Inverter hookup

[Gerald55]

A couple of questions about installing an inverter. I'm looking to put one in my 2008 Pleasureway Excel, which didn't originally come with one wired into the 120V system (it did have a small 400W standalone one for the TV only).

Can I simply wire the output of the inverter right into an existing 120V outlet in the RV, e.g., using a male-to-male cord like this:

http://www.amazon.com/Dual-Male-12-Gauge-Connection-Extension/dp/B0035Z13FI/ref=cm_cr_pr_product_top?ie=UTF8

In that case, what happens when I connect to shore power and the inverter is on? Will it just play nice by default, or does it need some kind of internal transfer switch capability to not blow up?

I do an unused transfer switch in my rig since it's wired for a generator but doesn't have one, so maybe I can just use that input?

Any recommendations on brands? I'm looking for 1500W or so, and don't want the dirt cheap variety, but maybe the next level up. I especially want one whose fans are variable, i.e., they only go on if needed to cool the inverter and would generally stay off or run at a low speed if I'm pulling 100W rather than 1500W (which will be very common, e.g., just a laptop).

Some of the "good" inverters I've seen seem to run the fans at nearly full blast regardless of draw.

[Gerald55]

I ended up getting it all hooked up OK. I used a bare NEMA 5-20P plug which I attached to a short length of 12-3 SJOOW cable, which I wire directly into the transfer switch. It is all working nicely now, except for some noise which I describe here...

[BendOrLarry]

Veebyes wrote:
BendOrLarry, be sure the waterheater is off too. Big power user. Maybe more than a 1000W inverter will handle. If it does it will kill your battery bank in a hurry.

Good job at isolating the inverter from shore power. In my boat I had a 1000W inverter feeding the genny input on the circuit breaker board. When using the genny I'd simply unplug the output at the inverter. On shore power I'd turn the genny circuit breaker off at the panel.

One night I forgot to turn the circuit breaker off. BOOOOM!!! One toasted inverter as it got backfed.

You are correct about the water heater, but I never have it on anything other than propane.

[Veebyes]

BendOrLarry, be sure the waterheater is off too. Big power user. Maybe more than a 1000W inverter will handle. If it does it will kill your battery bank in a hurry.

Good job at isolating the inverter from shore power. In my boat I had a 1000W inverter feeding the genny input on the circuit breaker board. When using the genny I'd simply unplug the output at the inverter. On shore power I'd turn the genny circuit breaker off at the panel.

One night I forgot to turn the circuit breaker off. BOOOOM!!! One toasted inverter as it got backfed.

[BendOrLarry]

I just installed a 1000 Watt pure sinewave inverter in my class c. It already had a transfer switch for the generator. I added an additional transfer switch. I took the output of the first transfer switch (that would normally go to the distribution panel) and routed it to the new transfer switch shore power connection. I then ran romex from my inverter to the generator connection of the second transfer switch. I then added a relay to the hot wire of the convertor. The relay is a 120 volt normally closed relay, so when the inverter turns on, it opens (turns off) the converter. I also added a 150 amp circuit breaker between the battery bank and the inverter. All I have to do is be sure the microwave circuit breaker is off and the fridge is turned on to propane only and all my 120 volt outlets are hot. I may use a second set of output connections on my relay to disable the microwave automatically when ever the inverter is on. I like everything to be automatic and simple.

[Veebyes]

Running the inverter output to the generator, which you don't have, would have supplied 'the house' will work. BUT. It is a huge BUT. If you leave the inverter on & plug into shorepower you could get a very loud BOOM followed very closely by stinky smoke & the inverter gets back fed. Be sure the inverter is turned off. Better still, put a circuit breaker between it & the house

You will also need to be very aware of what 120AC circuits are turned on when on the inverter. Overload the inverter & it will shut down. If you don't have enough battery bank you will kill that in short order.

My 2000W inverter feeds the main 120VAC panel. First thing done when setting up where inverter will be used is make sure water heater & fridge are left on propane. Circuit breakers for high draw items like heaters & microwave are turned off.

[N-Trouble]

Gerald55 wrote:

Almot wrote:

N-Trouble wrote:
I was powering our TV off my inverter last trip, and my son fired the onboard genny to run the microwave. It didn't seem to affect anything that I could tell

I think you were pushing your luck. Even if generator didn't damage the batteries because converter was off, it was still backfeeding 120V into the inverter.

It is almost certainly the case that shore power and the generator are connected to AC system through a transfer switch that only lets one or the other power the house AC at one time (generally it will choose the generator if both are on). At least no manufacturer would release a rig that didn't work that way.

So when you hooked your inverter up to shore power, and then turned on the genny, you were probably simply powering everything via the generator at that point, and the inverter was effectively disconnected at the transfer switch.

Correct. Trailer has a transfer switch and when my son fired the gennny it switched to that source. He ran the microwave for about a minute.

[Gerald55]

Almot wrote:
Not sure there was a transfer switch. He said that used a shore power cord - with all the mental work that comes with this method, i.e. remembering to disconnect the loads. Doable.

I think the inverter plugged into the shore power receptable is besides the point. He has a "built in" genny and shore power. There must be a transfer switch in there somewhere or he would have already blown something up when on shore power and starting the genny. The only other safe possibility I can think of is that he plugs the AC output of the genny in to the shore power output to use the genny, but that's excluded here because that wouldn't have been possible in the scenario above (since the inverter was plugged in).

There is, of course, always the possibility that the shore power and the genny are both wired into the AC system without a switch, and nothing has "gone boom" yet only because they've never been on at once, but in that case the failure is having a system configured like that, and nothing particularly to do with inverters (it could as well have been shore power in the scenario mentioned).

[Almot]

Gerald55 wrote:

It is almost certainly the case that shore power and the generator are connected to AC system through a transfer switch that only lets one or the other power the house AC at one time (generally it will choose the generator if both are on). At least no manufacturer would release a rig that didn't work that way.

So when you hooked your inverter up to shore power, and then turned on the genny, you were probably simply powering everything via the generator at that point, and the inverter was effectively disconnected at the transfer switch.

Not sure there was a transfer switch. He said that used a shore power cord - with all the mental work that comes with this method, i.e. remembering to disconnect the loads. Doable.

[Gerald55]

Regarding my earlier question about how to connect to the 20A GFCI, I ended up going with a bare 5-20P plug:





I can just bring my romex all the way to the plug and attach it, avoiding one set of additional pigtails. $15 locally - seems a bit rich, but it solves the problem nicely I think.

[Gerald55]

Almot wrote:

N-Trouble wrote:
I was powering our TV off my inverter last trip, and my son fired the onboard genny to run the microwave. It didn't seem to affect anything that I could tell

I think you were pushing your luck. Even if generator didn't damage the batteries because converter was off, it was still backfeeding 120V into the inverter.

It is almost certainly the case that shore power and the generator are connected to AC system through a transfer switch that only lets one or the other power the house AC at one time (generally it will choose the generator if both are on). At least no manufacturer would release a rig that didn't work that way.

So when you hooked your inverter up to shore power, and then turned on the genny, you were probably simply powering everything via the generator at that point, and the inverter was effectively disconnected at the transfer switch.

[Almot]

N-Trouble wrote:
I was powering our TV off my inverter last trip, and my son fired the onboard genny to run the microwave. It didn't seem to affect anything that I could tell

I think you were pushing your luck. Even if generator didn't damage the batteries because converter was off, it was still backfeeding 120V into the inverter.

[Gerald55]

Almot wrote:

Gerald55 wrote:
To clarify, this is about the permanent installation of an inverter in an inaccessible location, and it should be wired into the 120V system permanently.

So solutions like plugging the inverter into the shore power outlet don't work since, well, that's outside and can't be a permanent thing. Similarly for only plugging devices into the inverter as I need them (the inverter is not accessible).

Suicide cord will work, and the risk of being electrocuted will be high.

Plugging inverter into shore power outlet with a shore power cord and cheap Female30A/Male15A adapter will also work, and the hazard to you will be minimal, but you need to remember to temporary disable the converter and all the permanently wired 120V appliances like A/C and water heater. There still remains hazard to converter, inverter and batteries if you forget to disable something.

I don't think you've done your math yet. 400W inverter that you have, is fine for everything except few loads like microwave, and for those loads 1500W will be marginal. Get 2000W. 400W inverter doesn't need to be wired with short and beefy cable or mounted directly onto the battery.

I think all big inverters will have fan running as long as there is any load at all. You mount it where you can't hear it, and use a remote on-off switch. Inverters under 500W either don't have a fan, or you can get a 200-300W one that doesn't - for small loads this will be enough.

I've already picked the inverter by now: it's 2000W pure sine inverter, which should be adequate for all my loads (AC is out of the question) - especially since all normal household appliances (that is, with 5-15 plugs) will max out at around 1800W (15A). By all reports the fans don't turn on unless you are working it pretty hard, which is one of the reasons I got it.

The 400W isn't going to cut it for a variety of reasons:

1) It's not going to run some of the important 500W+ loads I have.
2) It's super loud even at 0 load.
3) It's a junk brand modified sine wave and doens't run my electric blanket.
4) It's hooked into the TV/entertainment system in a fairly intricate way (i.e., behind a relay so that everything 12V + 120V powers on all together). I don't really want to change that.
5) There aren't any free outlets on it, so I have to go behind my TV and unhook the existing stuff any time I want to plug something in. 6) It's not wired into the general 120V house wiring.

OK 4,5,6 are kind of redudant, but a list of 6 reasons it better than 4, right?

[N-Trouble]

I do the shore power cord thing and while it great that it powers the entire trailer, it power the entire trailer... Meaning yes you have to be aware of any loads on the AC system prior to hooking it up. I have blown a couple of fuses on my inverter as a result, but fuses are cheap and easy to swap out. Have to disable converter and put fridge on gas only mode.

I was powering our TV off my inverter last trip, and my son fired the onboard genny to run the microwave. It didn't seem to affect anything that I could tell

[Almot]

Gerald55 wrote:
To clarify, this is about the permanent installation of an inverter in an inaccessible location, and it should be wired into the 120V system permanently.

So solutions like plugging the inverter into the shore power outlet don't work since, well, that's outside and can't be a permanent thing. Similarly for only plugging devices into the inverter as I need them (the inverter is not accessible).

Suicide cord will work, and the risk of being electrocuted will be high.

Plugging inverter into shore power outlet with a shore power cord and cheap Female30A/Male15A adapter will also work and will be "permanent" for the duration of your stay, until you disconnect it. The hazard to you will be minimal, but you need to remember to temporary disable the converter and all the permanently wired 120V appliances like A/C and water heater. There still remains hazard to converter, inverter and batteries if you forget to disable something.

I don't think you've done your math yet. 400W inverter that you have, is fine for everything except few loads like microwave, and for those loads 1500W will be marginal. Get 2000W. 400W inverter doesn't need to be wired with short and beefy cable or mounted directly onto the battery.

I think all big inverters will have fan running as long as there is any load at all. You mount it where you can't hear it, and use a remote on-off switch. Inverters under 500W either don't have a fan, or you can get a 200-300W one that doesn't, and keep it accesible - for small loads this will be enough.