors and a 6 second delay relay from Grainger's to make two Transfer Switches - TS#1 and TS#2 - in a single box. The generator and shore power were connected to TS#1 and it switches before the AC panel to power the entire RV. If the generator runs, it drives the delay relay and 6 seconds after it sees good steady AC power, the delay relay fires the contactor for TS#1 and the whole RV switches to gen power.
TS #2 is after the panel on the single circuit that runs all the 120V plug-in sockets (except AC, refrigerator and converter). When I installed it, the AC was already on a separate circuit and I added two other separate circuit breakers for the converter and refrigerator. The refrigerator required running another AC line. That was the hardest part. The converter was integrated into the bottom half of the AC circuit breaker panel and I just needed to add two more breakers and move one wire.
When I turn on the inverter, TS #2 fires immediately and all the 120VAC sockets are on the inverter. It's worked great for the last 20 years.
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DryCamper11
Hartford
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MrWizard wrote:my 50 amps ATS has (2) relays, one for shore, one for generator each one operated by power from that input line, and there is a mechanical interlock between them, that is operated by whichever side is energized to prevent the other side from pulling in
That seems like an odd design. There's no default position. It seems that if both were off - no shore and no inverter, nothing would be connected.
Are you sure it works that way - one relay for gen and one for shore?
It would work with that design, but I think it would be more costly. You'd need to switch both phases with each relay, although you could use single throw relays. If I saw two relays in a 50A ATS I'd suspect one was being used for each 120VAC side of the 50A/240V power source. That would only need to switch one phase for each relay, but you'd use double throw relays.
The default position would be both relays off - sending shore power on both sides. If the generator came on, I'd expect both to pull in, switching both phases, with a common interlock to make sure they both pull in or drop out together.
I've never seen a 50A ATS, which is why I ask.
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