Best inverter for the buck

[Bill Roosa]

I'm with Stu, have at it. That is how progress is made
I'm also slightly more pessimistic having seen first hand what floating grounds can do to things. You might want to check your insurance policy to make sure it covers "non-approved solutions in AC wiring" The electrical code exist to ensure safety not to lower the price of things. The insurance companies are very unlikely to approve anthing that is not up to code. they will certainly not be inclined to fulfill a claim due to faulty wiring.

Pete; 120 AC is very dangerous. I do not think I can overestimate the amount of damage your solution is capable of. Total loss of the boat and possible loss of life. You say you consider electrolysis a safety issue also but I'm not thinking you would loose the boat or get somebody killed due to a rusted thru hull or the prop falling off. the rate that these things happen allow for routine inspection to catch them well in time to effect a repair. 120 volt AC does not.

 

[Bill Roosa]

There is no need to rewire the boat AC. Just connect shore power and the inverter hots and neutrals to a transfer switch and make sure the AC panel buss is busted in two to prevent the water heater and battery charge being energized when on inverter power.

 

[Stu Jackson]

Or just turn those two switches off. Not too hard. I mentioned the charger switch issue in my first link in an earlier post.

Pete's also hot on this same trail over at cruisersforum. He's been getting some poor advice on grounding from one guy.

OTOH, mitiempo (Brian) has been telling him the same thing we have. Including a great wiring diagram. http://www.cruisersforum.com/forums/f14/best-inverter-for-the-buck-75078-3.html

Here's another response from someone who didn't use a transfer switch:

Okay, I messed up. The side of the unit has three plugs. From my AC panel I've got hard wired on heavy gauge wire a plug that plugs into the unit. It makes the power get to the AC panel and from there, through the boat. HOWEVER, after a year of being out there I pulled into a dock and had the "opportunity" to plug in to real power. I forgot to unplug the inverter and that's what fried it. Dumb on my part and totally my fault. I "knew better" (we hadn't put in a switch -- recommended above) to insure idiot moments wouldn't happen. THAT is still in my things to do list but I'm way smarter now, you know?

 

[prroots]

Or just turn those two switches off. Not too hard. I mentioned the charger switch issue in my first link in an earlier post.

Pete's also hot on this same trail over at cruisersforum. He's been getting some poor advice on grounding from one guy.

OTOH, mitiempo (Brian) has been telling him the same thing we have. Including a great wiring diagram. http://www.cruisersforum.com/forums/f14/best-inverter-for-the-buck-75078-3.html

Here's another response from someone who didn't use a transfer switch:

Okay, I messed up. The side of the unit has three plugs. From my AC panel I've got hard wired on heavy gauge wire a plug that plugs into the unit. It makes the power get to the AC panel and from there, through the boat. HOWEVER, after a year of being out there I pulled into a dock and had the "opportunity" to plug in to real power. I forgot to unplug the inverter and that's what fried it. Dumb on my part and totally my fault. I "knew better" (we hadn't put in a switch -- recommended above) to insure idiot moments wouldn't happen. THAT is still in my things to do list but I'm way smarter now, you know?

Sounds like you're mixing up things to me. I have consistently supported the idea of a switch of some type to be sure that inverter can never be connected to shore power. Also, the idea of having to remember to turn off stuff is fraught with errors at least on our boat where Murphy's law is alive and well. The good news is that with all the feedback, some of it good and some of it no so, I'm learning a lot and hopefully, will be able to soon share a workable solution that satisfies all my requirements.
Pete

 

[prroots]

Pete,
Please don't try to cut corners on shore/inverter isolation. Sterling sells a VERY REASONABLY priced transfer switch. They do the same as the Newmar or Blue Sea switches only for a lot less money.

Sterling AC Transfer Switch $29.00

Would this smaller one also serve the purpose on our 30 Amp shore connection?

http://sterling-power-usa.com/sterlingpowerusamanualcrossoverswitch-1.aspx

or perhaps the extra current rating is worthwhile for the small difference in price?
Pete

 

[prroots]

I've finally drawn up a crude schematic representing my concept to date. Comments as always welcome.
Pete

 

[Maine Sail]

I've finally drawn up a crude schematic representing my concept to date. Comments as always welcome.
Pete

As a new "source" of power the breaker for the inverter should be double pole and break hot and neutral.

You also need a green protective earth case ground for the inverter no smaller and one wire GA less than the DC wires..

 

[prroots]

So you're giving up a circuit breaker for the boat outlets when on the inverter? Personally I don't feel comfortable relying on the GFI in the inverter as my sole means of circuit protection.

Thanks. There is a 15 Amp circuit breaker shown on the AC output of inverter. In fact, I did check with Samlex and they said it was required ie, don't depend on the overload shutdown.
Pete

 

[Maine Sail]

Thanks. There is a 15 Amp circuit breaker shown on the AC output of inverter. In fact, I did check with Samlex and they said it was required ie, don't depend on the overload shutdown.
Pete

Saw that and edited... See above should be double pole..

 

[prroots]

As a new "source" of power the breaker for the inverter should be double pole and break hot and neutral.

You also need a green protective earth case ground for the inverter no smaller and one wire GA less than the DC wires..

Thanks. OK, I'll make it a double pole breaker and add a earth ground to inverter chassis.
Pete

 

[Stu Jackson]

Inverter wiring & Safety

I've finally drawn up a crude schematic representing my concept to date. Comments as always welcome.
Pete

Pete, as drawn, your "rotary switch" is either on or off. If it's on when you plug into shorepower, and you turn on your inverter, there is the distinct possibility that your inverter will feed back into the shorepower and fry your new inverter. Please look at the wiring diagram Brian provided to you over on the cruisersforum and see how the "either or" switch is wired.

 

[prroots]

Pete, as drawn, your "rotary switch" is either on or off. If it's on when you plug into shorepower, and you turn on your inverter, there is the distinct possibility that your inverter will feed back into the shorepower and fry your new inverter. Please look at the wiring diagram Brian provided to you over on the cruisersforum and see how the "either or" switch is wired.

Thanks. If there's an error it's probably just the way I've drawn it. The actual switch will be in position 1 for shore, 2 for inverter, or off. Position 3 will be unused. Since it's double pole, both line and neutral will be switched. Here is the link to the switch:
http://sterling-power-usa.com/sterlingpowerusamanualcrossoverswitch-1.aspx
and I've also attached a installation sheet that they sent me.
Pete

 

[Gunni]

You know, Beneteau shipped the 411 with a factory option Inverter that powers all the port AC outlets. You could just get the OEM wiring diagram Beneteau and connect the particular galley circuit you want.

 

[Stu Jackson]

Thanks. If there's an error it's probably just the way I've drawn it. The actual switch will be in position 1 for shore, 2 for inverter, or off. Position 3 will be unused. Since it's double pole, both line and neutral will be switched. Here is the link to the switch:
http://sterling-power-usa.com/sterlingpowerusamanualcrossoverswitch-1.aspx
and I've also attached a installation sheet that they sent me.
Pete

When I teach, I provide my students examples of the "parts" they can assemble. That's what Brian's diagram does for you. "...just the way I've drawn it..." means it's not what you intend to install, so, guess it's "back to the drawing board" since, unless you're Maine Sail, you NEED the wiring diagram to do it right when you install it.

I also note that the Sterling model is a 230V unit. While I haven't gone back to the earlier links, is the 230V model the same as the 120V model?

In addition to your "reinventing the wheel" approach, it appears you may not have grasped the basic concept of the "either / or" purpose of the switch.

Good luck.

 

[mitiempo]

There is one letter different in the switch model numbers between the US and UK. The only manual I found online was on the UK site. As long as its rating is ok for the amperage either will work fine.

 

[Stu Jackson]

Yes, I just went back to the link and it says "up to 230V".

 

[prroots]

In addition to your "reinventing the wheel" approach, it appears you may not have grasped the basic concept of the "either / or" purpose of the switch.
Good luck.

Where do these ideas come from? I understand perfectly the purpose of the switch. It seems that you're unhappy because we've come up with a concept that works well despite your negative attitude.
Pete

 

[Stu Jackson]

More inverter wiring

Pete, if you wired it the way you show, it wouldn't work. I fail to realize how attempting to increase your safety, as discussed earlier in this thread, is negative. You asked what it looks like and we answered.

The concept is: two different source IN to the switch, inverter and shorepower, and only one OUT to your loads.

Good luck, again.

 

[Maine Sail]

Where do these ideas come from? I understand perfectly the purpose of the switch. It seems that you're unhappy because we've come up with a concept that works well despite your negative attitude.
Pete

Pete,

What you are proposing "can" work. It would not be a way I'd wire it but so long as both sources can't "bump" each other it can be safe.

The problem is that this can still allow two AC "sources" to be on at the same time, on the same boat, which is generally frowned upon.

If you are doing as you draw, which is a little incomplete but I see where you're going, you don't need to break the neutral of the inverter with a double pole breaker. My earlier post was incorrect as I was thinking of the AC trans switch before the main breaker. If the transfer switch is before the main breaker it needs to break both hot & neutral but yours is after so you only need to break inverter hot.

 

[prroots]

Pete,

What you are proposing "can" work. It would not be a way I'd wire it but so long as both sources can't "bump" each other it can be safe.

The problem is that this can still allow two AC "sources" to be on at the same time, on the same boat, which is generally frowned upon.

If you are doing as you draw, which is a little incomplete but I see where you're going, you don't need to break the neutral of the inverter with a double pole breaker. My earlier post was incorrect as I was thinking of the AC trans switch before the main breaker. If the transfer switch is before the main breaker it needs to break both hot & neutral but yours is after so you only need to break inverter hot.

Thanks. I intentionally switch the circuit downstream of the breaker to the AC outlets. That way I meet my requirement (mentioned earlier) that I can never feed either water heater or battery charger from the inverter. I really do worry about inadvertently leaving them on while running the inverter and this way they can't drain the battery. It also allows everything in that part of the circuit including cable, switch, and breaker to be sized for 15 Amps vs the full 30 Amps. I'll stick with a single pole breaker as you suggest. No sense unnecessarily complicating things.
Pete