Morningstar Suresine 300 Installation

Mello Mike

I just bought this inverter from AZ Wind & Solar and had some questions about how to install it. Is this unit designed to have a single dedicated 110v AC outlet or is it supposed to tie in with my camper's AC system and route the inverter's AC power to ALL of the outlets in my camper?

And why are there only two AC output wires? Where's the ground? The Suresine has an earth ground but it's requires a big sucker (4 AWG) that supposed to tie in with my rig's ground. So there's no ground for my inverter outlet?

I've installed a Xantrex Freedom 10 Inverter/Charger and that unit was much easier to understand and install than this one

Would appreciate any input or ideas from those who have installed this unit already.

Thanx in advance.

BB.

Re: Morningstar Suresine 300 Installation

The SureSine is a True Sine Wave inverter with isolated output (basically, just two wires from the output tranformer). There is no Hot/Neutral wires at this point--it is a floating/isolated output.

You can either leave the wires floating, or you can pick one and jumper it to the green wire connection--That will make it the "neutral" wire and that green wire would be brought also two the three wire outlet.

For small systems, you do not need to ground reference the output of the inverter (and you should not do it with MSW inverters--always check the manual to be sure).

Now, you can wire the the inverter to all of your camper AC outlets--However, if you have a shore power connection, this is generally done through a transfer switch (something like this relay based transfer switch would be nice).

If you choose to ground the inverter and create a Hot/Neutral setup for your off-grid AC operation... It gets more complex. The Ground/Neutral connect is made at the shore power (typically main power panel). If you hard connect Ground/Neutral in your camper, you will create a grounding problem (and possibly a problem with ground fault interrupter outlets--if installed).

If you use a two pole transfer switch (like above), you would ground the "Neutral" at the inverter, then run the wiring to the transfer switch input.

That way, on shore power, the ground/neutral connection is made at the utility panel. And on off-grid power, the ground/neutral connection is made at the inverter's AC output. The transfer switch will select which one is active based on the active power source.

For generators, typically less than 3.5 kW or so are left floating. And larger generators have the ground referenced neutral.

I can go into more detail on why floating AC power is safer in many cases... But why in larger systems and/or with specific hardware (some florescent lighting, A/V systems, etc.) are better with ground referenced Neutrals.

-Bill

waynefromnscanada

Re: Morningstar Suresine 300 Installation

The TS 300 is an awesome inverter. I've had two of them in continuous use since 2007. One feeds my whole house 24/7 for lights (inside and out), this computer and a bunch of other things that need power always on. The other is dedicated to specific loads, only fires up as needed, and ends up running at least 75% of the time.
They can do either of the options you mentioned, a single outlet, or fed directly into your wiring. BUT, as BB indicated, it must NEVER be connected to your wiring, or anything else at the same time that those items are connected to shore power, unless of course you don't mind watching it sputtering, spitting sparks and belching smoke. Thus the transfer switch.

icarus

Re: Morningstar Suresine 300 Installation

Bill has it dialed, just make sure that you isolate it from shore power (or generator!) with a transfer switch. I simply jumped from one AC leg to the grounded side ( negative) lug from the battery which in turn is grounded.

Tony

Mello Mike

Re: Morningstar Suresine 300 Installation

Thanks, guys, for the input. I think I'll keep it simple and have two dedicated 110v outlets for this inverter. I guess I won't be connecting the Romex's ground wire.

icarus

Re: Morningstar Suresine 300 Installation

At the very least, fuse the input to the inverter. Ideally yo u would fuse the branch circuits as well, but is probbly not require, since a 30 amp fuse in the input (360 watts) would blow long before a 5 amp on the output. (~600 watts)

Tony

BB.

Re: Morningstar Suresine 300 Installation

If you plan on using the full rating of the 600 watt (10 minutes) of the TSW inverter, roughly the calculations will look like:

• 600 watts * 1/0.85 invrtr eff * 1/10.5 volts cutoff * 1.25 NEC safety factor = 84 amps

Your fusing and wiring should be designed for >84 amps.

-Bill

Mello Mike

Re: Morningstar Suresine 300 Installation

Yes, I plan on installing a 100 amp in-line fuse on the DC input side and a 3 amp in-line fuse on the AC output, just as the installation instructions call for.

This is a great site, BTW. You guys are great.

BB.

Re: Morningstar Suresine 300 Installation

Personally, I am not sure I would use a 3 amp fuse--It would not support the rated 600 watts for 10 minutes.

Myself, I would not even use an output fuse... You are going to probably use 14 awg and 120 VAC rated cords/components/appliances (good for 15-20 amps). There is no way this inverter can exceed their input safety ratings.

Of course, this my personal opinion. I cannot tell you to go against the manual (even if the manual does not make sense).

-Bill

waynefromnscanada

Re: Morningstar Suresine 300 Installation

BB. wrote: »

Personally, I am not sure I would use a 3 amp fuse--It would not support the rated 600 watts for 10 minutes.

Myself, I would not even use an output fuse... You are going to probably use 14 awg and 120 VAC rated cords/components/appliances (good for 15-20 amps). There is no way this inverter can exceed their input safety ratings.

Of course, this my personal opinion. I cannot tell you to go against the manual (even if the manual does not make sense).

-Bill

Bill, your "personal opinion" has been my experience. Overload the inverter and it just shuts down. Two more times it will try an auto-restart, with a few seconds wait between tries, after which it shuts down, stays shut down, and needs to be manually reset, either by disconnecting the 12 volt supply until the inverters red LED overload indicators go out, or signaling the inverter to shot down (as if it weren't already shut down) by using the remote switch if one is connected.
I strongly suspect that the recommended 3 amp fuse in the output line is there to protect the inverter from catching fire in case someone neglects using a transfer switch and the inverter accidentally gets left connected to a load or wiring, while at the same time a generator, or shore power is also connected to that same load or wiring. the 3 amp fuse won't protect the inverters output circuitry from destruction in such cases, but it should prevent a fire.
By the way, there is totally no way that my inverters could accidentally be connected to a generator etc, so neither of my TS-300's have fuses in the output. That's not to say I shouldn't have such fuses, I just don't. Saw no need.

icarus

Re: Morningstar Suresine 300 Installation

I have mine wired with a DC breaker on the input side, 50 amp. I then have it hard wired to an AC load centre, feeding branch circuits, breaker with 15 amp breakers, using #14 wire.

It is. Bit of over kill, since I never run more than ~100 watts total, but when I fire the genny, I may run a vacuum, a heat gun or soldering irons, or very rarely a A/C window unit.

Tony

Mello Mike

Re: Morningstar Suresine 300 Installation

Hi again, Guys. I need your opinions. After surveying my camper for places to mount my inverter, I've come to the conclusion that the best place to install it is in the generator compartment. My camper came generator ready with all of the wiring in place, including 4-AWG DC cables going to the battery compartment and 12/2 AC wiring going to the Generator Transfer Relay Box. I'm not going to install a generator in this compartment so it really is a perfect location.

Connecting the DC side is easy, no need to explain that further. On the AC side all I need to do is disconnect the generator input wiring feeding the Generator Transfer Relay and connect that to my two dedicated AC outlets.

Here's my only concern. The installation instructions call for a 6-AWG AC ground, but the wiring to the generator compartment only has 12-AWG. Is having this large of a ground wire really necessary for a 300 watt, 2.6 amp inverter?

BB.

Re: Morningstar Suresine 300 Installation

The ground wire needs to be able to "sink" enough short circuit current to blow the DC input power fuse you are using. Wire cannot be too small of gauge or too long (too much voltage drop and it will not draw enough current to blow the fuse).

So, no, the 6awg wire is not overkill--because it is not the 3 amps of the 120 VAC that is the major source of short circuit current--it is the XX Amp DC fuse/breaker that would be the source of high current flow...

12 AWG wire has ~235 amp rated fusing current... if you are running a 80-100 amp fuse/breaker--then I would go heavier. 12 AWG is a bit light to blow a 80+ amp fuse/breaker.

-Bill

Mello Mike

Re: Morningstar Suresine 300 Installation

BB. wrote: »

The ground wire needs to be able to "sink" enough short circuit current to blow the DC input power fuse you are using. Wire cannot be too small of gauge or too long (too much voltage drop and it will not draw enough current to blow the fuse).

So, no, the 6awg wire is not overkill--because it is not the 3 amps of the 120 VAC that is the major source of short circuit current--it is the XX Amp DC fuse/breaker that would be the source of high current flow...

12 AWG wire has ~235 amp rated fusing current... if you are running a 80-100 amp fuse/breaker--then I would go heavier. 12 AWG is a bit light to blow a 80+ amp fuse/breaker.

-Bill

Thanks, Bill. Sorry, but I'm not comprehending completely what you're saying or maybe I wasn't clear in my last post. Both of my DC cables (positive and ground) are 4-AWG. My question was about the size of the AC Ground (Green) Wire. Does that need to be 4 or 6-AWG or is 12-AWG sufficient?

Mike

BB.

Re: Morningstar Suresine 300 Installation

Hmmm... There is the ground from the Inverter's big old ground screw that they recommend to be ~6 or 4 awg (don't remember the exact number)... And there is the green wire ground that you would use in a 3 wire outlet. The outlet ground only needs to carry around:

• 600 watts / 110 VAC = 5.5 amps continous

Usually, we use 14 AWG wiring minimum for ground (and power) wiring for 15 amp 120 VAC branch circuits--And while you could use smaller, I would try to keep the normal 14 AWG minimum wire gauge (keep voltage drop down and you can connect those outlets to generator/shore power later with or without a transfer switch) and not need to worry about rewiring the branch circuit to carry rated load of 15 amps.

So--Short answer is yes, go ahead and use 14 or 12 AWG wire for your green wire ground for the inverter's branch circuit AC green wire connection. It is perfectly safe.

You could also jumper to the 4 awg green wire to inverter bonding screw if you have that handy too. Over-sized wiring generally does not cause problems provided appropriate sized fusing/breakers are used.

-Bill

PS: You do see there are three high current connections on the input to your inverter? DC+, DC-, and Safety Ground.

DC Ground is not really clear to me in this context what you are typing about.

Yes, in automotive DC systems, there is not really any difference between DC- and DC Ground because the chassis of the appliance (like car radio) is both DC- and DC ground.

In this inverter's setup--They are actually different there is +/- power input (not ground referenced that I am aware of)... And there is the DC safety ground to metal case connection. Hence the reason for three heavy "DC wires" going to the unit.

Mello Mike

Re: Morningstar Suresine 300 Installation

BB. wrote: »

DC Ground is not really clear to me in this context what you are typing about.

Yes, in automotive DC systems, there is not really any difference between DC- and DC Ground because the chassis of the appliance (like car radio) is both DC- and DC ground.

In this inverter's setup--They are actually different there is +/- power input (not ground referenced that I am aware of)... And there is the DC safety ground to metal case connection. Hence the reason for three heavy "DC wires" going to the unit.

Awesome! Thanks, Bill. That makes things a lot simpler if I can use the existing 14awg DC safety ground wire to ground my inverter. Just wondering why Morningstar called for such a large (6 or 4awg) safety ground wire to begin with.

Sorry about the confusion created by my use of terms. When I say DC ground, I'm really saying DC negative. That comes from my time working on aluminum trailers when the terms, ground and negative, are interchangeable like you mentioned.

BB.

Re: Morningstar Suresine 300 Installation

Basically, they are protecting against the Inverter metal body being energized by a loose wire or nut that fell inside the inverter and shorted DC+ to Chassis.

If the inverter was mounted on wood or a poor ground--all of that short circuit current from DC+ would need to be carried back from the inverter to the Battery- terminal (if the battery is negative grounded).

If the metal the inverter is well grounded (for UL requirements--we would have to have a bond wire from each panel to the "frame ground" or solid bolts/screws with lock washers to attach skins and panels) then you could used the metal panel in your generator box as the "earth ground" for the metal inverter chassis.

With modern RVs and other vehicles, they frequently use double stick tape to bond metal panels together--so there may not be a "guaranteed" metal "earth bond" on many components. Hence, why a separate ground wire is a good idea if you don't know how the vehicle was constructed.

-Bill

Mello Mike

Re: Morningstar Suresine 300 Installation

Just completed this installation earlier today. The installation was pretty simple, especially since I ended up installing the inverter in the generator compartment. All of the DC wiring and most of the AC wiring was already done which was pretty sweet. I ended up bypassing the automatic transfer relay and opting for a single hardwired, inverter-only AC outlet.

Details and pics of this installation can be found here: http://mellomikeswolfcreekcamper.blogspot.com/2011/10/modification-4-morningstar-suresine-300.html

Shadowcatcher

Re: Morningstar Suresine 300 Installation

What I am doing is very similar with our teardrop trailer and I will be installing a Morningstar inverter and have a Progressive Dynamics converter. My concern is to wire the inverter so that it energizes the AC circuits with out activating the charge function of the converter.

BB.

Re: Morningstar Suresine 300 Installation

The "easiest" method is to get a small automatic transfer switch and connect it so that Shore Power is directed to the balance of your internal AC wiring, and if Shore Power is down, it would switch over to your inverter.

Power Max makes a 30 amp 120 VAC auto transfer switch (with 30 second delay for generator startup/stabilization). I don't know if this is a single or double pole switching device (double pole would be useful if you want to locally ground your TSW inverter's "neutral" lead).

Iota makes several that have been used successfully here. NAWS used to sell them but does not list them now. Search for "Iota Engineering ITS30R".

-Bill

PS: NAWS has a manual transfer switch. And some people make their own transfer switch with a standard double throw relay (NO/NC/Comm).

Shadowcatcher

Re: Morningstar Suresine 300 Installation

I am going to co-opt this a bit as I finally figured out what I am going to be doing and how, with some help from a friend. Rather than go with a relay type transfer switch I will be using a 30A DPDT switch. I spent a Bunch of hours finding one! This will be installed so that shore power comes into the switch and one direction powers the converter and the other feeds from the inverter into the AC breakers. With the center off there is no danger of back feeding. I also decided to do the connections to the inverter using Anderson Power Poles. One question, all of the circuits are wired , nothing is grounded to the frame and all of the appliances that will be used i.e. the TV are all two conductor, no ground. Is there a point in even running the ground? and in reality unless you drive a grounding rod what is the point.

waynefromnscanada

Re: Morningstar Suresine 300 Installation

Well if for no other reason, I'd have the system including all electrical boxes etc grounded as usual to a gnd rod, for help in preventing damage from both static electricity and nearby lightening induced spikes and surges.

Windsun

Re: Morningstar Suresine 300 Installation

BB. wrote: »

Iota makes several that have been used successfully here. NAWS used to sell them but does not list them now. Search for "Iota Engineering ITS30R".

Iota quit making the ITS transfer switches about 18 months ago. They no longer met UL and it apparently was not worth it for them to get them recertified.